# 69 400 motor - couple questions



## jholodniuk (Nov 29, 2010)

I just picked up a 69 motor with 3000 miles. 
L2262 pistons, 0.030 over.
What is up with the cylinder walls? Should I re-hone and put new rings or is this not something to worry about? You can't feel any of it, just looks like oxidation. What causes this?

Also, on my 71 400 engine under the oilpan there was a windage tray, my 69 does not have this. Should I put one or is it not necessary?

4x 2.11 and 1.77 valves, 98cc. I used a CR calculator, and depending on head gasket thickness and if I measured deck height correctly it should be a 8.7:1 to 9.1:1, I think. What cam would you guys recommend? It has stock 4bbrl intake and Qjet carb. TH400 tranny with 2800 stall, gears I plan on using 3.42's with a 28-29" tall tire. Or is there a better choice for gears? I plan to hit the strip a few times a year. I will be driving it in the city and on occasional 400km trips. Its in a 1970 GTO.


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## jholodniuk (Nov 29, 2010)

Not sure how to upload photo, its only 1mb but after 10 mins it is still uploading?


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## BearGFR (Aug 25, 2008)

jholodniuk said:


> I just picked up a 69 motor with 3000 miles.
> L2262 pistons, 0.030 over.
> What is up with the cylinder walls? Should I re-hone and put new rings or is this not something to worry about? You can't feel any of it, just looks like oxidation. What causes this?
> 
> ...


On a 400 with those heads, that sounds about right for compression ratio, but let me encourage you to actually measure the chamber volumes yourself. Actual volumes can vary quite a bit from the nominal factory specs. What did you measure your decks to be?

On the windage tray deal, some engines had them and some didn't. Use information at this web site to confirm what you really have and what heads it would have had originally. The purpose of a windage tray is to try to prevent the spinning crankshaft from picking up a big glob of oil and spinning it around - sometimes referred to as an "oil cloud". Having a tray is good for performance because it reduces drag on the crank. Most 69 high performance engines would have had one, so that would make me wonder what your 69 400 is out of.
Starting with a 400 for a performance build is a good idea because those blocks are stonger than 455's (and 428's). The main webs are stronger due to the smaller main journals.
A very common approach is to bore the block to 4.155 (.035 over stock), put in an aftermarket 4.250" stroker crank, and viola - you've got a 461. Depending on your budget and how far you're willing to stray away from "factory original look", building a 461 that makes 550+ horsepower and will run all day on 93 octane fuel is very doable - using aftermarket aluminum heads and a "good" cam/valvetrain. I recently built my numbers-matching 400 from my 69 into a 461. I'm running iron heads, factory intake, quadrajet, headers, and a moderate solid roller cam. It dyoned at 492HP @ 5200, 543 ft. lb. of torque @ 3100, it stays above 500 ft. lb. all the way though 5200 rpm, and to the casual observer it looks like a stock 400. Here's a link to the dyno sheet
Let me recommend someone to you: Jim Lehart at Central Virginia Machine. He helped me plan my engine, and though I did wind up buying most of my parts from him he was very willing to help and to explain the rationale behind his recommendations long before I ever committed to spend a nickel. He's a good guy and he definitely knows his Pontiacs. He'll help you put together a plan to set and reach your goals based on what matters to you.

Bear


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## jholodniuk (Nov 29, 2010)

Deck height I measured was .030", but I only did one piston and I think it was number 5. Seems I read online you gotta measure a few and be sure to measure 1 and 2. I did measure the chambers myself and came up with 98cc. I got an old headgasket with the motor and it measured 0.050" thick, I never measured the new gasket yet to see what it starts out as, but .050" seems awful thick to me. The new gaskets that came with it are FelPro.

I plan to just run this 400 for a year or two then sell it to my uncle for his 71 firebird, and built a 461/462 outta my 71 lemans 400 block that needs a rebore anyway. I will check the numbers on the block to see what it really came out of, it didn't matter to me as my car is the furthest thing from numbers matching, and I could are less for numbers matching. 
I'm 23yrs old and just finishing up university, and started this frame off this past May. I'm just building a fun old car to rip around in and take to the track once a few times a year.


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## jholodniuk (Nov 29, 2010)

And thanks very much for the info on your 461, as well as about the windage tray!


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## geeteeohguy (Feb 2, 2008)

Goof advice from Bear. As a side note, I'd have to see your cyl. walls to make a call on their condition. You need a decent hone crosshatch to seat new rings, and the crosshatch has to be compatable with your particular ring material (iron, chrome, etc,). Also, on your compression: I am running the original 400 in my '67 GTO, which I rebuilt in 1988 with the same pistons as you're using. Mine is punched '030 just like yours. I am running 87cc heads (1970 #15) that cc'd out to 87 after the valve job. I am barely at 9:1 compression. I can run on 87 octane without pininging, though when it's hot I run 89. With your 98cc heads, you're looking at maybe 8:1 compression, a tad low, IMO. Compression isn't everything, but it does help with power, economy, and throttle response. My advice would be to mill the heads to get down to 90cc or less, or perhaps get some better heads. If you mill them too much, you will have to mill the intake to match and experiment with push rod length. If I were to do it again, I would have milled my 87cc heads down to 84 or 82cc. Good luck with your build.


