# 68 GTO 400 CAN I CHANGE OIL PUMP W ENGINE IN CAR?



## 1968GTOMAN (Aug 3, 2020)

Hi my oil pressure is around 9PSI at idle it goes up to 60PSI when I first start the engine but after driving a few miles to a traffic light it will be 9PSI at idle.
I still hear clicking, ( some may have seen my recent post about engine clicking.)
The mechanics i know seem to go silent when i mention changing the oil pump, tube and screen, just as a maintenance thing, and it would rule that out as far as the cause. "If its like $600, lets do it." I say.
Can i just pull off the oil pan and do it?
Thanks!
Bill


----------



## pontrc (Mar 18, 2020)

Little more than a maintenance thing! Others have tried it but said would not do again. The smart play is to pull the engine, put it on a stand flip it and change it. But what is the oil pressure while driving?


----------



## 1968GTOMAN (Aug 3, 2020)

Thanks, yeah It goes up when throttle is pressed. Never really look down at gauge during driving, i believe it is in the 30s to 40s but not certain.
(The rear end was just rebuilt yesterday and added a posi, and today car is on a dyno to tune for max performance. Running a torquer II single plane manifold and Holley 750 double pumper carburetor.)
Just concerns me, with symptom of low idling oil pressure, revving the car to 5000 or 5500 rpm during the 5 or 6 hour procedure, as ive never taken it above 4500 that ive noticed. The engine has not been rebuilt in over 20 years. Previous owner had the car that long and told me so. No history is known before he owned it.
Thank you!
Bill


----------



## pontrc (Mar 18, 2020)

Bill I would say she is ready for a rebuild, would not risk the Dyno test. You might make it worse and more expensive if a rod lets go


----------



## pontrc (Mar 18, 2020)

That is the weak point in Pontiac engines


----------



## PontiacJim (Dec 29, 2012)

1968GTOMAN said:


> Hi my oil pressure is around 9PSI at idle it goes up to 60PSI when I first start the engine but after driving a few miles to a traffic light it will be 9PSI at idle.
> I still hear clicking, ( some may have seen my recent post about engine clicking.)
> The mechanics i know seem to go silent when i mention changing the oil pump, tube and screen, just as a maintenance thing, and it would rule that out as far as the cause. "If its like $600, lets do it." I say.
> Can i just pull off the oil pan and do it?
> ...


Read my Post #4 from this forum question:









Pan removal


Is it possible to drop the oil pan on a 65 GTO without pulling the engine? I may need a new oil pump?




www.gtoforum.com


----------



## pontrc (Mar 18, 2020)

Now that you understand what Jim was saying fighting gravity is not a good thing. I would pull it and rebuild it


----------



## Lemans guy (Oct 14, 2014)

Your oil pressure seems consistent with your RPM’s why do you think this is low?

what pressure are you expecting with hot/warm oil? Seems normal, rolls up to 60 PSI....30 to 40 when cruising midrange...

say a 9000 RPM idle with 9 PSI....what am I missing here that this is so bad?


----------



## pontrc (Mar 18, 2020)

Agree with the oil pressure LG , but the clicking noise and a 20 year old engine questioning the health of it


----------



## 1968GTOMAN (Aug 3, 2020)

The engine is a 1970 GTO engine, for the record.
Everyone who hears 400 engine believes it has a cam upgrade, but no idea what it is or if its ever been rebuilt.


----------



## 1968GTOMAN (Aug 3, 2020)

Lemans guy said:


> Your oil pressure seems consistent with your RPM’s why do you think this is low?
> 
> what pressure are you expecting with hot/warm oil? Seems normal, rolls up to 60 PSI....30 to 40 when cruising midrange...
> 
> say a 9000 RPM idle with 9 PSI....what am I missing here that this is so bad?


The consensus of people ive shoken to in the area here belueve that the idle oil pressure should be 21psi or higher.


----------



## 1968GTOMAN (Aug 3, 2020)

Well they did the dyno tune, said it has much more power. Hes only revealing to me that it started with only 173 HP. Hes going to have me drive it and then he's going to reveal how high he raised the HP.
He said the motor is WORN OUT. Says he doesnt think its ever been rebuilt.
Says if i dont dog it i can probably be fine til winter when we rebuild.
Said there was a bunch of blow by during the dyno all sprayed oil, he thought my antifreeze hose broke but it was just oil spraying out of the breather. Said tings are shot.
Im going to have him rebuild it. He knows what he's doing.


----------



## 1968GTOMAN (Aug 3, 2020)

Rings shot i meant


----------



## Old Man Taylor (May 9, 2011)

1968GTOMAN said:


> The consensus of people ive shoken to in the area here belueve that the idle oil pressure should be 21psi or higher.


I agree it would be nice for the pressure to be higher, but you're not hurting anything running it like that. When mine got that low on one of my engines it was due to a funny wear pattern on the cam bearing, giving the oil a direct path the pan. It still ran fine.


----------



## 1968GTOMAN (Aug 3, 2020)

Old Man Taylor said:


> I agree it would be nice for the pressure to be higher, but you're not hurting anything running it like that. When mine got that low on one of my engines it was due to a funny wear pattern on the cam bearing, giving the oil a direct path the pan. It still ran fine.


Huh! No kidding?? Huh.. 
That would be a positive thing, i hope my story resembles yours. It survived the 5500 rpm dyno, so yeah huh...


----------



## Mine'sa66 (Oct 30, 2019)

If it survived a dyno run, it's getting oil pressure when it needs to.
9 psi is low at idle, but there are simple causes as well as serious ones. 
Seems like a moot point as you're planning a rebuild very soon anyway.
One of my old timer technicians used to tell folks who stressed over the dip in pressure at idle..."in reality, any is enough" A bit of an overstatement, but basically true.


----------



## 1968GTOMAN (Aug 3, 2020)

Mine'sa66 said:


> If it survived a dyno run, it's getting oil pressure when it needs to.
> 9 psi is low at idle, but there are simple causes as well as serious ones.
> Seems like a moot point as you're planning a rebuild very soon anyway.
> One of my old timer technicians used to tell folks who stressed over the dip in pressure at idle..."in reality, any is enough" A bit of an overstatement, but basically true.


Lol yeah, i looked in the breather and inside under the oil fill cap a few months ago when i first got the car and it was wet in there.


----------



## Lemans guy (Oct 14, 2014)

Yes, pontrc I agree the clicking noise and engine age are issues. Just did not see that oil pressure alone as a cause of concern. It also matters what viscosity oil is in there.

But line minesa66 said idle pressure can be low... as long as it is not so low. GTOman’s looks like he had it at idle to match RPM speed, and up to 60 and 30 or 40 At cruise, seemed ok not out of line to me me,...are we really expecting much higher pressures?


----------



## 1968GTOMAN (Aug 3, 2020)

Lemans guy said:


> Yes, pontrc I agree the clicking noise and engine age are issues. Just did not see that oil pressure alone as a cause of concern. It also matters what viscosity oil is in there.
> 
> But line minesa66 said idle pressure can be low... as long as it is not so low. GTOman’s looks like he had it at idle to match RPM speed, and up to 60 and 30 or 40 At cruise, seemed ok not out of line to me me,...are we really expecting much higher pressures?


I was just being told by local people it should be in the 20s at idle. 
Seemed very low at 9psi, not much farther to drop lol


----------



## 1968GTOMAN (Aug 3, 2020)

This is my dyno report. Im not sure which is the actual HP. I'm sure you guys know how to interpret.


----------



## Mine'sa66 (Oct 30, 2019)

1968GTOMAN said:


> This is my dyno report. Im not sure which is the actual HP. I'm sure you guys know how to interpret.


258.58 HP


----------



## PontiacJim (Dec 29, 2012)

Mine'sa66 said:


> 258.58 HP



I am assuming that is rear wheel HP not flywheel HP seeing the engine is still in the car? Or was it converted to flywheel HP? Not sure myself. If flywheel HP, very low for a 1970 GTO engine with the new intake, carb, & headers, so assume rear wheel HP. Using a quick online calculator and 258 rear wheel HP, I got 323 HP at the flywheel (and it may actually be lower), which is still way low for that engine.

So if that is correct, yep, maybe that 20 year old engine is well overdue for an overhaul.


----------



## 1968GTOMAN (Aug 3, 2020)

Mine'sa66 said:


> 258.58 HP


Thanks, Not very good huh?
I thought as i was leaving yesterday he told me in the 260s, maybe not..
He said its because the engine is "WORN OUT"
Said with a rebuild I could possibly expect an extra 100,hp
Theres blow by happening when stomping on gas.
Although the oil stays clean, not getting black like if it was burning.
Said with a rebuild I could possibly expect an extra 100,hp


----------



## pontrc (Mar 18, 2020)

Not bad as you think remember that is rear wheel horsepower


----------



## 1968GTOMAN (Aug 3, 2020)

pontrc said:


> Not bad as you think remember that is rear wheel horsepower


Yes it is rear wheel, he just texted me back


----------



## 1968GTOMAN (Aug 3, 2020)

PontiacJim said:


> I am assuming that is rear wheel HP not flywheel HP seeing the engine is still in the car? Or was it converted to flywheel HP? Not sure myself. If flywheel HP, very low for a 1970 GTO engine with the new intake, carb, & headers, so assume rear wheel HP. Using a quick online calculator and 258 rear wheel HP, I got 323 HP at the flywheel (and it may actually be lower), which is still way low for that engine.
> 
> So if that is correct, yep, maybe that 20 year old engine is well overdue for an overhaul.


Yes he just texted back, said its rear wheel, said HP and said to add 28% to get flywheel which he says is 330.
As far as 20 years, thats just how long the previous owner had the car, my mechanic said yesterday that he thinks this thing has never been rebuilt. He basically thinks its a museum piece from 1970.


----------



## 1968GTOMAN (Aug 3, 2020)

One thing i can report, there is some good power. 
When its warmed up,like at a gas pump, starts up with a pop, as soon as i turn key, starter doesn't even barely need to turn. 
The gas peddle isnt sensative, like a new car, but when you push an inch or two down it takes off.
The mechanic did a maybe 60 to 70 ft burnout in front of his shop, i wasnt there but i saw the long skid marks from the new posi rear he just rebuilt (and added the posi) for me. I even got the chrome cover, looks cool.
If your going to completely rebuild the rear, you might as well cap it with a pretty chrome cover.


