# Misfire 1971 Pontiac 455 YC Block



## Muranator66GTOCNVT (Oct 20, 2021)

So I have a misfire on cylinder number 7. The distributor was changed to a Delco Remy HEI. It ran fine when I bought it. I have changed wires, plugs, cap and rotor and still have a misfire on number 7 cylinder. I did a compression check on All the cylinders and it’s at 180- 185 psi across all cylinders. Number 7 cylinder was 183. I changed plugs that I know that were firing into number seven cylinder, and changed wires that I knew were firing and still when I pull the plug wire off of number 7 cylinder when it’s running there’s no difference. The engine still sounds the same with the same misfire. When I pull the plug in cylinder 7 it looks wet. What should the gap be on spark plugs on a 71 455? Any Help would be greatly appreciated


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## BLK69JUDGE (Jun 10, 2010)

I see you changed wires
can you run it in super dark conditions to watch for a spark leak ?


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## PontiacJim (Dec 29, 2012)

Muranator66GTOCNVT said:


> So I have a misfire on cylinder number 7. The distributor was changed to a Delco Remy HEI. It ran fine when I bought it. I have changed wires, plugs, cap and rotor and still have a misfire on number 7 cylinder. I did a compression check on All the cylinders and it’s at 180- 185 psi across all cylinders. Number 7 cylinder was 183. I changed plugs that I know that were firing into number seven cylinder, and changed wires that I knew were firing and still when I pull the plug wire off of number 7 cylinder when it’s running there’s no difference. The engine still sounds the same with the same misfire. When I pull the plug in cylinder 7 it looks wet. What should the gap be on spark plugs on a 71 455? Any Help would be greatly appreciated


Wet plug means it is not firing. Set gap to .040" for the HEI even though it can go wider. Smaller gap requires less energy to fire.

Make sure your wires are not touching and the spark energy is jumping to another plug wire.

You may have a dead wire - wires do go bad. Maybe a new set of wires?

On the outside chance, you could have a valve out of adjustment and seeing the plug is wet, it would make sense the intake is working, but maybe the exhaust is not. Maybe a rocker arm has backed off, and gone sideways, so the exhaust valve is not working.


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## Muranator66GTOCNVT (Oct 20, 2021)

PontiacJim said:


> Wet plug means it is not firing. Set gap to .040" for the HEI even though it can go wider. Smaller gap requires less energy to fire.
> 
> Make sure your wires are not touching and the spark energy is jumping to another plug wire.
> 
> ...





PontiacJim said:


> Wet plug means it is not firing. Set gap to .040" for the HEI even though it can go wider. Smaller gap requires less energy to fire.
> 
> Make sure your wires are not touching and the spark energy is jumping to another plug wire.
> 
> ...


Yes, today after posting I checked the temperature on the exhaust manifold for cylinder seven and it wasn’t as hot as the others. I was thinking I would pull the valve cover off and check valve adjustment as my next step. Thank You for the advice. I’ll let you know what I find out


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## Muranator66GTOCNVT (Oct 20, 2021)

BLK69JUDGE said:


> I see you changed wires
> can you run it in super dark conditions to watch for a spark leak ?


I will check tomorrow evening. Thank You


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## Muranator66GTOCNVT (Oct 20, 2021)

PontiacJim said:


> Wet plug means it is not firing. Set gap to .040" for the HEI even though it can go wider. Smaller gap requires less energy to fire.
> 
> Make sure your wires are not touching and the spark energy is jumping to another plug wire.
> 
> ...


So today I took the valve cover off and turn the engine over and watch the valves open and close. Both intake and exhaust are opening and closing properly. Valve adjustment looks good. I got my Infrared thermometer out and took Exhaust readings. At low idle cylinder 7 exhaust temperature is very low compared to the others cylinders, but at high idle it starts the exhaust temp goes up on number cylinder 7. 
Any other Ideas Why #7 cylinder is miss firing at lower RPM’s?


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## integrity6987 (May 10, 2017)

Muranator66GTOCNVT said:


> So today I took the valve cover off and turn the engine over and watch the valves open and close. Both intake and exhaust are opening and closing properly. Valve adjustment looks good. I got my Infrared thermometer out and took Exhaust readings. At low idle cylinder 7 exhaust temperature is very low compared to the others cylinders, but at high idle it starts the exhaust temp goes up on number cylinder 7.
> Any other Ideas Why #7 cylinder is miss firing at lower RPM’s?


Are you super-triple sure the distributor cap is seated properly? Get a spark plug wire tester or pull the plug wire and see if it will arc to the ground. Maybe pull the plug and keep it on the wire to the ground to inspect the spark.


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## Mine'sa66 (Oct 30, 2019)

Guys, he said the misfire developed and then he changed all his secondary ignition components. So unless he took off a bad wire and put another bad wire right back on, odds are the issue lies elsewhere.
So.....valve train looks good from the outside....at least it's moving.
Next step?
I think I might do a leakdown test to see how well the valves are actually seating.
What are you running for an intake?


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## geeteeohguy (Feb 2, 2008)

Leakdown test is a good idea as well as a 'running compression test'. I have found flat exhaust lobes on camshafts doing a running compression test when the regular static compression test showed 170 psi in every hole. #7 was dead and it only showed up doing a running compression test. This was a '78 Chevy 305. Worn exhaust lobe on the cam.


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## BLK69JUDGE (Jun 10, 2010)

Amazon.com: Lisle 20610 Inline Spark Tester : Everything Else


Amazon.com: Lisle 20610 Inline Spark Tester : Everything Else



www.amazon.com





nice to have one of these in your toolbox

you can watch the spark and see if its intermittent


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## BLK69JUDGE (Jun 10, 2010)

if consistant ,,,, exhaust valve lobe or lifter went away 
no rocker arm ticking ???
stock rockers ??? non adjustable


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## PontiacJim (Dec 29, 2012)

Muranator66GTOCNVT said:


> So today I took the valve cover off and turn the engine over and watch the valves open and close. Both intake and exhaust are opening and closing properly. Valve adjustment looks good. I got my Infrared thermometer out and took Exhaust readings. At low idle cylinder 7 exhaust temperature is very low compared to the others cylinders, but at high idle it starts the exhaust temp goes up on number cylinder 7.
> Any other Ideas Why #7 cylinder is miss firing at lower RPM’s?