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## BearGFR (Aug 25, 2008)

jholodniuk said:


> Deck height I measured was .030", but I only did one piston and I think it was number 5. Seems I read online you gotta measure a few and be sure to measure 1 and 2. I did measure the chambers myself and came up with 98cc. I got an old headgasket with the motor and it measured 0.050" thick, I never measured the new gasket yet to see what it starts out as, but .050" seems awful thick to me. The new gaskets that came with it are FelPro.


From the factory, Pontiacs "generally" have deck heights in the neighborhood of .020 so, you're in the ballpark there. You're right about it being better to measure them all to be sure. "Zero decking" the block is good for combustion efficiency and quench (and can actually help keep you out of detonation) as long as it doesn't put your static compression ratio too high for your cam/fuel. "Standard" Pontiac head gaskets are usually .040 to .045 when torqued/compressed (the only measurement that matters) so your measurement of .050 for an uncompressed gasket is also in the ballpark.


To post photos here you have to store them on a web server (your own, or a public photo repository like photobucket.com) and then use the URL of the photo in your post.

Have fun - just think about what you're doing and why, and remember that the whole drive train has to be designed to work together. (A big lumpy high-rpm cam will fall flat on it's butt with a 1500 rpm stall converter)


Bear


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## jholodniuk (Nov 29, 2010)

Made a photobucket acct. Hope the link works.

Pictures by jholodniuk - Photobucket

Picture of the cylinder from the top and bottom, a pic of the heads after new valves and seats installed, and a pic of the motor. The guy said he fogged it when he pulled it, could that be fogging oil residue on the cyilnders? My dad said you can feel the crosshatch with your fingernail still, I never noticed, but I know you cannot feel the "oxidation look" with your finger. Not sure what it is??

Also, the cam that is currently in the car is a Lunati #00071. 230/230 at 0.050 lift with a 110lsa. Any good? I'm looking for other opinions so I can change it before I drop it in the car over Christmas.


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## freethinker (Nov 14, 2009)

jholodniuk said:


> I just picked up a 69 motor with 3000 miles.
> L2262 pistons, 0.030 over.
> What is up with the cylinder walls? Should I re-hone and put new rings or is this not something to worry about? You can't feel any of it, just looks like oxidation. What causes this?
> 
> ...


according to the picture of the cylinder that engine has way more than 3000 miles on it. you have it apart. i would rering it.


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## 66tempestGT (Nov 28, 2009)

have you seen it run? if i took mine apart this far i would probably hone it and stick some rings in it.


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## jholodniuk (Nov 29, 2010)

Ya I have not seen it run, guy told me it only had 3000 miles but I disagree with that as well. Rings and a hone job won't cost much, I was also thinking might as well do it since its this far apart anyway. I'm by no means an engine person thats why I thought I'd ask here if anyone knew what the oxidated look is from.


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## BearGFR (Aug 25, 2008)

jholodniuk said:


> Ya I have not seen it run, guy told me it only had 3000 miles but I disagree with that as well. Rings and a hone job won't cost much, I was also thinking might as well do it since its this far apart anyway. I'm by no means an engine person thats why I thought I'd ask here if anyone knew what the oxidated look is from.


How long has it been sitting apart like that and how long has it been since it ran? Could be just plain old surface rust starting. I'd rub some oil in there to and turn it over a few times to spread it to help guard against more.

That Lunati cam is one I'd call a "mild" hydraulic. It's not as "big" as the factory Ram Air IV cam, for example. With the same duration/lift on intake and exhaust it's probably going to be a little deficient on the exhaust side. It should have a reasonable idle and make enough vacuum for power brakes. 

Bear


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## jholodniuk (Nov 29, 2010)

geeteeohguy said:


> I am running 87cc heads (1970 #15) that cc'd out to 87 after the valve job. I am barely at 9:1 compression. I can run on 87 octane without pininging, though when it's hot I run 89. With your 98cc heads, you're looking at maybe 8:1 compression, a tad low, IMO. Compression isn't everything, but it does help with power, economy, and throttle response. My advice would be to mill the heads to get down to 90cc or less, or perhaps get some better heads. If you mill them too much, you will have to mill the intake to match and experiment with push rod length. If I were to do it again, I would have milled my 87cc heads down to 84 or 82cc. Good luck with your build.



Weird, I just used a different compression ratio calculator with the same values I had gotten 8.7:1 with, and got 7.8:1. I gotta find that other calculator again and see if I just plugged a wrong value in the first time.

98cc heads
8cc valve relief
.05 HG thickness
.02-.03 deck height
4.15" bore, 4.18" HG? 
stock stroke (3.75")

Well I put in 8cc for valve relief, but I think I was supposed to punch in -8. Getting 7.8/7.9:1. Can I safely cut them down to 84cc and the intake will still bolt on properly? Any way to know for sure, or measure?