----------



## Mine'sa66 (Oct 30, 2019)

PontiacJim said:


> I am assuming that is rear wheel HP not flywheel HP seeing the engine is still in the car? Or was it converted to flywheel HP? Not sure myself. If flywheel HP, very low for a 1970 GTO engine with the new intake, carb, & headers, so assume rear wheel HP. Using a quick online calculator and 258 rear wheel HP, I got 323 HP at the flywheel (and it may actually be lower), which is still way low for that engine.
> 
> So if that is correct, yep, maybe that 20 year old engine is well overdue for an overhaul.


That is to the wheels (from the dyno shown in the picture). As a general rule, if your drivetrain is working "normally" that's probably 300-325 at the crank.

EDIT;
I responded from my alerts...didn't see the extra posts. I ballparked 325 off the top of my head. Good to know my ballpark agrees with the calculator lol


----------



## 1968GTOMAN (Aug 3, 2020)

Well thank you!!
I appreciate your insight!


----------



## Mine'sa66 (Oct 30, 2019)

1968GTOMAN said:


> Well thank you!!
> I appreciate your insight!


When you have it done, are you planning to upgrade a lot of stuff or just freshen it?
If you're upgrading, save the old stuff. If it's truly a survivor there may be desirable original parts.
Also, remember a dyno measurement at the wheel tells you what your bottom line actually is. Whatever calculator out there is doing is taking inputs and doing some math. It's assuming everything's working together and correctly in your drive train.
You could have 500hp at the crank and get 250hp at the wheel if you have drivetrain issues.
Not saying you do, just putting that out there for the benefit of other readers.
From the sounds of how the car runs and drives, it sounds like yours is fine. 300-350 hp at the crank is normal stock stuff and the way you describe how it goes sounds like you're getting >250 at the wheel.


----------



## Jetzster (Jan 18, 2020)

PontiacJim said:


> So if that is correct, yep, maybe that 20 year old engine is well overdue for an overhaul.





1968GTOMAN said:


> Hi my oil pressure is around 9PSI at idle it goes up to 60PSI when I first start the engine but after driving a few miles to a traffic light it will be 9PSI at idle.
> I still hear clicking,


Bill , like PJ & (also Picard on Star Trek) has said:
“Make it So”😄lol


----------



## 1968GTOMAN (Aug 3, 2020)

Jetzster said:


> Bill , like PJ & (also Picard on Star Trek) has said:
> “Make it So”😄lol


I dont get it.??
Im sure its funny, but i never watched the picard star trek only watched James T Kirk version.


----------



## 1968GTOMAN (Aug 3, 2020)

One thing that sucks is the bad fumes coming into the cab. The exhaust has no visible smoke but i get like a rich exhaust gas fume smell, my clothes get covered with it, my nose burns. 
The mechanic said he noticed that but nothing can be done because the rings are shot and everything is leaking through the engine, and also he said its coming out of the breather. 
That really to me doesnt sound quite 100% accurate because the carb that was on the car when first purchased and delivered to me was an Edelbrock 750 and there wasnt much great power but there wasnt the fumes.
It just seems like its burning rich.
He is an expert at carburetors, rebuilding, tuning, he we wouldnt just lie to make me go away.
I don't know but its bad trying to enjoy the ride with getting that in my lungs.


----------



## Jetzster (Jan 18, 2020)

See Post below


----------



## Jetzster (Jan 18, 2020)

1968GTOMAN said:


> One thing that sucks is the bad fumes coming into the cab. The exhaust has no visible smoke but i get like a rich exhaust gas fume smell, my clothes get covered with it, my nose burns.
> The mechanic said he noticed that but nothing can be done because the rings are shot and everything is leaking through the engine, and also he said its coming out of the breather.
> That really to me doesnt sound quite 100% accurate because the carb that was on the car when first purchased and delivered to me was an Edelbrock 750 and there wasnt much great power but there wasnt the fumes.
> It just seems like its burning rich.
> ...


Bill
With the oil splash issues , vapors , lifter/exhaust clicks, and numerous loose tolerances affecting the Oil pressure So much when it’s cold vs hot , just seems like the best idea is bite the bullet and get engine a full rebuild,
You’re gonna keep this car along time so might as well have the engine taken completely out, do more homework and Find a shop With a great reputation that actually knows Pontiacs
Get it redone ,with a warranty ,and a ‘fixed’price ,like PJ sez, everything from the block Oil pan to the air cleaner, keeping as much original on it as possible. It sounds like
There’s too many things to chase here if you dont Have a solid foundation to start with
‘Make it so’ is just us saying ‘get it rebuilt’, you been
Through enuf of engine and mechanic
Stress and need a fresh start here..
Hey,Winters coming, take it in ,drop it off for the duration , put yer feet up and focus on other things for awhile, it could be all done by early Spring just the right time for you to get the call to come in ,fire up, drive and enjoy this cool car properly and be able to breathe good air and feel it’s true power
(You’ll know what chu really got then.)
FYI also I liked Kirk better too)
And if anything with that engine by chance still ain’t right, it’s on their head not yours,
but it will be fine man very fine


----------



## 1968GTOMAN (Aug 3, 2020)

Jetzster said:


> Bill
> With the oil splash issues , vapors , lifter/exhaust clicks, and numerous loose tolerances affecting the Oil pressure So much when it’s cold vs hot , just seems like the best idea is bite the bullet and get engine a full rebuild,
> You’re gonna keep this car along time so might as well have the engine taken completely out, do more homework and Find a shop With a great reputation that actually knows Pontiacs
> Get it redone ,with a warranty ,and a ‘fixed’price ,like PJ sez, everything from the block Oil pan to the air cleaner, keeping as much original on it as possible. It sounds like
> ...


I cant disagree with you. The mechanic who did the dyno rebuilds engines regularly so Im just going to have him do it. We have already talked about me bringing the car back there in December and he said it will take about 6 weeks.
The thing is. The exhaust fumes that smell like improper combustion, like its running too rich, i think that must be adjustable at the carb, he says gas and oil are leaking through past the rings ending up in the exhaust.
Theres no smoke from tail pipes, there's no residue collecting on the rear bumper indicating poor combustion. The oil stays clean, doesnt turn black. The carb i had on before , it didnt make this horrible smell ..Dont you think that i should try to make it burn leaner by adjusting something? 
Thanks,
Bill


----------



## 1968GTOMAN (Aug 3, 2020)

It is a beautiful creation. One of the most iconic cars on the planet


----------



## O52 (Jan 27, 2019)

Personally I'd find another shop. You seem to have a lot of doubt in your mind regarding their answers to your concerns. And the fact that "he builds a lot of engines" doesn't build a lot of confidence in my mind either. 

There hasn't been a Pontiac engine built since 79 and most engine shops never see one. 
Once you've been in the Pontiac hobby for a while you'll know that rebuilding a Pontiac engine has a lot of nuances that need to be addressed that other engines don't have. And only a few old time mechanics know what they are. 

I would get references from other Pontiac owners that this shop has rebuilt engines for before moving forward. I would also buy Rocky Rotella's book on how to rebuild a Pontiac V-8. He describes the rebuilding process in great detail including those little Pontiac 'Nuances' that will make or break a successful rebuild.


----------



## 1968GTOMAN (Aug 3, 2020)

I hear ya, thing is , he does build pontiac engines. Theres a shop that he builds all their engines for them. And in winter he gets booked up with engine builds.
I just texted him about the fuel combustion fumes, he said could be an exhaust leak somewhere for it to be coming up into the car. As mentioned there's no residue on the tailpipes or the back bumper, rear of car, of any faulty combustion. It just smells bad.
He said meanwhile to try 87 octane.
I am surprised that that could make any difference.
Im willing to try that for sure. I'll go do that now.


----------



## Mine'sa66 (Oct 30, 2019)

1968GTOMAN said:


> I hear ya, thing is , he does build pontiac engines. Theres a shop that he builds all their engines for them. And in winter he gets booked up with engine builds.
> I just texted him about the fuel combustion fumes, he said could be an exhaust leak somewhere for it to be coming up into the car. As mentioned there's no residue on the tailpipes or the back bumper, rear of car, of any faulty combustion. It just smells bad.
> He said meanwhile to try 87 octane.
> I am surprised that that could make any difference.
> Im willing to try that for sure. I'll go do that now.


It sounds like he installs Pontiac engines, not builds them? Which might be good. If you didn't get these fumes before, then something's changed. I recall you had someone (them?) fix a header leak? Perhaps it's leaking. Sounds though, like the change that resulted in the fumes was the carb. You don't just bolt on a carb and have it dialed in out of the box very often if really ever. 
I don't get try 87 octane. That's the lowest octane you get from a pump. Can't see the upside of that.
If it's running rich, you'll smell it standing behind the car. If it's getting inside the car, most likely it's coming from a leak in the exhaust system up front, or a body leak in the trunk drawing in the exiting exhaust.


----------



## 1968GTOMAN (Aug 3, 2020)

Mine'sa66 said:


> It sounds like he installs Pontiac engines, not builds them? Which might be good. If you didn't get these fumes before, then something's changed. I recall you had someone (them?) fix a header leak? Perhaps it's leaking. Sounds though, like the change that resulted in the fumes was the carb. You don't just bolt on a carb and have it dialed in out of the box very often if really ever.
> I don't get try 87 octane. That's the lowest octane you get from a pump. Can't see the upside of that.
> If it's running rich, you'll smell it standing behind the car. If it's getting inside the car, most likely it's coming from a leak in the exhaust system up front, or a body leak in the trunk drawing in the exiting exhaust.


Thank you yes, i should check the trunk! Good idea, but its newish seals one the trunk.
Somebody told me that since older engines werent designed to run on high octane, low octane is goung to burn like its designed.
Never thought lower octane could be better, but who knows, worth a try. I feel like im getting gassed to death when i stop at a red light


----------



## pontrc (Mar 18, 2020)

X2 with Mine it’s a mixture adjustment in the carb. Do not try the 87 these engines love the good stuff 91 and higher


----------



## Old Man Taylor (May 9, 2011)

DO NOT try 87 Octane. That suggestion is nonsensical unless he is trying to get you to blow it up.