OK, let's recap what has already been done.

*Delco Remy HEI.* It ran fine when I bought it.

1.) Changed wires, plugs, cap and rotor

2.) Compression check on All the cylinders and it’s at 180- 185 psi across all cylinders. Number 7 cylinder was 183.

3.) Changed (swapped) plugs that I know that were firing into the number 7 cylinder.

4.) Changed (swapped) wires that I knew were firing to the number 7 cylinder

5.) Engine still sounds the same *with the same misfire*. When I pull the *plug in cylinder 7 it looks wet*.

6.) Took the valve cover off and turn the engine over and watch the valves open and close. Both intake and exhaust are opening and closing properly. *Valve adjustment looks good. *

Single cylinder won't fire, all others do.

If bad electronic module, it would be bad and all cylinders affected.
If bad coil, it would be bad and all cylinders affected.
If bad rotor, it would affect all cylinder.

Bad cap - cracked, poor quality where brass electrode is not extended far enough to make good contact with the rotor, drilled/positioned too far away from rotor to make contact.
--When you re-attached the coil to the top of the cap, did you use the same screws? Make sure none of the screws have gone through the top of the cap and are not sticking through causing a short.
---Check the center electrode in the cap - should have a curved surface that makes contact with the rotor button and should be able to move in/out against the spring - you did replace this with a new one, right?.

Since it was running well with the old parts, install the old cap and try that.

Rotor. May be bad. Make sure the contact that connects with the center electrode in the cap is making solid contact with it. I have had to lift up on that rotor contact because it was a cheap thin strip of metal and did not have a good enough bend in it to make solid contact with the cap electrode. Some of them can have the metal contact that signals your spark to the cap's electrode be too short and the gap can be too large for the spark energy to jump it and fire the plug.
---Check the distributor shaft that the rotor sits down onto. It could be bent or have a bad bushing causing a wobble and possibly creating a large air gap that the spark can't jump - so check the distributor shaft for wiggle/play.

The Reluctor wheel that triggers the plugs to fire could be bad or grounding out. There are 8 "teeth" and do the same thing as points do in a points distributor. One of them could be bad/bent/grounding or who knows what - I know nothing about factory HEI's.

You checked the rocker arms and the valve adjustment looked good. Looking good is not the same as the adjustment is good.  The valve could be hanging open just a hair and you would not be able to see that. With the engine running, "Zero Lash" number 7 cylinder to make sure the valves are fully closing. Do a forum search and you will find how to "zero lash" your lifters. Watching the valve operation could also show a lifter not working correctly. Put a white mark on each pushrod where you can see it. When the engine fires up, the pushrod should be spinning and the white mark will be easier to see. It could take a little more than idle to get it to spin, but not much. If the pushrod is not spinning, this can mean the valve lifter is not spinning on the cam lobe - which is should do. No spinning could mean a bad cam lobe.

Just an odd problem to be sure since all other cylinders are firing. Do a few more checks/tests and give us the results.


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## Muranator66GTOCNVT (Oct 20, 2021)

BLK69JUDGE said:


> if consistant ,,,, exhaust valve lobe or lifter went away
> no rocker arm ticking ???
> stock rockers ??? non adjustable


No ticking, stock rockers which are adjustable. 
I pulled the valve cover off and rotated the engine and both intake and exhaust valves move up and down equally like the rest on that bank. I am going to do a leak down test sometime this week when I get time. Like I said it starts firing at higher RPMs because the exhaust temp goes up just like the rest at higher revs but not at idle


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## MHOpus (Jul 13, 2009)

PontiacJim said:


> OK, let's recap what has already been done.
> 
> *Delco Remy HEI.* It ran fine when I bought it.
> 
> ...


Is the distributor 180 degrees out?


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## Lemans guy (Oct 14, 2014)

Double check your firing order as well and the inside contacts on the plug wires. Put an ohm meter on #7 spark plug wire to make sure of resistance even new wires can be bad. Wires can crossfire with each other also. So separation is good. Also make sure that #7 is not routed to close to a vacumn hose or the power brake booster. You can switch plugs wires but they can arc to a short thru metal or the carbon black on a hose.

yes rotor and HEI’s coils can short in side only on one contact. Look inside the cap and under for any carbon tracking. HEI were notorious for tracking and arcing under there.

Also a misfire can be caused by a vacumn leak at the intake runner. It misses at high idle vacumn, then as throttle opens and vacumn drops that small vacumn leak is absorbed into the bigger rush of air from the throttle so it does not have as big an effect on the mixture in that cylinder. I would be carefully checking for a vacumn leak at that rear intake runner near #7.

If the Air fuel ratio (AFR) is too lean at idle the plug won’t fire. It needs hydrocarbons to fire under pressure and you have cylinder pressure, but maybe a bad AFR.

Smoke machine is the best way to detect this. Drive to a neighborhood garage that you like and ask them to hook up the smoke to the intake and watch all over, but particularly near that runner. They should not charge too much for that and before you throw more parts at it,mit may be worth a try. Bring a very bright flashlight, you need it to see the smoke.

Good luck and let us know how you do


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## Muranator66GTOCNVT (Oct 20, 2021)

Thank You for the help and ideas Guy’s. I will do this process of elimination. Hopefully I find what’s causing this misfire on # 7 cylinder


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## Muranator66GTOCNVT (Oct 20, 2021)

Muranator66GTOCNVT said:


> Yes, today after posting I checked the temperature on the exhaust manifold for cylinder seven and it wasn’t as hot as the others. I was thinking I would pull the valve cover off and check valve adjustment as my next step. Thank You for the advice. I’ll let you know what I find out





PontiacJim said:


> Wet plug means it is not firing. Set gap to .040" for the HEI even though it can go wider. Smaller gap requires less energy to fire.
> 
> Make sure your wires are not touching and the spark energy is jumping to another plug wire.
> 
> ...