----------



## Lemans guy (Oct 14, 2014)

Exactly agree, Octane is a chemical that does one thing only.....resists knocking from compression.....that is all....it does not give you more power, it does not make you go faster....and it is needed in these higher compression engine so that the knock is reduced or eliminated altogether....

cannot see any benefit to using 87 octane in a 66 Pontiac engine unless you want to destroy it....

you have an exhaust leak like the guys said, I have had em just like that, usually from a stick closed heat riser valve....

but somewhere near the header manifold connection it is pouring out and into the car through the firewall wire holes and vac line holes etc...

ask your shop if he has a smoke machine and ask him to smoke the exhaust, the smoke will come out the leak under the hood..he will plug the tail pipes with rubber plugs, if he does not call another shop, or even a muffler shop, ...those guys can spot the exhaust leaks easy they see so many

it does not have to be a hot rod shop to find an exhaust leak...


----------



## Mine'sa66 (Oct 30, 2019)

1968GTOMAN said:


> Thank you yes, i should check the trunk! Good idea, but its newish seals one the trunk.
> Somebody told me that since older engines werent designed to run on high octane, low octane is goung to burn like its designed.
> Never thought lower octane could be better, but who knows, worth a try. I feel like im getting gassed to death when i stop at a red light


I suggest not taking too much advice from the chap that said older engines weren't designed to run on high octane fuel.
The exact opposite is true.
Octane is very misunderstood. Basically, octane is a measurement of how volatile(flammable) fuel is. Higher octane gasoline is less volatile than low octane fuel. That's why you can compress it further before it self ignites.
That's also why there is no benefit from running higher octane fuel in a vehicle that does not require it. If your engine does not detonate 87 octane fuel, then running anything higher is doing you absolutely no good.


----------



## 1968GTOMAN (Aug 3, 2020)

Lemans guy said:


> Exactly agree, Octane is a chemical that does one thing only.....resists knocking from compression.....that is all....it does not give you more power, it does not make you go faster....and it is needed in these higher compression engine so that the knock is reduced or eliminated altogether....
> 
> cannot see any benefit to using 87 octane in a 66 Pontiac engine unless you want to destroy it....
> 
> ...


Ah! Thats a good idea! A smoke machine, im going to ask about that ,thanks!
I drove tonight with windows up and didnt sense the smell, then opened the window and start to get it again. 
Behind and anywhere near that car it STINKS!!
Just bad pollution machine.
Im sure the carb isnt adjusted properly for the smell, but the mechanic who did the dyno tune said he adjusted it for max power, not for smell. Said ill lose power if we tweak it for cleaner air smell and then said " The dyno dont lie." Said i could turn the bleeders out a turn to see if that helps.
He said the air to fuel ratio is 12.8. Said thats perfect.
Ill try to follow his guidance to turn the bleeders out a turn but i need to look that up to see where that is on the holley 750 mechanical secondary carb.
I dont think he means the four point adjustment screws. Hmm


----------



## 1968GTOMAN (Aug 3, 2020)

One thing for sure though. The car runs REALLY good! Its a joy to drive, like a carnival ride.


----------



## Mine'sa66 (Oct 30, 2019)

1968GTOMAN said:


> Ah! Thats a good idea! A smoke machine, im going to ask about that ,thanks!
> I drove tonight with windows up and didnt sense the smell, then opened the window and start to get it again.
> Behind and anywhere near that car it STINKS!!
> Just bad pollution machine.
> ...


14.7-1 is stoichiometric ratio for gasoline. That's the most efficient, thourough burn ratio. Doesn't mean it's the most power though. I can't smell it, but I would assume it's very rich, 12.8-1 would be very rich. Turning the mixture screws out is going to richen it more. I would turn them a half turn in. You don't want to blindly adjust this, but I'd say it's safe to move one half turn. If you lose 10HP at 5k rpm, you aren't going to notice and if it cleans it up, you're going to enjoy the ride a whole lot more.


----------



## 1968GTOMAN (Aug 3, 2020)

He just responded to my text, he said 13.0 is lean line, 10.0 is rich. Says im 12.8.
You say turn the screws in, which makes more sense to make it more lean. I would do that. Maybe he mispoke about loosening screw by mistake. He is very helpful and responsive. That means a great deal to have him and you all interested in my $35k cost car (right now but going up and up.)
I enjoy the subject as well as need the guidance.
Thanks!!


----------



## 1968GTOMAN (Aug 3, 2020)

Mine'sa66 said:


> I suggest not taking too much advice from the chap that said older engines weren't designed to run on high octane fuel.
> The exact opposite is true.
> Octane is very misunderstood. Basically, octane is a measurement of how volatile(flammable) fuel is. Higher octane gasoline is less volatile than low octane fuel. That's why you can compress it further before it self ignites.
> That's also why there is no benefit from running higher octane fuel in a vehicle that does not require it. If your engine does not detonate 87 octane fuel, then running anything higher is doing you absolutely no good.


This is thouroughly interesting!
Thank you for that summation.


----------



## 1968GTOMAN (Aug 3, 2020)

T


Mine'sa66 said:


> I suggest not taking too much advice from the chap that said older engines weren't designed to run on high octane fuel.
> The exact opposite is true.
> Octane is very misunderstood. Basically, octane is a measurement of how volatile(flammable) fuel is. Higher octane gasoline is less volatile than low octane fuel. That's why you can compress it further before it self ignites.
> That's also why there is no benefit from running higher octane fuel in a vehicle that does not require it. If your engine does not detonate 87 octane fuel, then running anything higher is doing you absolutely no good.


Thats not my mechanic who did the dyno that said that, its a different friend who built a 70ish camaro.
What he was saying is he was trying to find agreement with my mechanic who said "Try 87."
My friend was saying "That kinda makes sense because cars were able to run on lower octane fuel in those days so maybe the higher octane fuel isnt burning the way the 70 pontiac motor was designed.."
So i guess he was sort of right pontificating on the suggestion to try 87 octane.


----------



## Old Man Taylor (May 9, 2011)

All of those guys have it backwards. Up through '70 most cars required about 95 Octane by the new measures. The old way they advertised fuel required 100 Octane.


----------



## Lemans guy (Oct 14, 2014)

12.8 is too rich for any street car. Modern computerized fuel injection runs 14.7 stoich on a very efficient engine with multiple sensors that adjusts the Air Fuel Mixture (AFR) by the millisecond.......our cares will not so that.

I run 13.8 AFR at idle 13.2 or 3 at light throttle cruise,......12.2 for power, accelerator pump shot, or power valve on or secondaries open.....

I see a lot of guys run their cars way too rich, why? It makes it easy to start and feels powerful and they think it is good. But you get the smell of burning fuel you are washing down your cylinder walls with gasoline and you are wasting gas,...

Look 13.8 is still the rich side of 14.7 Stoiciometric, it is not “Lean” running, and if you try to run carbs at 14.7 you will often be up in the 15s or 16s, lean makes you run hot and heat causes detonation and detonation causes heat.....

Now racers are different, Mr Taylor could add much here, and their mixture have to be set for the race and max power.....so they may run richer, because they don’t plan on idling much or cruising at light throttle, they want power all the time and power needs a richer mixture.

Minesa66 advice is spot on lean it a bit.....also remember that the mixture screws are not “mixing” anything,....they are providing a mixture of fuel and air, determined by the idle air bleeds and high speed air bleeds and carb passages,....when you turn the mixture screws you get more “fuel and air mixture” or less “fuel and air mixture”...

Back to octane, the “octane number” is a measurement,...after the hydrocarbon “Octane Is added to the gasoline mixture. Octane is obtain at the refinery’s catalytic cracker, those big towers at the refinery that breaks down the Crude oil.....It is as minsa66 said added to resist the ability of the gas to detonate from compression alone.....it does not give you more power.


----------



## 1968GTOMAN (Aug 3, 2020)

Lemans guy said:


> 12.8 is too rich for any street car. Modern computerized fuel injection runs 14.7 stoich on a very efficient engine with multiple sensors that adjusts the Air Fuel Mixture (AFR) by the millisecond.......our cares will not so that.
> 
> I run 13.8 AFR at idle 13.2 or 3 at light throttle cruise,......12.2 for power, accelerator pump shot, or power valve on or secondaries open.....
> 
> ...


This is great info!
So to be certain, turn the screws "IN" a half turn, correct? That will make more lean, correct?
Thank you for your valuable time!!


----------



## O52 (Jan 27, 2019)

Theres a great Pontiac shop in Baltimore Maryland. 






Gaydosh Performance - John Gaydosh, Jr. NHRA Driver


Gaydosh Performance competes in the NHRA Mellow Yellow series in the Pro-Stock category.




gaydoshperformance.com


----------



## Mine'sa66 (Oct 30, 2019)

1968GTOMAN said:


> This is great info!
> So to be certain, turn the screws "IN" a half turn, correct? That will make more lean, correct?
> Thank you for your valuable time!!


In to lean, out to richen.


----------



## 1968GTOMAN (Aug 3, 2020)

Thank you have kind of always known that but since I spent all this money on the dyno tune I just wanted to not screw it up


----------



## Jared (Apr 19, 2013)

You may want to do a little more digging on what engine is actually in your car before you spend a ton of money rebuilding it. I know the previous owner said it was a 400 out of a 70 GTO, but if it was a 400 out of a LeMans or one of the big cars from 1970, it would have only had 330 hp when new. Something to consider and try and find out. When your selling a car, "engine out of a GTO" sounds way better than "engine out of a Catalina" if you know what I'm saying. 

That all being said, based on your descriptions, your engine does sound tired, but it may not be as tired as you think it is.


----------



## pontrc (Mar 18, 2020)

I agree Bill to look into a shop who is familiar with Pontiac as O52 suggests to handle and setup the engine to the way you want. You already dug deep pockets out of these shops


----------



## 1968GTOMAN (Aug 3, 2020)

Jared said:


> You may want to do a little more digging on what engine is actually in your car before you spend a ton of money rebuilding it. I know the previous owner said it was a 400 out of a 70 GTO, but if it was a 400 out of a LeMans or one of the big cars from 1970, it would have only had 330 hp when new. Something to consider and try and find out. When your selling a car, "engine out of a GTO" sounds way better than "engine out of a Catalina" if you know what I'm saying.
> 
> That all being said, based on your descriptions, your engine does sound tired, but it may not be as tired as you think it is.


Hi, the numbers actually are confirming a 1970 GTO engine, the heads may not be original though.
But yeah, it really is from a 1970 GTO which leads me to speculate the circumstances. I think its unusual that a 1970 replacement GTO engine would find its way into a 68.
I'm fantasizing that the engine blew under warranty in 1970 and was factory replaced, but I dont know how I could prove that.
Bill


----------



## Greg Hill (Jul 15, 2020)

Are the motor out and fix it if you want to keep it.


----------



## lust4speed (Jul 5, 2019)

There's a reason why those little screws are called "idle adjustment screws". They are not players once the throttle is pressed and the engine RPM climbs. Turning screws has absolutely no effect on cruise or full throttle fuel ratios. The quoted 12.8 is what the mixture was during during the dyno run through the power range and right where it should have been. Hold the engine steady at 3,000 RPM on the dyno and close the idle screws shut -- the AFR meter on a 5,000 RPM power pull is still going to show that 12.8 ratio. Engine won't idle with the screws shut, but it won't care with the throttle wide open. Most standard carbs have three circuits that overlap - idle, transition, and power. Carb starts off at idle on the idle circuit (who'd a guessed), and then goes to a combination of idle/transition circuits and so on until nothing but the power circuit is active. Steady light cruise ratio is ideal at 14.7:1 but that lean will burn valves if it stays that lean during full throttle power pulls. A carburetor is a complicated mass of parts created to provide the needed fuel ratio during all phases of operation.

Just to confuse things more, if you smell raw gas at the tailpipe, then idle is too rich, if you smell rotten eggs the mixture is probably too lean. If the carb seems to be too rich, it might not be adjustment screws but a sticking needle valve not allowing the float to fully close off the fuel allowing fuel level to creep up and add extra gas while idling. With the engine idling and air cleaner off, take a look down into the carb and see if you can spot any gas droplets coming off the doglegs/venturies inside the bore. There should not be any dripping.

Agree with Jim on the 323 HP at flywheel. Usually figure a 20% driveline loss for automatics and that simply comes out to 258.58/.80=323.23 horsepower. In 1970 the factory was still rating engines at 60° ambient temperature, no power accessories and no air cleaner or exhaust, and the current 323 at the flywheel is very respectable.


----------



## CptTheAlex (Jul 17, 2015)

If it helps at all. I have a 1970 Pontiac 400. It was built by Beals racing in thomasville, Nc. Bore .030, forged internals, crank turned over, etc... the whole 9 yards and ran cast iron small valve heads for nearly 5000 miles, running a Dakota digital gauge cluster, I typically saw 45-60 psi driving, and 20 at idle. I have a TH350 trans 3.36 posi rear. Then one day, all of a sudden April 2019, I started seeing warm idle oil psi dropping to 7-10 psi. Scared the hell out of me, at that time my oil pressure sensor was located next to the header off the oil filter housing. Since then, my cruise psi once warm is around 30, shooting to 45-50 if I’m really standing on it. Once I hit a light, my rpms are around 640-650 fairly steady, and the psi sits at 7. At 5000 miles I went to dougs headers, RPM performer intake, and Kaufmann cylinder heads and relocated the OPS next to the dizzy. The engine now has 5600 miles on it, still seeing consistency with those psi numbers. When I spoke to Kaufmann racing, he said that they have seen or heard of those numbers before, sometimes it’s the quality of oil. I run and have always used the Driven 10w-40 oil with ZDDP as I have a flat tappet, nearly bone stock cam. I have yet to hook up a mechanical gauge to verify psi, but I can say that when I swapped out the heads and intake, I inspected the cam, and it looked in great shape. This is my first pontiac and classic, so that low psi scares the shit out of me, but, I figure that if I wasn’t getting oil somewhere, it would’ve exploded by now. Not the way I like to do things, but I’m unsure of what to do, opposed to ripping out the engine and doing it all over again.
Just my experience so far, that I thought I would share with you.


----------



## PontiacJim (Dec 29, 2012)

1968GTOMAN said:


> Hi, the numbers actually are confirming a 1970 GTO engine, the heads may not be original though.
> But yeah, it really is from a 1970 GTO which leads me to speculate the circumstances. I think its unusual that a 1970 replacement GTO engine would find its way into a 68.
> I'm fantasizing that the engine blew under warranty in 1970 and was factory replaced, but I dont know how I could prove that.
> Bill


If the engine was replaced, it would not have a 2-letter code UNLESS is was a replacement for a 1970 GTO and was restamped for such. If the block has a row of numbers above or near the 2-letter code, that would be the Engine Unit Number - making it a production engine installed in a car. The true way to see if it was a replacement block is that it will be stamped with a number preceded by the letters "SR" for Service Block - I think in the same place along the lower side of the water pump/timing cover just at the same place you will find the serial number of the car it originally was installed in.

It is not uncommon to buy a GTO without its original engine as many were blown up through heavy use as they passed one owner to the other. A replacement engine was cheaper to purchase than rebuild the original - and by replacement, it was typically a junkyard engine from a full size car and not another replacement GTO engine.

The 2-digit number in the middle exhaust port will ID the heads. They may or may not be original to the GTO, or could even be original to the car with only a short block swapped in. Until you start date coding your parts using the factory cast date codes, you won't know exactly what you have.


----------



## 1968GTOMAN (Aug 3, 2020)

Thank you for this indepth insight!
I will certainly look for droplets in the carb to see. Very interesting!
What i did was turn the 4 point adjustment screws 1/2 turn inward. That actually pretty much cleared up the fumes but it affected the idle. It was dropping so low i had to turn the idle screw to bring it up. Then i drove a bit and then set the 4 point adjustment screws back outwards 1/4 turn to see if it would be still clean. Well, some fumes have come back but not near as bad.
So essentially i have simply turned all 4 screws in 1/4 turn total.
Strangely though, now im getting a bit of white gas smoke at start up, even though it was warmed up. But driving a very short distance at low speed it clears up and is gone.
The thing is, its running and sounding really good now. Almost feels like that quarter turn made the engine sound a bit better when driving? Is that possible? Maybe just my imagination, but it really rumbles.
Ive really benefitted and learned alot here from you guys, very smart!


----------



## 1968GTOMAN (Aug 3, 2020)

CptTheAlex said:


> If it helps at all. I have a 1970 Pontiac 400. It was built by Beals racing in thomasville, Nc. Bore .030, forged internals, crank turned over, etc... the whole 9 yards and ran cast iron small valve heads for nearly 5000 miles, running a Dakota digital gauge cluster, I typically saw 45-60 psi driving, and 20 at idle. I have a TH350 trans 3.36 posi rear. Then one day, all of a sudden April 2019, I started seeing warm idle oil psi dropping to 7-10 psi. Scared the hell out of me, at that time my oil pressure sensor was located next to the header off the oil filter housing. Since then, my cruise psi once warm is around 30, shooting to 45-50 if I’m really standing on it. Once I hit a light, my rpms are around 640-650 fairly steady, and the psi sits at 7. At 5000 miles I went to dougs headers, RPM performer intake, and Kaufmann cylinder heads and relocated the OPS next to the dizzy. The engine now has 5600 miles on it, still seeing consistency with those psi numbers. When I spoke to Kaufmann racing, he said that they have seen or heard of those numbers before, sometimes it’s the quality of oil. I run and have always used the Driven 10w-40 oil with ZDDP as I have a flat tappet, nearly bone stock cam. I have yet to hook up a mechanical gauge to verify psi, but I can say that when I swapped out the heads and intake, I inspected the cam, and it looked in great shape. This is my first pontiac and classic, so that low psi scares the shit out of me, but, I figure that if I wasn’t getting oil somewhere, it would’ve exploded by now. Not the way I like to do things, but I’m unsure of what to do, opposed to ripping out the engine and doing it all over again.
> Just my experience so far, that I thought I would share with you.


A gentleman on this thread said that if at least its consistent, 9psi at idle, but 50 to 60psi at speed then " Why worry?"
Gave me some sleep after hearing that.


----------



## PontiacJim (Dec 29, 2012)

CptTheAlex said:


> If it helps at all. I have a 1970 Pontiac 400. It was built by Beals racing in thomasville, Nc. Bore .030, forged internals, crank turned over, etc... the whole 9 yards and ran cast iron small valve heads for nearly 5000 miles, running a Dakota digital gauge cluster, I typically saw 45-60 psi driving, and 20 at idle. I have a TH350 trans 3.36 posi rear. Then one day, all of a sudden April 2019, I started seeing warm idle oil psi dropping to 7-10 psi. Scared the hell out of me, at that time my oil pressure sensor was located next to the header off the oil filter housing. Since then, my cruise psi once warm is around 30, shooting to 45-50 if I’m really standing on it. Once I hit a light, my rpms are around 640-650 fairly steady, and the psi sits at 7. At 5000 miles I went to dougs headers, RPM performer intake, and Kaufmann cylinder heads and relocated the OPS next to the dizzy. The engine now has 5600 miles on it, still seeing consistency with those psi numbers. When I spoke to Kaufmann racing, he said that they have seen or heard of those numbers before, sometimes it’s the quality of oil. I run and have always used the Driven 10w-40 oil with ZDDP as I have a flat tappet, nearly bone stock cam. I have yet to hook up a mechanical gauge to verify psi, but I can say that when I swapped out the heads and intake, I inspected the cam, and it looked in great shape. This is my first pontiac and classic, so that low psi scares the shit out of me, but, I figure that if I wasn’t getting oil somewhere, it would’ve exploded by now. Not the way I like to do things, but I’m unsure of what to do, opposed to ripping out the engine and doing it all over again.
> Just my experience so far, that I thought I would share with you.


Thanks for the input and adding to the post. If you want, you can post a new topic on your engine and many here can help walk you through a few checks before having to pull the engine. But, I will throw a few things at you here. 

As you noted, first verify with a mechanical gauge as the gauge, or even sending unit, can go bad. Sometimes it can be a ground issue when you install the sending unit - never put any sealer/sealant on it or it may not make that good ground. It uses a pipe thread that is self sealing as you tighten it up, but do not over tighten, especailly if you put it back at the filter or it will crack the fitting hole and you will need a new filter adapter.

Possibly a ground issue with the gauges/gauge pod?

Your oil should be fine. On an oil filter, the Wix or Napa Gold made by Wix is the one you want. Others don't seem to be preferred by the "Pontiac Gurus."