Hi Jim,
I finally got around to doing a leak down test on number 7 cylinder. I have 5% leakage on number 7 cylinder and I know for sure the intake valve is leaking as the air was coming out from the carb. I haven’t removed the head yet. Do you think this maybe a timing issue? Do you think Pinging caused the valve to go bad? I never heard any pinging while driving or under heavy throttle. What should the timing be? 
Thank You


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## PontiacJim (Dec 29, 2012)

Muranator66GTOCNVT said:


> Hi Jim,
> I finally got around to doing a leak down test on number 7 cylinder. I have 5% leakage on number 7 cylinder and I know for sure the intake valve is leaking as the air was coming out from the carb. I haven’t removed the head yet. Do you think this maybe a timing issue? Do you think Pinging caused the valve to go bad? I never heard any pinging while driving or under heavy throttle. What should the timing be?
> Thank You


Reading your post again, I have another question. What does "stock rockers which are adjustable" mean? Stock rockers use a nut which gets torqued down to 20-25 ft lbs, they are not adjustable. Please explain this - stock rockers as in factory stamped steel 1.5 ratio rocker arms, press-in or screw-in studs, factory rocker arm studs, poly locks instead of the factory nuts?

I would back the adjustment off on the intake valve. I pointed this out earlier - "zero lash" the lifters. You cannot look at the rocker arms and determine they are good because they all appear to operate the same. Not all rocker arms are the same exact ratio, a pushrod might be off, a valve may have been ground down/dressed on the top stem if a valve job was done, a valve can be sunken deeper than others during a valve job.

You may just have the 1 valve too tight. If you can hear air back flowing, back the rocker arm adjusting nut off so the rocker is loose. If you don't hear any air, then it is an adjustment. If you do hear air, then you have a valve/head problem. You could have worn valves/seats, a bent valve, a cracked valve, a piece missing if somehow something got sucked into the cylinder and bounced around getting caught under the valve, the valve hanging up on the valve guide, a weak/incorrectly installed valve spring height not applying enough pressure to seat the valve completely closed, OR a cracked head.

Pinging, or detonation, is not always heard. Often you will hear it very audible under load where the engine has to really grunt to get the car moving. But you can also have detonation at higher speeds/RPM that is masked by engine/exhaust sound. Timing too far advanced, low octane, high engine/cylinder temps can be causes you may not necessarily hear.

Detonation can sometimes show up on the nose insulator of the spark plug. If you use a magnifying glass to observe the insulator around the center electrode, you may see aluminum flecks/speckles. This is an indication that metal bits are being shed/melted from the pistons. Not good. So this can be a means to identify a problem.

Many factors can affect the timing on your engine - each engine is different and this has to take into consideration the driveline - trans & rear end gear ratio's. With iron heads, I always suggest Intial to be around 10-12 and 32-34 degrees total mechanical, vacuum advance disconnected, and all in around 3,200 RPM's. That is a base line as you can go up or down on the RPM's as well as the Total advance. Camshaft selection, Compression, Octane, and how the carb is jetted (rich or lean), and Exhaust choices can all be factors. Once you get the mechanical set where there is no pinging, engine temps are not too high, does not labor to turn over when starting, and has some pep, then you have to bring in the vacuum advance and dial that in by knowing how much additional timing it provides at high vacuum conditions.

So no easy 1 size fits all and this is why the factory used a generic and conservative tune on their engines so as to cover a number of bases rather than tune each engine/car individually. The region the car was going to be sold in also has bearing - higher/lower altitude, dry/damp climate, hot/cold weather types, etc., so a general tune setting covered a broad spectrum of adverse conditions. It was also for warranty purposes - the general tune was less likely to cause engine conditions that broke parts/pieces or took out an engine.

So if me, I would first do as I stated in backing off the rocker arm on the leaking valve and see if that does it. If it does, you could just choose to "zero lash" the valves and see if that cures the problem. If the valve stopped leaking, but "zero lash" did not cure the problem, then I might remove the spring on that valve (maintaining air pressure on the cylinder to keep the valve seated and not dropping down), secure the valve so it will not drop down once air pressure is removed/leaks down on the cylinder. You can re-pressurize the cylinder when you are ready to re-install the spring.

Take the spring down to the local machine shop and they should have the installed height specs for your year engine/head and they can test both the open installed height spring rate and closed spring rate. If it is not in spec, then you know you need new springs and they should be able to help you out in ordering what you need. Springs can go weak over time from excessive engine heat, over revving, or just a defective spring.

If the valve still leaks and you are 100% sure you can hear it through the carb with the rocker arm backed off, then I think I would pull the head and get to the root of the issue rather than take a chance that a problem I could solve rather easily becomes a problem that damages the engine - you don't want a valve snapping off the stem and dropping into the cylinder.


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## Muranator66GTOCNVT (Oct 20, 2021)

Thanks Again Jim,
I will try the steps you explained before pulling engine. If I do pull engine I will rebuild it. 
The motor has adjustable rockers(Allen rocker stud style adjustment with lock nut). Screw in rocker studs with oiling through push rods. Unfortunately I bought the car with no records of the engine build. It was a good buy considering it only had 22,000 original documented miles on the body. Original 389 cracked from sitting in a barn on a wood floor from 1966-99. I guess California cars didn’t get strong enough anti freeze in cars that would be in sub zero climate. Anyway… so last owner put a 1971 455 YC Engine in the he rebuilt. He sold it through a classic car dealership so I didn’t get any info on the engine other than pictures of it being built.


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## PontiacJim (Dec 29, 2012)

Muranator66GTOCNVT said:


> Thanks Again Jim,
> I will try the steps you explained before pulling engine. If I do pull engine I will rebuild it.
> The motor has adjustable rockers(Allen rocker stud style adjustment with lock nut). Screw in rocker studs with oiling through push rods. Unfortunately I bought the car with no records of the engine build. It was a good buy considering it only had 22,000 original documented miles on the body. Original 389 cracked from sitting in a barn on a wood floor from 1966-99. I guess California cars didn’t get strong enough anti freeze in cars that would be in sub zero climate. Anyway… so last owner put a 1971 455 YC Engine in the he rebuilt. He sold it through a classic car dealership so I didn’t get any info on the engine other than pictures of it being built.


OK. Then my money would be on the poly lock being incorrectly adjusted just a little too tight and holding the valve open just enough so it does not seat tightly.

When you back the poly lock nut off on the #7 intake and test for an air leak,and that does it, I would "zero lash" all the lifters/rockers on that side and then do the other side to ensure whoever installed them knew what they were doing. This is done while the engine is running for the best results - in my opinion & experience. Others adjust the lifters differently than with the engine running.

You also want to make sure you have the correct length body on the poly lock - they can be long or short. Look at the allen screw. It should not be sunk into the poly lock, nor should it stick way up and out. You want the allen screw to be somewhat flush at the top or just a thread or 2 above.

Here are a couple posts to read through that will help.









torquing rocker arms


I am putting my 326 back together and I have question on torqueing my rocker arms. The manual says to torque to 20#. Do I just go down the line and torque them all to 20 or doe the need to be preloaded and if so how do you preload.




www.gtoforum.com













Compress lifters by hand - normal?


Hi gang, long time no post. I had my motor re-built quite a few years ago (2012). It sat till I finished my resto in 2015. Strong running, no leaks, plugs burning clean. I have been getting considerable lifter tap from the left bank and was preparing to do a cold engine overlap adjustment using...




www.gtoforum.com













Rocker Arm / possible collapse lifter??


Hello all - I have a conundrum here. My new complete rebuilt motor for 68' GTO, 400 MT came back with ticking noise I attributed to a loose rocker arm or bad lifter. After numerous consults, I adjusted all the rocker arms per the "twist push rod until tension and snug down 180deg. - NOT the...




www.gtoforum.com


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## Muranator66GTOCNVT (Oct 20, 2021)

PontiacJim said:


> OK. Then my money would be on the poly lock being incorrectly adjusted just a little too tight and holding the valve open just enough so it does not seat tightly.
> 
> When you back the poly lock nut off on the #7 intake and test for an air leak,and that does it, I would "zero lash" all the lifters/rockers on that side and then do the other side to ensure whoever installed them knew what they were doing. This is done while the engine is running for the best results - in my opinion & experience. Others adjust the lifters differently than with the engine running.
> 
> ...


Hey Jim,
I checked # 7 cylinder today…valve cover off. Made sure it was at top dead center for that cylinder. Hooked up leak down tester. Noticed that the air was coming out around the intake pushrod hole as well. That seems odd to me…cracked head Or blown head gasket? Not losing any antifreeze or compression. 
I took rocker arm off completely and no change on leak down…still at 5%.
Guess I know what my winter project is


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## geeteeohguy (Feb 2, 2008)

5% leakdown is totally acceptable. In fact, it's excellent. At 20% and more you have issues. Odd you are getting air out of the pushrod hole....that leads right into the lifter valley in the block, and is not head related. Normal leakage past the rings allowing air into the crankcase and out the pushrod hole perhaps?


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## PontiacJim (Dec 29, 2012)

Muranator66GTOCNVT said:


> Hey Jim,
> I checked # 7 cylinder today…valve cover off. Made sure it was at top dead center for that cylinder. Hooked up leak down tester. Noticed that the air was coming out around the intake pushrod hole as well. That seems odd to me…cracked head Or blown head gasket? Not losing any antifreeze or compression.
> I took rocker arm off completely and no change on leak down…still at 5%.
> Guess I know what my winter project is


Wow, I gotta say I am baffled on this one. If you had air coming from the pushrod hole, that is specific. If it were leaking past the piston/ring and out the block as *geeteeohguy* noted, it would be heard across any/all pushrod and oil drain holes.

And no other cylinder does this, just the #7 ?

The pushrods have no connection to the cylinders so there is no way that air would be coming out a pushrod hole. Looking at a head, the head gasket would have to break through/crack at the pushrod area to let any air past. It is possible the gasket is intact around the water passages, but somehow blown out right at that area.

Squirt some light oil into the #7 cylinder at the back wall so the oil will run down along the rings and create a seal. The compression pressure usually will go up when doing this test, but see if that changes the air sound when you apply air to the cylinder.

If the cylinder holds pressure for an extended period, then things are being sealed up and your valves/rings are in good order. Some leakage can be normal and is not an issue as the engine wears.

Bad head gaskets usually have other signs like water in the oil, oil in the water, or 2 adjacent cylinders with equally low compression/cylinder pressure. A cracked head could be cause, but most I have seen are usually between the intake/exhaust valve in the center where they are the closest.

Any gasoline smell if you check the oil? 

Maybe use a bore scope and look in that cylinder.

I am running out of checks to do and would hate to see you pull the head and not find anything, but that may be the last resort just for piece of mind.


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## Muranator66GTOCNVT (Oct 20, 2021)

PontiacJim said:


> OK. Then my money would be on the poly lock being incorrectly adjusted just a little too tight and holding the valve open just enough so it does not seat tightly.
> 
> When you back the poly lock nut off on the #7 intake and test for an air leak,and that does it, I would "zero lash" all the lifters/rockers on that side and then do the other side to ensure whoever installed them knew what they were doing. This is done while the engine is running for the best results - in my opinion & experience. Others adjust the lifters differently than with the engine running.
> 
> ...


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## Muranator66GTOCNVT (Oct 20, 2021)

PontiacJim said:


> OK. Then my money would be on the poly lock being incorrectly adjusted just a little too tight and holding the valve open just enough so it does not seat tightly.
> 
> When you back the poly lock nut off on the #7 intake and test for an air leak,and that does it, I would "zero lash" all the lifters/rockers on that side and then do the other side to ensure whoever installed them knew what they were doing. This is done while the engine is running for the best results - in my opinion & experience. Others adjust the lifters differently than with the engine running.
> 
> ...