Your oil pressure is not the best, but it may also be a few pounds less than when it was located on the oil filter housing. I ran both on a 400CI and the dizzy pressure seemed to be about 5 PSI different.

If you bring your idle up a little, maybe 750, it may pick up. Pontiac rates their oil pressure at 2,600 RPM's. So it may be 30 PSI below this, but I would want 50-60 PSI @ 2,600 and above. Even though you may have a 60 PSI oil pump, it may show less.

Oil pressure can also drop as the engine gets worn in and clearance will open up a bit.

So my first move would be a mechanical gauge and you may find there is nothing wrong. A buddy of mine thought his chevy engine was blown as the oil pressure went south. I had him buy & hook-up a mechanical gauge and it was fine. His wiring was the problem.


----------



## bandit455 (Jan 31, 2017)

1968GTOMAN said:


> Hi my oil pressure is around 9PSI at idle it goes up to 60PSI when I first start the engine but after driving a few miles to a traffic light it will be 9PSI at idle.
> I still hear clicking, ( some may have seen my recent post about engine clicking.)
> The mechanics i know seem to go silent when i mention changing the oil pump, tube and screen, just as a maintenance thing, and it would rule that out as far as the cause. "If its like $600, lets do it." I say.
> Can i just pull off the oil pan and do it?
> ...


Pontiac’s typically run a higher oil pressure. 9 psi at idle is low for a warmed up engine and that rattle you hear is probably lifters pumping down.


----------



## Montreux (Mar 8, 2009)

Just a few comments/observations. 
1) If the fumes appeared after the carb was worked on or replaced, it’s not the rings causing it. 
2) Idle mixture will have negligible effect on full throttle power.
3) If the engine has a lot of miles, bearing clearances have opened up and oil leaks out faster>>lower oil pressure at idle. Try a higher viscosity oil. 10w30 was recommended for factory tolerances on new engines. I would move to a 20w50. 
4) If you’re not blowing blue smoke and fouling spark plugs, the rings aren’t totally dead. You might want to try Seafoam to “deep clean” the engine and possibly free up any stuck rings. Not a routine maintenance item, but might help if you’ve got 20 years of sludge built up in the engine. 
5) 87 octane in a 1970 Pontiac engine?!? Oh, hell no! You’re lucky if it runs on premium pump gas without additives!


----------



## 1968GTOMAN (Aug 3, 2020)

Yes i agree the fumes are the fault of carburetor settings.
Im not getting oil smoke, , oil stays clear, oil level stays consistent, last check.
Spark plugs on the carb setting PRE DYNO, were getting all black and roached.
Havent checked them post dyno.
An engine cleaning agent sounds like a good idea. Im not opposed to that provided it doesnt create more sludge than it removes or hurts anything?? You do make a good point about the decades of buildup, with no doubt neglect and improper combustion.
The 87 octane..if octane is an additive to slow down detonation for high compression engines, which has been explained very clearly by our panel of very experienced GTO Forum Gents, then why would my old engine, with supposed leaky rings and bearings benefit from that?
I put 87 in yesterday and it hummed along quite well. I dont want to disregard any well learned knowledge, so if there is a reason why you feel its bad to use 87 octane and the even 93 isnt good enough im sure its welcome to the table for discussion.
Please elaborate.
Thank you for your time and for your help.
Bill


----------



## 1968GTOMAN (Aug 3, 2020)

Just a fun pic, This was on my long driveway, the GTO on the way to the dyno. The way it was running then, only a week ago, was like pushing a saggy mattress on wheels.


----------



## Lemans guy (Oct 14, 2014)

Lust for speed gave you a very good summary of carb circuits. He is all spot on, I would just build on that be adding that from idle until about 2500 RPM’s your carb runs completely on the idle circuit. Which is your flour mixture screws and the transfer slots, which are controlled by the throttle screw. After about 2500 RPM’s the primary jets come on as lust4speed described in detail. They are in control then and although the idle circuit never stops pulling fuel it is such a small part at these RPM’s that it is negligible.

But you drive around in a street car a lot below 2500, and you could actually remove and plug the primary jets and drive all over under 2500 RPM’s. Now air bleeds can adjust when that transfer occurs, but it happens near that range unless changed.

So what you have done is to dial in your idle mixture, your operation from idle to about 2500 RPM’s to run a bit leaner. Your dyno run as lust described was at 12.8......that change has to be made to primary keys, power valve channel restrictions under the power valve and secondary operations with springs or throttle lever depending on carb.

12.8 seems a little lean to me, I would want and do 12.2.....for power


----------



## Mine'sa66 (Oct 30, 2019)

1968GTOMAN said:


> I put 87 in yesterday and it hummed along quite well. I dont want to disregard any well learned knowledge, so if there is a reason why you feel its bad to use 87 octane and the even 93 isnt good enough im sure its welcome to the table for discussion.
> Please elaborate.
> Thank you for your time and for your help.
> Bill


While it's unknown exactly what your engine is, it would seem a pretty safe assumption that it's something along the lines of a 1970 era Pontiac 400. That engine has a compression ratio that requires a certain octane level. The exact number is debatable, and the way octane is measured has changed since then. However, the number is far higher than 87.
What can go wrong? All sorts of things. Cracked pistons, bent valves, broken rings, fractured plugs to start the list.
Why did you have no _apparen_t symptoms?
Did you drain the tank? What were you running before? If you had a half tank of 93 in there and filled with 87, you made a mixture in between which may have been enough.
Good chance that you just didn't notice the subtle pinging going on. Could you identify that sound? How loud is your exhaust?
Another possibility is that you mentioned the heads might no be original. Perhaps someone's been in there and changed some things and the CR is a lot lower than what is started out as.
It's your car, you're planning on a new engine soon anyway, so blowing this one up may not be a tragedy.
IMHO, it would be sad to beak stuff for the sake of saving a few bucks on gas.
No matter what's going on, the ONLY benefit of using lower octane gas would be to save money.


----------



## CptTheAlex (Jul 17, 2015)

1968GTOMAN said:


> A gentleman on this thread said that if at least its consistent, 9psi at idle, but 50 to 60psi at speed then " Why worry?"
> Gave me some sleep after hearing that.


Yessir, after months and months of digging, i was able to sleep a little better. But every now and again, the 2 am demon of "lets rebuild" rears its ugly head.


----------



## CptTheAlex (Jul 17, 2015)

PontiacJim said:


> Thanks for the input and adding to the post. If you want, you can post a new topic on your engine and many here can help walk you through a few checks before having to pull the engine. But, I will throw a few things at you here.
> 
> As you noted, first verify with a mechanical gauge as the gauge, or even sending unit, can go bad. Sometimes it can be a ground issue when you install the sending unit - never put any sealer/sealant on it or it may not make that good ground. It uses a pipe thread that is self sealing as you tighten it up, but do not over tighten, especailly if you put it back at the filter or it will crack the fitting hole and you will need a new filter adapter.
> 
> ...


Thanks Jim! Hopefully it did not come off that i was trying to hijack a post. 

Yes, my thoughts exactly on testing with a mech gauge first, then checking power and ground (my electric choke is not working at the moment) and then lastly, replace the sensor (which is around $80 as im on my second one after i snapped the first one in half). 

Yep, i use the Wix / Napa filter always. 

Now that the weather is cooling off in NC, i've thought about messing with the Q-Jet carb Air/Fuel ratio again. I've read numerous places though that 650 is where a pontiac should idle at, what are your thoughts?

I'll create a post for myself here, as i have been meaning to do so for awhile and provide updates.


----------



## Old Man Taylor (May 9, 2011)

The key to your Octane issue is what heads do you have, and therefore what is your compression ratio. An engine requiring 91 Octane can self destruct using 87 Octane. An engine that is able to safely run 87 Octane can also safely run 91 Octane, it will just cost more money.


----------



## PontiacJim (Dec 29, 2012)

CptTheAlex said:


> Thanks Jim! Hopefully it did not come off that i was trying to hijack a post.
> 
> Yes, my thoughts exactly on testing with a mech gauge first, then checking power and ground (my electric choke is not working at the moment) and then lastly, replace the sensor (which is around $80 as im on my second one after i snapped the first one in half).
> 
> ...


Nope, not a hijacking as you were adding your experience to the post, but in asking your questions, and we like questions, it can create another spin-off within the original post and as it bounces back and forth in helping 2 members in the same post, it can get confusing, at least for me and my feeble mind. LOL So just start a fresh post and give us some details of what you have and your engine and ask away. We'll help and walk you through any issues in a manner you can understand and apply. Many good enthusiasts here on the forum who own, drive, and work on our Pontiacs (and other cars) - so its real world advice.


----------



## Jared (Apr 19, 2013)

Do us a favor and take a picture of one of the heads that is on your car. The important part is the middle section above the center exhaust ports. We can help you figure out what you have. Pontiac changed the casting all the time so the center stamping will narrow down what is on your car within a year or so.

As a side note. Nice looking car. I've personally always preferred the cars without the hide away headlights better.


----------



## 1968GTOMAN (Aug 3, 2020)

Old Man Taylor said:


> The key to your Octane issue is what heads do you have, and therefore what is your compression ratio. An engine requiring 91 Octane can self destruct using 87 Octane. An engine that is able to safely run 87 Octane can also safely run 91 Octane, it will just cost more money.


Really? , i thought if 87 didnt knock or rattle then its accepted by the engine. Figured the engine would tell you.


----------



## 1968GTOMAN (Aug 3, 2020)

Jared said:


> Do us a favor and take a picture of one of the heads that is on your car. The important part is the middle section above the center exhaust ports. We can help you figure out what you have. Pontiac changed the casting all the time so the center stamping will narrow down what is on your car within a year or so.
> 
> As a side note. Nice looking car. I've personally always preferred the cars without the hide away headlights better.


Me? I can if youre talking to me.


----------



## 1968GTOMAN (Aug 3, 2020)

1968GTOMAN said:


> Me? I can if youre talking to me.





1968GTOMAN said:


> Me? I can if youre talking to me.


Its a 242 GTO car, although the 4 is really weird in the vin. .. doesn't look tampered with but its just a bizarre shape, ill take a pic,, i should have in my phone though, ill look but if not ill show you the engine numbers and head numbers later today. Stayed up all night because i worked late and couldnt gravitate myself to bed.


----------



## 1968GTOMAN (Aug 3, 2020)

1968GTOMAN said:


> Me? I can if youre talking to me.