Hi Jim,
So today with a cold engine took the spark plug out of number 7 cylinder, loosened rockers completely, sprayed some oil in there and did the leak down test. Leak down percentage was at 8%. That’s higher than the 5% I had last time. Also As you remember I was thinking I was getting air up around number 7 cylinders pushrod. Well I decided to spray some soapy water along the intake. Guess what… bubbles started coming from in between the intake and the head on number 7 cylinder with air applied to number 7 cylinder. That’s where I felt the air🙄
So Intake gasket bad. 
So then I thought I would do the spraying of the oil in 7 cylinder with the engine hot. 
I started the engine with the valve cover off and noticed that it was not getting any oil up through the pushrods onto the rockers. I rev the engine to about 2500 RPMs and still no oil. It wasn’t until the oil and engine got warmer (about 10-15 seconds) than the oil started coming up through the pushrods onto the rockers. That does not seem right to me.
So I did leak down on the hot engine with with rockers completely loose and got 8% leak down. Not sure why it’s higher this time. I did drive it to put fuel the day before. I did do zero lash on that cylinder. Checked the others and they were fine 
I got a winter project I guess. 
what’s so funny is when I drive it, the engine runs strong and smooth, you wouldn’t even know there was something wrong until you come to idle and that’s when you notice the miss.


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## PontiacJim (Dec 29, 2012)

Muranator66GTOCNVT said:


> Hi Jim,
> So today with a cold engine took the spark plug out of number 7 cylinder, loosened rockers completely, sprayed some oil in there and did the leak down test. Leak down percentage was at 8%. That’s higher than the 5% I had last time. Also As you remember I was thinking I was getting air up around number 7 cylinders pushrod. Well I decided to spray some soapy water along the intake. Guess what… bubbles started coming from in between the intake and the head on number 7 cylinder with air applied to number 7 cylinder. That’s where I felt the air🙄
> So Intake gasket bad.
> So then I thought I would do the spraying of the oil in 7 cylinder with the engine hot.
> ...


OK, not sure why the change in the leak down with/without oil. Intake gasket seems odd as I am trying to figure how air can get past the valve and pressurize the intake passage. Still could be a cracked head?

You should have had oil pressure the pretty much the second the engine fired. Things to consider would be clogged oil pump pick-up screen if the engine had the nylon coated cam gear and the nylon bits began to deteriorate and fall off into the oil pan - it can clog the pick-up screen, faulty/wrong oil filter, oil too thick, worn oil pump, worn bearings having too much clearance, lifter bore restrictors, pushrods with the smaller holes to hold back oil, rocker arms too loose/too tight, collapsed lifter.

Did you think to observe the pushrods to see that they were all spinning with the engine running?

Have you checked your oil pressure? New oil filter? What brand? What oil weight? Most likely if the engine has never been rebuilt, you have the factory 40 PSI oil pump. So don't expect to see 55-60 PSI. If your oil pump is failing, or not pumping enough oil from the pan, then it would not provide the needed oil pressure going to the lifters and if the lifters were not being fully oiled, this could affect the opening of the intakes and exhaust valves.

What about the wet spark plug & misfire?

Post a photo of your rocker arms/poly locks with the valve cover off. I want to see what you have. Heads should be #66?


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## Muranator66GTOCNVT (Oct 20, 2021)

PontiacJim said:


> OK, not sure why the change in the leak down with/without oil. Intake gasket seems odd as I am trying to figure how air can get past the valve and pressurize the intake passage. Still could be a cracked head?
> 
> You should have had oil pressure the pretty much the second the engine fired. Things to consider would be clogged oil pump pick-up screen if the engine had the nylon coated cam gear and the nylon bits began to deteriorate and fall off into the oil pan - it can clog the pick-up screen, faulty/wrong oil filter, oil too thick, worn oil pump, worn bearings having too much clearance, lifter bore restrictors, pushrods with the smaller holes to hold back oil, rocker arms too loose/too tight, collapsed lifter.
> 
> ...


Thank You Jim,
The leaking was coming from the intake runner going to the intake valve not from the pushrod hole like I thought. They are close to one another so it felt like it was coming from pushrod rod hole. As far as I know the engine was rebuilt. It was stated in the description when I bought it. I don’t know if he did the whole motor or just the top end. Restoration pictures show the guy installing the cam. Supposedly it was dyno’d as well but I don’t have that paperwork.
As far as the pushrods, they are spinning when it’s running. I had checked that earlier in my investigation. It has a oil light, no gauge. So I will need to do pressure check. I will send pictures tomorrow


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## PontiacJim (Dec 29, 2012)

Muranator66GTOCNVT said:


> Thank You Jim,
> The leaking was coming from the intake runner going to the intake valve not from the pushrod hole like I thought. They are close to one another so it felt like it was coming from pushrod rod hole. As far as I know the engine was rebuilt. It was stated in the description when I bought it. I don’t know if he did the whole motor or just the top end. Restoration pictures show the guy installing the cam. Supposedly it was dyno’d as well but I don’t have that paperwork.
> As far as the pushrods, they are spinning when it’s running. I had checked that earlier in my investigation. It has a oil light, no gauge. So I will need to do pressure check. I will send pictures tomorrow


OK do what you can. I am always leary when I hear someone else rebuilt the engine because without paperwork or the name of the shop who did the work, you don't know the extent of the rebuild and what has been done and how well were things checked. You could have the wrong length pushrods. You could have a bad gasket or cracked head. You don't want to assume the worst as there are many who are honest. But honest mistakes happen and there are a lot of enthusiasts who want to assemble their own engines after the machine shop has done their work. If they do, you don't know their skill level and how meticulous they checked all their clearances.

So in all reality, it may not be a bad idea for a winter project to pull down the top end and inspect your heads, cam, lifters, measure pushrod lengths, etc. and know what exactly you have. If all looks good you can add your gaskets and button it up. But, if any issues, you will find them and go from there rather than guess or take a chance on engine damage.

If you do tear it down, make sure you take a lot of pics as you go step by step and tag/bag your removed parts so you know what/where they go back. If you are like me, you will tear it apart and not get to re-assemble for another 3-4 months and try to figure out what goes where. LOL I take a lot of pics and use a lot of zip lock bags for my parts.


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## geeteeohguy (Feb 2, 2008)

8% leakdown is just fine. No problem with your rings or cylinder.


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## Muranator66GTOCNVT (Oct 20, 2021)

Hi Jim,
Here’s some photos of the engine and rockers and 6X Heads. In the 3rd photo I circled exactly where the air is leaking. Right above the number 7 cylinder intake pushrod.
I did remember when I change the oil two weeks ago all I had was the 5 quarts of the 10w-30 Lucas hot rod oil and I added that thick Lucas oil stabilizer additive to the oil. Maybe it’s too thick? I am buying straight oil and new filter for today and see if that cures the cold start up no oil problem.
The last photo is of the ad for the car. Said motor was Professionally built. Which doesn’t mean anything really. You would think if they built the motor professionally they would’ve put I new oil pump in.
View attachment 157565

View attachment 157564

View attachment 157566

View attachment 157563
View attachment 157567



PontiacJim said:


> OK do what you can. I am always leary when I hear someone else rebuilt the engine because without paperwork or the name of the shop who did the work, you don't know the extent of the rebuild and what has been done and how well were things checked. You could have the wrong length pushrods. You could have a bad gasket or cracked head. You don't want to assume the worst as there are many who are honest. But honest mistakes happen and there are a lot of enthusiasts who want to assemble their own engines after the machine shop has done their work. If they do, you don't know their skill level and how meticulous they checked all their clearances.
> 
> So in all reality, it may not be a bad idea for a winter project to pull down the top end and inspect your heads, cam, lifters, measure pushrod lengths, etc. and know what exactly you have. If all looks good you can add your gaskets and button it up. But, if any issues, you will find them and go from there rather than guess or take a chance on engine damage.
> 
> If you do tear it down, make sure you take a lot of pics as you go step by step and tag/bag your removed parts so you know what/where they go back. If you are like me, you will tear it apart and not get to re-assemble for another 3-4 months and try to figure out what goes where. LOL I take a lot of pics and use a lot of zip lock bags for my parts.


Thanks Jim! 
Yeah, I’m pretty meticulous when I take down an engine. Tons of pictures and lots of heavy duty zip lock bags with labels. 
Im still concerned about the oil pressure.

I change oil today to straight 10w-30 and will start tomorrow with cold engine and valve covers off. I did loosen all rockers on each side, one side at a time. Then tighten until the ticking stopped and tightened the poly lock. Still have a slight tick not bad. I noticed when the rockers were loose the oil flowed very nicely after the engine was hot. 
I’ve always done Chevy engines. On Pontiac with these type rockers What do you recommend for adjustment of rockers on a running engine? How many turns after the ticking stops?
I was also thinking if there was an intake leak on cylinder #7 that would cause a lean condition that could have taken out the intake valve?
I guess I’ll find out when I take it apart. Thank goodness I still have the other GTO to play with in case these one doesn’t get done before next spring. Shop and schedule times are way out on their schedules. Thanks again!


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## PontiacJim (Dec 29, 2012)

Muranator66GTOCNVT said:


> Hi Jim,
> Here’s some photos of the engine and rockers and 6X Heads. In the 3rd photo I circled exactly where the air is leaking. Right above the number 7 cylinder intake pushrod.
> I did remember when I change the oil two weeks ago all I had was the 5 quarts of the 10w-30 Lucas hot rod oil and I added that thick Lucas oil stabilizer additive to the oil. Maybe it’s too thick? I am buying straight oil and new filter for today and see if that cures the cold start up no oil problem.
> The last photo is of the ad for the car. Said motor was Professionally built. Which doesn’t mean anything really. You would think if they built the motor professionally they would’ve put I new oil pump in.
> ...


The attachments did not take, as I got an "Ooops!" message.

10W-30 should work and the Lucas stabilizer should not have any affect. Anytime I add anything thicker to an oil, I add it when the engine is hot and running so it flows better and then mixes thoroughly. I used the STP oil treatment in my brother's old truck which calles for 40W oil, so a can went in with the Rotella 15W-40.. The STP also has some ZDDP in it according to the label.

When you "zero lash" the rockers, you tighten slowly until the clicking stops, BUT, give it about 15-20 seconds for the lifter to adjust itself as the oil has to bleed down and find its correct level. The lifter may start ticking again, then you tighten just enough to stop the ticking and let it "normalize" again. You may only have to make 1 adjustment or it could be 3 adjustments until the ticking is gone and the valve lifter where it wants to be, Then turn 1/4 turn, tighten the st screw, and hold the set screw and with the wrench turn another 1/16 of a turn just to cinch the poly lock down.

If you have the correct poly lock length, the allen set screw should be just slightly above the nut. If it is sunk too deep, the poly lock body is too long and you could be loosing adjustment as the allen screw bottoms on the threads and not the stud. If the set screw shows a lot of thread, then the poly lock is probably too short and you are not grabbing enough of the threads inside the poly lock and you can strip out the set-screw or it can go out of adjustment because it is not getting a good enough "bite" to hold it secure on the stud.

Put a dab of white paint or something on the tops/side of each pushrod so you can see the rod spinning. Sometimes you cannot tell as some rods will spin very fast and others may just sit there and not spin and you think they look like they are. The ones that are not spinning are a problem. This can mean too tight, or see if you raise the RPM's a bit if they begin to spin. You should be able to grab the pushrod and spin it by hand with the engine running. If not, it is too tight and you want to back off the rocker arm to see if that gets it spinning.