Look at the "4"


----------



## Jared (Apr 19, 2013)

1968GTOMAN said:


> Me? I can if youre talking to me.


Yes sir. A picture will help to figure out what you have.


----------



## Jared (Apr 19, 2013)

Just saw there was more. A picture of the cylinder head so we can help you to know what's been done on the engine. There is a big number or numbers and letters) right in the middle that dictates what era they came from and in some cases, what the approximate CR is.


----------



## Old Man Taylor (May 9, 2011)

1968GTOMAN said:


> Really? , i thought if 87 didnt knock or rattle then its accepted by the engine. Figured the engine would tell you.


That's exactly what I was trying to say. The problem is that if you try 87 Octane in an engine that doesn't like it, you might damage the engine during the trial.


----------



## 1968GTOMAN (Aug 3, 2020)

Old Man Taylor said:


> That's exactly what I was trying to say. The problem is that if you try 87 Octane in an engine that doesn't like it, you might damage the engine during the trial.
> Oh, i see, well ive run almost a full tank of 87 through it and noticed no ill effects. But have seen some white steamy gas smelling smoke at warm up


----------



## O52 (Jan 27, 2019)

Pictures of both heads would be nice.


----------



## 1968GTOMAN (Aug 3, 2020)

O52 said:


> Pictures of both heads would be nice.
> 
> View attachment 137363


Thanks will do!


----------



## Old Man Taylor (May 9, 2011)

Just an example of what can happen if you run an Octane rating lower than the demands of the engine. - - - 

I had a stock '70 GTO that I gave to my son in the mid-80's. I had driven it with no problem (at least I thought that), but I knew to stay away from the loads that caused detonation. My son is very hard of hearing, so he couldn't hear any engine noises. One time he said it wasn't running right. The symptoms seemed like bad spark plugs. I installed a new set with no improvement in the characteristics. I took the plugs out and did a compression test. Zero psi on #1 cylinder. So I took that head off hoping that a valve job would fix it. When I got it apart the intake valve was stuck open. There was a piece of piston ring, stuck between the valve and the seat. I don't know how it could do it, but a piece of the ring broke off and went past the piston top to get into the combustion chamber, and then get stuck in the valve. That meant the engine had to come out. That's what can happen running an Octane rating lower than the engine requires.


----------



## 1968GTOMAN (Aug 3, 2020)

Ah cool story, ! So he used low octane? Could that possibly have just been a coincidence?


----------



## Old Man Taylor (May 9, 2011)

No, he used 91 Octane, but the compression ratio was too high for 91. The engine was designed for something like 96 Octane. The advertised compression ratio was 10.75:1.


----------



## 1968GTOMAN (Aug 3, 2020)

Old Man Taylor said:


> No, he used 91 Octane, but the compression ratio was too high for 91. The engine was designed for something like 96 Octane. The advertised compression ratio was 10.75:1.


I dont know what to use then.


----------



## 1968GTOMAN (Aug 3, 2020)

O52 said:


> Pictures of both heads would be nice.
> 
> View attachment 137363


Sorry didnt make it out to garage today, was rainy and had to take care of work stuff.
I will provide the numbers tomorrow.
A thought a friend said a couple months ago that i have high pressure heads.
Ill let you know the numbers, thanks for your patience.


----------



## Jared (Apr 19, 2013)

1968GTOMAN said:


> Sorry didnt make it out to garage today, was rainy and had to take care of work stuff.
> I will provide the numbers tomorrow.
> A thought a friend said a couple months ago that i have high pressure heads.
> Ill let you know the numbers, thanks for your patience.


No worries. Take your time. Sounds like you work an odd schedule. I'm doing the same thing right now. I work 6am till noon and then need to be on call if my input is needed. The 2 hours from home have turned my day into a 12 hour work day. I miss being in the office full time. 

There is never a rush to answer right away.


----------



## 1968GTOMAN (Aug 3, 2020)

Jared said:


> No worries. Take your time. Sounds like you work an odd schedule. I'm doing the same thing right now. I work 6am till noon and then need to be on call if my input is needed. The 2 hours from home have turned my day into a 12 hour work day. I miss being in the office full time.
> 
> There is never a rush to answer right away.


Will you be able to tell by the numbers on the heads what compression its rated at, therefor surmise recomended octane to use?
Probably not, huh?


----------



## PontiacJim (Dec 29, 2012)

1968GTOMAN said:


> Will you be able to tell by the numbers on the heads what compression its rated at, therefor surmise recomended octane to use?
> Probably not, huh?


Yes.


----------



## 1968GTOMAN (Aug 3, 2020)

PontiacJim said:


> Yes.


Did you see the weird 4 on my vin?
How do you suppose that happened?


----------



## 1968GTOMAN (Aug 3, 2020)

Jared said:


> No worries. Take your time. Sounds like you work an odd schedule. I'm doing the same thing right now. I work 6am till noon and then need to be on call if my input is needed. The 2 hours from home have turned my day into a 12 hour work day. I miss being in the office full time.
> 
> There is never a rush to answer right away.


These pics are in my phone from when i was looking for numbers. Cant remember where exactly they were focused on.


----------



## 1968GTOMAN (Aug 3, 2020)

Thats the old carb, didnt mean to show that pic


----------



## O52 (Jan 27, 2019)

Looks like you have a 1970 400 block cast on Jan 9, 1970. 
If it hasn't been rebuilt the pistons are flat top with valve reliefs.


----------



## 1968GTOMAN (Aug 3, 2020)

I wonder if flat top pistons provide more compression.
Here are my head numbers


----------



## O52 (Jan 27, 2019)

It appears that both heads are the same from the dates but now we need the ID code over the center exhaust ports


----------



## O52 (Jan 27, 2019)

Your VIN looks like its been painted over before or maybe just a bad stamp. Heres mine for comparison


----------



## O52 (Jan 27, 2019)

Oh and heres an article I picked up somewhere regarding compression and octane 




*Octane, compression & detonation*

I grabbed several sources from both the internet and a few books to piece this together. The question of what octane should I use for my "X" compression *engine* seems to be an ongoing mystery. You can build your *engine* to any compression you want, but be aware of what octane you will need to run it and if you try to get by with an octane too low for a compression too high, know the consequences and the damage that can be done. There are always exceptions to the rule, but this should be a guide for the average Pontiac *engine* build. 

*Spark knock *(detonation) is an erratic form of combustion that occurs when multiple flame fronts occur simultaneously inside a combustion chamber and these multiple flame fronts collide, creating shock waves that produce a sharp metallic pinging or knocking noise. Detonation occurs because fuel is subjected to either too much pressure, too much heat or both. It usually happens during acceleration when the *engine* is heavily loaded and cylinder pressures are at their peak.

Mild detonation can occur in almost any *engine* and will not cause damage if the detonation is short lived. Prolonged heavy detonation is dangerous and can crack pistons and rings, blow out head gaskets, damage spark plugs and valves, and flatten rod bearings.

Detonation can be caused by a number of factors:

*Too Much Compression* for the octane rating of the gas being used or too low of an octane rating in an attempt to save money on the lower priced gas.

*Lean Fuel Mixtures*. Rich fuel mixtures resist detonation while lean ones do not. Air leaks in vacuum lines, intake manifold gaskets, carburetor gaskets can all allow extra air into the *engine* and lean out the fuel mixture. Lean mixtures can also be caused by a restricted fuel delivery, clogged carburetor jets, a restricted/dirty fuel filter, or a weak fuel pump. Air/fuel ratio can also be affected by changes in altitude.

*Overadvanced Ignition Timing* may create too much spark advance which causes cylinder pressure to rise too rapidly. If resetting the timing to stock specifications does not help, retarding timing a couple of degrees may be necessary to eliminate knock. Too much retard will also cause the *engine* to run hot.

*Engine Temperatures* can contribute to *engine* knock. A hot, or overheated, *engine* is more likely to suffer spark knock than one which runs at normal temperature - with normal temperature sometimes being a personal choice over the factory specified temps. Overheating can be caused by a clogged or too small a radiator, slipping belts, collapsed radiator hose, low coolant, a defective fan clutch, too hot a thermostat or a defective one, a bad water pump, etc.

*Overheated Intake Air.* With cars having thermostatically controlled air cleaners that provide the carburetor with hot air to aid fuel vaporization during *engine* warm-up, the air control door can stick shut so that the carburetor continues to receive heated air after the *engine* is warm, detonation may occur, especially during hot weather. Some cars have the hot air "stove" that directs heated air from off the exhaust manifold to the inlet on the air cleaner. A flexible tube/hose usually connects the two. It might be wise to remove the hose during summer operation.

*Spark Plugs* may be too hot. The wrong heat range plug can cause detonation as well as pre-ignition. Copper core plugs are less likely to cause detonation than standard spark plugs. You can experiment with heat ranges dropping down 1 or 2 colder steps. If too cold of a plug is used, the plug will experience fouling out as it isn't getting hot enough to burn off the deposits.

*Failure of Exhaust Gas Recirculation (EGR) System*. The EGR keeps combustion temperatures down, reducing the tendency to detonate. If the EGR valve is inoperative or someone has disconnected or plugged its vacuum hose, higher combustion temperatures can cause pinging.

*OCTANE* 

Octane does not offer any better fuel mileage, increase *engine* horsepower, or make the *engine* start quicker. Octane rating is a measure of a fuel's ability to resist *engine* ‘knock’ during combustion. The octane requirement of an *engine* varies with compression ratio, geometrical and mechanical considerations, and operating conditions. Higher octane gas burns slower, it is more resistant to knock when and *engine* is subjected to higher RPM's and cylinder pressures. Compression ratios factor into cylinder pressures. Higher ratios cause higher cylinder pressures and therefore cause the *engine* to be more susceptible to pre-detonation or knock. The higher the octane number, the more compression the fuel can withstand before detonating.

Tetraethyl lead used to be added to gasoline to prevent *engine* pre-ignition due to higher cylinder pressures associated with higher compression ratios by allowing the gas to burn more slowly and smoothly and to increase the higher octane requirements of the higher compression engines.

In 1962, the average octanes of gasolines in the U.S. stood at 93 for regular, 99 for premium and 102 for the few super-premiums on the market. The octane numbers increased slightly by 1967 as they reached around 94 octane for regular, and 100 for premium with the super-premium Sunoco 260 still being offered at 102 octane and advertised as the "highest octane pump gas." There were also other blends that had less octane than Regular and other grades between Regular and Premium.