The looser the rocker arm, the more oil will flow out the rocker arm spurt hole - this is what you want. The oil might be a little sluggish at idle RPM's, but still flow fairly well. I always go 1/4 turn on the poly lock after the clicking stops on my last adjustment. Some will say 1/2 turn or 1 full turn. Who knows? I go 1/4 turn and this has always worked, and the pushrods spins nicely and oil flows out the rockers. Too tight on that last lock down turn, 1/2 or 1 full, can compress the valve plunger too much and add too much pressure on the pushrod and the oil doesn't seem to flow as well and the pushrod labors to spin. Pushrod spinning means the valve lifter is spinning on the cam's lobe as it was designed to do or the lifter would simply sit on the cam lobe and wear the bottom of the lifter/cam lobe out - that is how they are designed.

I don't think a lean condition would damage the intake as it is the exhaust that takes all the heat as it goes out, so a lean condition would more likely do damage over a period of time and some hard running like a long pull up a mountain with a 40-foot camper behind you and a tractor trailer on your butt intimidating you to go faster (no that was not me, or was it? LOL). The soap bubbles could be simply from a bad gasket that is bad enough to allow the incoming intake charge to have enough force/pressure to allow air to escape. Bigger cams with more overlap can have revision characteristics where some of the intake charge is pushed back up into the intake during overlap - which gives the cam that nice idle sound we all want to hear. 

If it is an intake problem, then there could be a number of reasons from a poor valve job on the seat, a poor cut on the valve, or a poor machining of the valve guide where it affected the valve placement or angle. So I don't think end of the world problem, might be real simple and a machining error that can be easily fixed. Hopefully you have all new stainless steel valves and the heads were not rebuilt with the stock valves as the stainless being new would give better/wider margins for a better seating/sealing. If the stock valves were used and re-ground, the margins could be thin or the valve sunk deeper into the head if the shop was trying to make what they had work because the owner did not want to spend the budget to do the job correctly. Heads could have been purchased on Craig's List already done up and at a good price and were not rebuilt well (or *some scumbag* pulled them off his engine because they were cracked and sold them as recently rebuilt and he was installed E-heads instead), so all kinds of scenario's.

All part of this hobby, and if you don't like working/tinkering on a car, then this hobby is not for you, OR you had better have the wallet to pay another to work/maintain your car and not squawk when the bill arrives (I don't have the wallet, just some loose change). I am not a motorcycle rider, but it has always been told me that if you own a Harley, you want to keep a tool bag with it and you own it knowing you like to adjust/work on them. So same principal.

Just keep at it and don't let it get you frustrated. It's a learning process that you can later share with others who may need your experiences.


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## Muranator66GTOCNVT (Oct 20, 2021)

PontiacJim said:


> The attachments did not take, as I got an "Ooops!" message.
> 
> 10W-30 should work and the Lucas stabilizer should not have any affect. Anytime I add anything thicker to an oil, I add it when the engine is hot and running so it flows better and then mixes thoroughly. I used the STP oil treatment in my brother's old truck which calles for 40W oil, so a can went in with the Rotella 15W-40.. The STP also has some ZDDP in it according to the label.
> 
> ...


Thank You Jim for all your help. Much appreciated. Next time I buy a classic car if the motor was rebuilt, I’m getting paperwork and parts list. That doesn’t always make up for someone’s inexperience building it, but helps to know what your working with.
That’s half the fun of owning these cars, is tinkering 
btw…I keep a tool bag in the trunk😊


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## Baaad65 (Aug 29, 2019)

Tool bag...hell I have a whole tool box complete with duct tape, bailing wire and halon fire extinguisher plus an extra coil, bulbs,
jumper cables and all kinds of tools 👍


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## PontiacJim (Dec 29, 2012)

Baaad65 said:


> Tool bag...hell I have a whole tool box complete with duct tape, bailing wire and halon fire extinguisher plus an extra coil, bulbs,
> jumper cables and all kinds of tools 👍
> View attachment 157670


Yep, always a good thing to have some tools if you can use them. It is also nice to have a few parts that you may not be able to readily get at a parts store if you get stuck out on a drive.

Ignition and fuel are the two culprits that can leave you stranded. If points, extra set of quality points/condensor, if electronic, extra module and heat sink grease. I usually save the cap/rotor/couple spark plugs from any last tune-up and toss this in the trunk. I also like to keep an extra coil-to-distributor wire if I change out wires - these have gone bad on me, but very rare. I know they worked, just time to replace them, so I hang on to them. You can source a coil easy enough.

An extra fuel filter is a good idea. If the fuel pump or anything else major goes bad, then you are most likely not going to be swapping it out on the side of the road.

With a Pontiac, I used to keep and extra starter solenoid with me. The heat can cook these and I have replaced my share in parking lots. A manual shift car is not quite a problem as you can push start the car easy enough.

I keep a tire plug set in the car - Walmart sells these. Have a set of needle nose pliers if you get a nail in the tire and have to pull it out. Then just plug the hole with the tire plug kit. Another handy item is a hose coupling kit that has several sized plastic tubes where you can cut a leaking/busted hose, insert the coupler, use the hose clamps, and be on your way - providing you have some anti-freeze in the trunk. A can of Instant Start.

And lastly - AAA or some other break-down/towing service.


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## Bopman (7 mo ago)

PontiacJim said:


> OK, let's recap what has already been done.
> 
> *Delco Remy HEI.* It ran fine when I bought it.
> 
> ...


Sounds like a bad relucter had the same thing happen on a 350 buick, drove it a while with a miss then later a second cylinder went to missing......put a point distributor in it and all cylinders went hitting like they were supposed too !


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## Muranator66GTOCNVT (Oct 20, 2021)

PontiacJim said:


> Yep, always a good thing to have some tools if you can use them. It is also nice to have a few parts that you may not be able to readily get at a parts store if you get stuck out on a drive.
> 
> Ignition and fuel are the two culprits that can leave you stranded. If points, extra set of quality points/condensor, if electronic, extra module and heat sink grease. I usually save the cap/rotor/couple spark plugs from any last tune-up and toss this in the trunk. I also like to keep an extra coil-to-distributor wire if I change out wires - these have gone bad on me, but very rare. I know they worked, just time to replace them, so I hang on to them. You can source a coil easy enough.
> 
> ...