The Clean Air Act of 1970 stipulated the federal mandates for automakers in reducing the emissions of their engines. GM reduced compression ratios on all of its 1971 engines to permit the use of low lead, regular leaded or unleaded gasolines and soon other automakers followed. This move spelled the end of the “octane race.” By 1974, unleaded gasoline was being phased in at most U.S. service stations as the catalytic converters used on the 1975 cars required unleaded gas only.

The 93 octane of today is only slightly less than the octane of the Premium pump gas of the 60’s and early 70’s. In the past, 100 advertised octane was common and Sunoco 260 gasoline was 102 octane. Those octane ratings sound high compared to today’s octane ratings, but they were not that much higher than you might think. Advertised octane in the past was based on a different measurement than used today.

There are 2 ways to rate octane, the “Research” octane number and the “Motor” octane number. The research octane number is a higher number than the motor octane number, so oil companies used to advertise their gasoline with the more impressive research octane number. The motor octane number is about 10 points lower than the research number.

In the early 70’s, the government decided to require oil companies to post an average of the 2 different octane ratings, which lowered the octane rating numbers for the same fuel that had had a higher number before. When you now look on a gas pump, you’ll see a sticker for the octane rating that says “R+M/2.” This stands for Research octane plus Motor octane divided by 2, which is the average of both octane numbers.

So the old Premium from the 1960’s that had a Research octane of 100 also had a Motor octane number of about 90. That same 100 octane Premium from the past would now be posted as the average of the 100 Research octane plus the 90 Motor octane, divided by 2 giving you a 95 octane rating. It is still a little higher than the 93 octane of today’s best Premium, but not as big a difference as most people think. The Sunoco 260 using this formula would have a 97 octane rating, which is quite higher than the best 93 octane Premium and higher still than the more common and readily available 91 octane found at most pumps.

So if you still have a factory *engine* with its 10.5 or 10.75 compression ratio, you can see how the pump 91 or 93 octane will be a problem and lead to detonation. It'll be almost impossible to tune this out when the solution is to use an octane gas or octane supplement to get the gasoline octane up between 97-100 octane.

In Jim Hand's Pontiac *engine* building book are a number of *engine* *builds* from an assortment of builders. In it they provide a compression ratio used by their *engine* build and a recommended octane needed to run the *engine*. Many factors do come into play that can effect a required octane number, but this gives you an idea. Here are a few of them:

Iron Head, 9.0:1, 91 octane minimum, 93 preferred
Edelbock Head, 9.5:1, 92 octane
Iron Head, 9.5:1, 93 octane
Iron Head, 9.3:1, 93 octane
Edelbrock Head, 10.5:1, 93 octane
Edelbrock Head, 9.7:1, 93 octane
KRE Head, 9.8:1, 93 octane
KRE Head, 10.0:1, 93 octane
Iron Head, 9.25:1, 92 octane
Iron Head, 9.4:1, 92 octane
Iron head, 9.5:1, 92 octane
Edelbrock Head, 10.25:1, 92 octane
Iron Head, 9.0:1, 93 octane
Iron Head, 9.5:1, 94 octane
Iron Head, 9.8:1, 94 octane

Three problems Ethanol can cause:

It is a Water Magnet - It will pull water out of the air right through your gas tank vent hose. In our high-humidity climate this can be especially harmful to your *engine*. As moisture is absorbed, the molecules of alcohol/water become heavier than the gasoline in the tank, and they settle at the bottom. This process is called "phase separation".

Unstable Octane Levels - Due to ethanol's high octane rating, if enough water is present in a fuel tank the ethanol can migrate to the water layer, dropping the octane level. This will leave you with lower octane fuel in the tank, and if the separated mixture becomes great enough to reach the fuel pickup tube, it will be sucked up into the *engine*, where it can clog filters, carburetor jets and fuel injectors.

Solvent Properties - If there is any gum or varnish build up in your old tank or fuel system, the alcohol will dissolve these deposits, and they will be sucked into the *engine* fuel system. If that weren't bad enough, the alcohol and water combination mentioned in #2 may also encourage the growth of bacteria in the fuel tank which turns into sludge and damages the fuel system.


----------



## 1968GTOMAN (Aug 3, 2020)

O52 said:


> Your VIN looks like its been painted over before or maybe just a bad stamp. Heres mine for comparison
> 
> View attachment 137416


AH!! Yeah! You can see that one part of the 4 is just missing on mine.


----------



## 1968GTOMAN (Aug 3, 2020)

O52 said:


> It appears that both heads are the same from the dates but now we need the ID code over the center exhaust ports


Are they original to to the 1970 engine ya think?


----------



## 1968GTOMAN (Aug 3, 2020)

1968GTOMAN said:


> Are they original to to the 1970 engine ya think?


Ill look. Thanks!


----------



## 1968GTOMAN (Aug 3, 2020)

Putting in midgrade today


----------



## O52 (Jan 27, 2019)

I'm guessing by the dates they're 69 heads. (K308 - Nov 30 1968) could be 79 though. Need that code to determine exactly what you have.


----------



## PontiacJim (Dec 29, 2012)

1968GTOMAN said:


> I wonder if flat top pistons provide more compression.
> Here are my head numbers


You really need to purchase a few books on Pontiac engines. This will answer many of your questions and get you familiar with your engine. Check out the book list:









FAQ - General: GTO and Pontiac Reference Sources


Surprised this has not been brought up - a suggested reading list for us Pontiac enthusiasts. Let's list any books, journals, factory literature, CD's, or other printed materials tht may be of value. And, it does not have to necessarily be Pontiac specific if it can be applied to out hobby...




www.gtoforum.com





Pontiac engines use flat top pistons. The compression is changed by the size of the combustion chambers, thus the need to know what heads you have on the engine which can be found on the middle exhaust port. The numbers you provided are the casting dates for the heads, not the head number. K=November, 20-day, 8=1968 making the heads 1969 because the new model year typically begins in September. 

Check out this listing for head casting codes. Look at the 1968 codes - like #16. It may be found in the 1969 head codes as well. So match up your head number with one on this chart and you will know what the heads are. To the right of the head code is the valve size and then the head chamber CC's. 72 CC's is high compression heads, typically 10.5 compression IF the pistons are stock flat top and have not been changed to a dished piston - which is not too likely if the engine has 20 years on it.



Pontiac V8 Cylinder Heads



High compression engines, such as the factory produced, really needs somewhere in the range of 98 Octane unless the timing is really retarded which means a loss of power potential.

It is possible that you have the low performance heads having smaller valves and the 8.6 compression which would mean you could use lower octane gas without issue.


----------



## 1968GTOMAN (Aug 3, 2020)

1968GTOMAN said:


> Are they original to to the 1970 engine ya think?





O52 said:


> I'm guessing by the dates they're 69 heads. (K308 - Nov 30 1968) could be 79 though. Need that code to determine exactly what you have.


Im going to look for the other numbers, do you think that if a 1968 engine blew while still under warranty back in 1969 or 70 that the factory would replace the block but reuse the heads if they were not damaged? Or would they have just switch with a complete engine?
Im fantasizing again about this GTO engine being a warranty replacement


----------



## 1968GTOMAN (Aug 3, 2020)

O52 said:


> Oh and heres an article I picked up somewhere regarding compression and octane
> 
> 
> 
> ...


This is great info! Thanks!


----------



## O52 (Jan 27, 2019)

More than likely but your heads are not original.


----------



## 1968GTOMAN (Aug 3, 2020)

O52 said:


> More than likely but your heads are not original.


Damn oh well, at least if i decide to get aluminum heads then i wont be upsetting the spirit world by committing sacrilege in separating original equipment.


----------



## PontiacJim (Dec 29, 2012)

1968GTOMAN said:


> Damn oh well, at least if i decide to get aluminum heads then i wont be upsetting the spirit world by committing sacrilege in separating original equipment.


Not being a smart butt, but I think you have a big learning curve before purchasing aluminum heads.


----------



## 1968GTOMAN (Aug 3, 2020)

PontiacJim said:


> Not being a smart butt, but I think you have a big learning curve before purchasing aluminum heads.


Im not doing the math on that. The guy who rebuilds motors will be calculating those figures. Im not pretending in the least to know.


----------



## PontiacJim (Dec 29, 2012)

1968GTOMAN said:


> Im not doing the math on that. The guy who rebuilds motors will be calculating those figures. Im not pretending in the least to know.


OK, just making sure you don't get yourself in hot water and make a goof in mismatching parts and walk away disappointed with the end results.


----------



## 1968GTOMAN (Aug 3, 2020)

PontiacJim said:


> OK, just making sure you don't get yourself in hot water and make a goof in mismatching parts and walk away disappointed with the end results.


Lol, well, i always have to do things twice, and that's even after consulting local experts. I try to do some research, i ask questions and opinions, then move ahead with their suggestions as in example, the single plain vs dual plane, or the mechanical vs vacuum secondary carbs, i do listen, and i try to do the best thing. In those cases i had to try both at some cost and single plane with vacuum secondary is best for this 1970 400.
As matter of fact the mechanic who will be doing the rebuild is saying my new holley 750 double pumper will be too small for the engine when he rebuilds it.
Im like "WHAT????????"


----------



## 1968GTOMAN (Aug 3, 2020)

1968GTOMAN said:


> Lol, well, i always have to do things twice, and that's even after consulting local experts. I try to do some research, i ask questions and opinions, then move ahead with their suggestions as in example, the single plain vs dual plane, or the mechanical vs vacuum secondary carbs, i do listen, and i try to do the best thing. In those cases i had to try both at some cost and single plane with vacuum secondary is best for this 1970 400.
> As matter of fact the mechanic who will be doing the rebuild is saying my new holley 750 double pumper will be too small for the engine when he rebuilds it.
> Im like "WHAT????????"


Sorry, I meant "Single plane and mechanical secondary is what works on this 1970 engine"


----------



## 1968GTOMAN (Aug 3, 2020)

O52 said:


> More than likely but your heads are not original.


Heres the pics of heads only numbers i see in middle 8 on drivers side and 4 and 8 on passenger side


----------



## PontiacJim (Dec 29, 2012)

1968GTOMAN said:


> Heres the pics of heads only numbers i see in middle 8 on drivers side and 4 and 8 on passenger side


Good heads. #48's are 1969 Ram Air III or 350CI HO heads. They are big valve, screw-in rocker arm studs. The 350CI version had slightly smaller combustion chambers to give a 10.5 compression while the same heads on a 400CI are said to be slightly larger to get the same 10.5 compression.

Either way, desireable heads for a Pontiac because of the cast #48 if doing a RA 400 engine or 350HO engine.

Here is a pair on Ebay just for example:









Pontiac Ram Air III Heads - Casting #48 | eBay


Find many great new & used options and get the best deals for Pontiac Ram Air III Heads - Casting #48 at the best online prices at eBay! Free shipping for many products!



www.ebay.com


----------



## 1968GTOMAN (Aug 3, 2020)

Wow! So you think they could be original to this 1970 engine?


----------



## O52 (Jan 27, 2019)

48 heads. Good news is that they're 69 heads used on the Ram Air III and the 350 High Output engines. Great heads. Bad news is they have the smallest combustion chambers (64 cc for the 350 and 72 cc for the 400) which means the highest compression and since they both have the same casting number you don't know which version you have until you measure the volume on the bench. Shaky for pump gas, even 93 octane. 
These didn't come with the block you have.


----------



## 1968GTOMAN (Aug 3, 2020)

phscollectorcarworld: ghost cars: 1968 Pontiac GTO Ram Air II
http://phscollectorcarworld.************/2015/08/ghost-cars-1968-pontiac-gto-ram-air-ii.html?m=1


----------



## 1968GTOMAN (Aug 3, 2020)

Can i knock out those fake hood scoops and build my engine "Ram air II" specs? or is that kinda dumb?


----------



## 1968GTOMAN (Aug 3, 2020)

O52 said:


> 48 heads. Good news is that they're 69 heads used on the Ram Air III and the 350 High Output engines. Great heads. Bad news is they have the smallest combustion chambers (64 cc for the 350 and 72 cc for the 400) which means the highest compression and since they both have the same casting number you don't know which version you have until you measure the volume on the bench. Shaky for pump gas, even 93 octane.
> These didn't come with the block you have.


My mechanic, i asked his position about this, he replied that it is his contention that pump gas is rated for up to 11.1 compression.
I wish there was a consensus.


----------



## 1968GTOMAN (Aug 3, 2020)

He says 11to 1, not 11.1


----------



## Old Man Taylor (May 9, 2011)

Maybe on a new car, but not on an old one that is not computer controlled.


----------



## 1968GTOMAN (Aug 3, 2020)

Old Man Taylor said:


> Maybe on a new car, but not on an old one that is not computer controlled.


His truck is in fact a new Dodge Ram. Good call, ill see what he says to that!
Thanks!!
I really appreciate the time you spend.
Bill


----------



## O52 (Jan 27, 2019)

Aluminum heads can take a bit more compression but with iron heads you're limited to 9.5 -1 without some attention to the type of cam you run. 
Ask him what he sets the cylinder quench to.


----------



## 1968GTOMAN (Aug 3, 2020)

Old Man Taylor said:


> Maybe on a new car, but not on an old one that is not computer controlled.


He replied, he says his is a 69 Dodge Dart, he wasnt talking about his truck like i thought.
Said its a truck motor w carb.
His text; My dodge is 10.5 . 1 hemi big cam headers every bolt on and I run 87 in it and it makes little over 400hp to the wheels


----------



## 1968GTOMAN (Aug 3, 2020)

Tha


O52 said:


> Aluminum heads can take a bit more compression but with iron heads you're limited to 9.5 -1 without some attention to the type of cam you run.
> Ask him what he sets the cylinder quench to.


Thanks!
Ill copy and paste this to him


----------



## Jared (Apr 19, 2013)

1968GTOMAN said:


> He replied, he says his is a 69 Dodge Dart, he wasnt talking about his truck like i thought.
> Said its a truck motor w carb.
> His text; My dodge is 10.5 . 1 hemi big cam headers every bolt on and I run 87 in it and it makes little over 400hp to the wheels


My guess is his Dart has a late model engine transplant, similar to putting a LS in one of our cars. If so, even with a carb it would still most likely have a modern ignition system and aluminum heads. Probably no issue at all running pump gas. Let's face is 400 hp in a modern V8 is probably pretty close to bone stock. My V6 pickup truck has 308hp.

There could be a lot of reasons why pump gas has not been an issue for your engine. You haven't had it very long and the previous owner may have been running an additive or race gas. I'm thinking that since your heads and block don't really match each other, it is very likely that your engine was rebuilt at some point in the past. Maybe when it was, they used a dish piston to lower the compression or a more aggressive cam (or both). None of this lines up with the power numbers you saw on the dyno so you very likely have a tired engine that may need a rebuild.

Side note on that. If you decide to rebuild what you have, there are a few things that you may find that will confirm that it was rebuilt at one point. Dished pistons would be a dead give away. Most good mechanics will ID stamp each component as an engine is torn down. The rods and pistons may have a location stamp somewhere on them so that the re-builder knows which cylinder each belongs to.

I have to give you credit here. Most guys would be pretty angry if they bought a car and it spent as much time in the shop as you have so far. You seem to have a pretty good attitude about this.


----------



## Lemans guy (Oct 14, 2014)

Get a cable camera, they sell for $20 bucks now...and look down a cylinder and see if you have dished pistons.....


----------



## 1968GTOMAN (Aug 3, 2020)

Where do you get those?
Ill google


----------



## Old Man Taylor (May 9, 2011)

They call them bore scopes.


----------



## 1968GTOMAN (Aug 3, 2020)

Old Man Taylor said:


> They call them bore scopes.


Kind that hook to your cell phone?
Like a USB?
I found something about that.


----------



## 1968GTOMAN (Aug 3, 2020)

1968GTOMAN said:


> Kind that hook to your cell phone?
> Like a USB?
> I found something about that.


I just ordered one be here Oct 3rd. I hope it works with my phone


----------



## O52 (Jan 27, 2019)

Ever hear back from the shop regarding quench requirements? Here's an article from Jim Hand (the Guru of Pontiac engines) to read up on. Two web pages






Jim Hand: Building A Strong Street Machine | Dallas Area Pontiac Association


Building a Strong Street Machine – Part 1: Introduction




www.dapa.org


----------



## 1968GTOMAN (Aug 3, 2020)

O52 said:


> Ever hear back from the shop regarding quench requirements? Here's an article from Jim Hand (the Guru of Pontiac engines) to read up on. Two web pages
> 
> 
> 
> ...


I never did get a response, it was Sunday night and he was understandably quiet, not very responsive. I'll follow up with him. I just dont know how to pose thecquestion, "What quench 


Jared said:


> My guess is his Dart has a late model engine transplant, similar to putting a LS in one of our cars. If so, even with a carb it would still most likely have a modern ignition system and aluminum heads. Probably no issue at all running pump gas. Let's face is 400 hp in a modern V8 is probably pretty close to bone stock. My V6 pickup truck has 308hp.
> 
> There could be a lot of reasons why pump gas has not been an issue for your engine. You haven't had it very long and the previous owner may have been running an additive or race gas. I'm thinking that since your heads and block don't really match each other, it is very likely that your engine was rebuilt at some point in the past. Maybe when it was, they used a dish piston to lower the compression or a more aggressive cam (or both). None of this lines up with the power numbers you saw on the dyno so you very likely have a tired engine that may need a rebuild.
> 
> ...


Yes im very interested in what parts remain as original in this engine.. yes it is a shame that im getting the car after it was worn out, but at least there are receipts that the trans was rebuilt and now that ive just had the rear rebuilt and the engine is running very nicely, im starting to get somewhere wiith this.
I love this car.. its my dream car. Its not ever going to be for sale i hope..


----------



## 1968GTOMAN (Aug 3, 2020)

O52 said:


> Ever hear back from the shop regarding quench requirements? Here's an article from Jim Hand (the Guru of Pontiac engines) to read up on. Two web pages
> 
> 
> 
> ...


----------



## 1968GTOMAN (Aug 3, 2020)

Im wondering if a 67 -68stock GTO camshaft is still available and is worth looking at? Is it too mild?


----------



## Jared (Apr 19, 2013)

1968GTOMAN said:


> Im wondering if a 67 -68stock GTO camshaft is still available and is worth looking at? Is it too mild?


The originals are most likely all gone but companies like Comp and others make cams that have the same specs as the original. It's just a matter of matching one up.

The specs for the 067 cam were 

273/289 duration, 197/213 0.050in duration, 0.410/0.410 intake/exhaust lift with 113 deg of lobe separation with 1.5 rockers

As far as it being too mild, that depends on what you plan on doing with it and what ci engine it's going in. It would be perfectly fine for a stock rebuild. Figure that is what Pontiac used in them from the factory and these cars were fast right out of the box.


----------



## Old Man Taylor (May 9, 2011)

The modern cams are cut with better profiles, so get one with the same kind of specs as the stock cam that you want.


----------



## 1968GTOMAN (Aug 3, 2020)

I just dont know what a stock cam feels and sounds like. Been decades since I rode in a stock 68 GTO.
A highschool friend, aquantance had one.
I dont recall it being really crazy aggressive.
Maybe he just was being careful for the cops.


----------



## O52 (Jan 27, 2019)

There are many clones for the older Pontiac cams. Melling sells a replacement 068 cam that's an excellent all around camshaft. Not crazy horsepower but nothing to be ashamed of either. This was the factory manual transmission cam for the 360 HP HO engine in 68 and the MT cam for the 350HP engine in 69. Jim Hand describes its performance in his tech article. 
Summit also sells their version of it too.


----------



## 1968GTOMAN (Aug 3, 2020)

So hey! I got the bore scope!
Works good!
Yeah, was only around $20 like you said.
Maybe Thursday ill have time to remove a spark plug, take and post a pic of piston to show if its dished.
I wonder if i could tell how bad the rings are work with that scope?
I appreciate everybody's help! Nice community here!
Thanks!
Bill


----------



## 1968GTOMAN (Aug 3, 2020)

1968GTOMAN said:


> So hey! I got the bore scope!
> Works good!
> Yeah, was only around $20 like you said.
> Maybe Thursday ill have time to remove a spark plug, take and post a pic of piston to show if its dished.
> ...


Worn, not work. Always a typo.


----------