Yep I keep adding different things to my tool bag. I have tied if down just in case Someone does a dumb maneuver in front of me…like having to swerve. Happened to me. Had a small battery pack fly around and put an ever so small of a dent in the rear quarter panel that i could see from the outside. Body shop was able to massage it out thank goodness.


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## geeteeohguy (Feb 2, 2008)

Bopman said:


> Sounds like a bad relucter had the same thing happen on a 350 buick, drove it a while with a miss then later a second cylinder went to missing......put a point distributor in it and all cylinders went hitting like they were supposed too !


I have been spouting this same information for years to the masses on pretty much all the car forums. It goes mostly unheard and ignored. That said, I never have suffered ignition problems with all my points and condenser cars and let the guys who 'upgraded' theirs enjoy the tow truck and pissed off wife. 👍


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## Baaad65 (Aug 29, 2019)

Muranator66GTOCNVT said:


> Yep I keep adding different things to my tool bag. I have tied if down just in case Someone does a dumb maneuver in front of me…like having to swerve. Happened to me. Had a small battery pack fly around and put an ever so small of a dent in the rear quarter panel that i could see from the outside. Body shop was able to massage it out thank goodness.


My tool box is bolted down 👍


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## Muranator66GTOCNVT (Oct 20, 2021)

geeteeohguy said:


> I have been spouting this same information for years to the masses on pretty much all the car forums. It goes mostly unheard and ignored. That said, I never have suffered ignition problems with all my points and condenser cars and let the guys who 'upgraded' theirs enjoy the tow truck and pissed off wife. 👍


We have a Points Distributor master/Guru in our GTO group. He’s like skillful surgeon with this points distributor’s and when you have them set right they are the best option. He has all the old equipment to tune these points distributor’s. Looks like the NASA computer boards from back in the 60’s. He has said 
These factory points distributors are master pieces in how they are built and work. He says hands down points distributor is far better than HEI. More times then not. HEI will fail before points distributor.


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## geeteeohguy (Feb 2, 2008)

I've said this over and over, so I'll be short. I tuned cars for a living for years. I can't count the number of cars that were towed in that did not run due to a fried module or pickup coil. From old wrecks to near new cars. I can count on one hand the number of tow in's with points simply because they were flat worn out. 
HEI is maintenance free and you can get different timing curves and have rev limiters, etc. But you will not make more power with an HEI, particularly at high RPMS. Look up Lars Grimsruud's articles or watch Uncle Tony's Garage on youtube. Good stuff!


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## Mine'sa66 (Oct 30, 2019)

geeteeohguy said:


> I've said this over and over, so I'll be short. I tuned cars for a living for years. I can't count the number of cars that were towed in that did not run due to a fried module or pickup coil. From old wrecks to near new cars. I can count on one hand the number of tow in's with points simply because they were flat worn out.
> HEI is maintenance free and you can get different timing curves and have rev limiters, etc. But you will not make more power with an HEI, particularly at high RPMS. Look up Lars Grimsruud's articles or watch Uncle Tony's Garage on youtube. Good stuff!


I stood in front of a Sun scope for a decade, them stood in front of a Bear scope for another 2 decades when fuel injection came along.
I agree 100% with this.
Digital is great, until it's not.
Analog requires input from you, but YOU are in charge of the situation.


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## Baaad65 (Aug 29, 2019)

So just curious how does my MSD R2R dist with the reluctor wheel compare, better or worse or the same as HEI, I know it's electronic with a module.


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## geeteeohguy (Feb 2, 2008)

Mine'sa66 said:


> I stood in front of a Sun scope for a decade, them stood in front of a Bear scope for another 2 decades when fuel injection came along.
> I agree 100% with this.
> Digital is great, until it's not.
> Analog requires input from you, but YOU are in charge of the situation.


I started in '79 on a Sun 1015 with the manual cyl cancel and real time scope, Computerized cars came into play in '80, learned all that stuff with feedback carbs....moved to a Coats 460, spent years on a Bear Pace 400 (what a GREAT machine!) and ended up with an Allen Smartscope that was a total downgrade from the Bear. 
Ended up finishing my career with Bear and Sun equipment, as well as Hunter. Good stuff.
Cars went from carbs to electronic carbs to fuel injection to DIS ignition, etc. all on my watch. Things were totally different from the beginning to the end of my career. Cars went from serviceable analog repairable/restorable items to throw-away appliances. 
Ford had module failures and TFI (Thick Film Ignition) failures of their HEI
Chrysler's systems had mainly magnetic pickup failures in the distributor
GM had ignition module failures, coil-in-cap failures, and module wire fatigue failure in the distributor.
When I started out, most of the cars I worked on had points and condenser ignition. By the time I finished, the only points to be seen were on my personal car in the parking lot out front.


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## Mine'sa66 (Oct 30, 2019)

geeteeohguy said:


> I started in '79 on a Sun 1015 with the manual cyl cancel and real time scope, Computerized cars came into play in '80, learned all that stuff with feedback carbs....moved to a Coats 460, spent years on a Bear Pace 400 (what a GREAT machine!) and ended up with an Allen Smartscope that was a total downgrade from the Bear.
> Ended up finishing my career with Bear and Sun equipment, as well as Hunter. Good stuff.
> Cars went from carbs to electronic carbs to fuel injection to DIS ignition, etc. all on my watch. Things were totally different from the beginning to the end of my career. Cars went from serviceable analog repairable/restorable items to throw-away appliances.
> Ford had module failures and TFI (Thick Film Ignition) failures of their HEI
> ...


I started about 4 years after you. Lots of boo-hooing when we went from Sun to Bear. Then after a couple years, it was obvious which was the better equipment.
I tell the exact same story...brothers from another mother lol.


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## Bopman (7 mo ago)

geeteeohguy said:


> I have been spouting this same information for years to the masses on pretty much all the car forums. It goes mostly unheard and ignored. That said, I never have suffered ignition problems with all my points and condenser cars and let the guys who 'upgraded' theirs enjoy the tow truck and pissed off wife. 👍


I hear ya ! 😉👍


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