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## BearGFR (Aug 25, 2008)

jholodniuk said:


> Weird, I just used a different compression ratio calculator with the same values I had gotten 8.7:1 with, and got 7.8:1. I gotta find that other calculator again and see if I just plugged a wrong value in the first time.
> 
> 98cc heads
> 8cc valve relief
> ...


I just plugged your numbers into my own spreadsheet I use:
4.150 bore, 3.750 stroke, 98cc chambers, 8 cc valve relief, .042 compressed gasket, 4.160 gasket bore (that's what they usually are), .020 deck, and I calculate 7.942:1. If you zero-deck the block and run .036 Cometic gaskets that becomes 8.293:1 - and you get the extra benefits of better quench, better combustion efficiency, and more resistance to detonation. Replace those pistons with some good forged flat-tops (usually have around 6 cc's in the reliefs) that puts it at 8.42:1. Cut the heads enough to knock those chambers down to 87 cc's and you're at 9.231:1 - but as you mentioned you'll probably have manifold fitment issues cutting them that much. 

Or... scour around and find yourself some 6X-4 heads and you're there (making the other mods but not milling the heads)

Or... pop for a set of good 87 cc aluminum heads, do the other mods also, and make boatloads of power - plus you've got triple 'detonation insurance' (aluminum heads, zero deck, reasonable compression).


Like Indy racer A.J. Foyt once said: "Speed is just a question of money. How fast do you want to go?" 

Bear


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## jholodniuk (Nov 29, 2010)

Looks like I should have never bought this motor in the first place. Should have rebuilt my 71 Lemans 400 and done it how I wanted. Would have been cheaper in the long run haha. Oh well, you live and learn. This one will do for now. Will I even make 300hp with 7.9:1?


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## BearGFR (Aug 25, 2008)

jholodniuk said:


> Looks like I should have never bought this motor in the first place. Should have rebuilt my 71 Lemans 400 and done it how I wanted. Would have been cheaper in the long run haha. Oh well, you live and learn. This one will do for now. Will I even make 300hp with 7.9:1?


Contrary to popular belief, compression only doesn't make a huge difference. On my motor the difference between 9.4:1 and 10:1 would only be about 8 HP. There's nothing wrong with what you've got, really. It just depends on what you want to do with it for what you've got to spend. If it were me and I wanted to keep it really on the cheap, I'd go find a set of 6x-4 heads from a salvage yard. Then I'd get a moderate flat-tappet hydraulic cam, or maybe even a solid flat tappet cam if you don't mind having to readjust your valves a couple times a year. Remember any time you change a flat tappet cam you also have to replace the lifters and pushrods, and fresh valve springs wouldn't be a bad idea. The upper limit on how "much" cam you use will be determined by factors such as the idle quality you want, whether you have and want to still be able to use power brakes, rear gear ratio, torque converter (if an automatic) etc. Before assembly I'd have a machinist who knows Pontiacs tank-clean the block, hone the cylinders with a torque plate, square the decks, and align-hone the mains. I wouldn't zero deck it for version 1.0 just because if you decide to build it into a stroker at some point in the future you might NEED those few thousandths to keep the compression down. I'd have him put in fresh freeze plugs and fresh cam bearings while I was at it and leave the cam with him and tell him to make sure after he "does" the cam bearings that the cam spins freely.
Expect all those operations on the block to run you around $500.

Get your grinder out and using your new intake manifold gaskets as a guide, shape the ports in both the heads and the intake manifold to exactly match the size and shape of the gasket openings. Make sure any material that you have to remove, you blend back into the port for at least an inch. If you don't have tools to remove/install valve springs, then do that before you take the heads up for the valve job. That way the machine shop can do all the cleaning for you.

On the heads, I'd have all the valves and guides checked and a good valve job done on them. If you really want to be economical you could re-use the factory ball type rockers and studs, but if the budget could stand it one of the first things I'd do would be to upgrade to the 7/16" studs and fully adjustable roller rockers. The machinist can do that, and if you're replacing valve springs make sure you tell him what installed height you need so he can cut the spring seats, if needed.
Depending on how much work the heads need, it could be as much as $300-$400 for "everything". A lot less if all they need is the valve job.

Have them check out the crank and grind it undersize if it needs to be.

Put in a good oil pump.

Put it all back together and enjoy it. It's not going to be a 500 HP motor, but it's not going to be a slouch, either. It'll make more than enough torque on the bottom end to fry the tires for as long as you want to keep your foot in it. 

Then while you're enjoying the car, start planning for what your 400 version 2.0 is going to be and save up for parts.

You're in a good spot because you've got two 400's. That gives you the option of getting one of them going NOW, then taking your time to build the other into a monster motor.

Bear


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## jholodniuk (Nov 29, 2010)

The 4x heads I have, have new valves, springs, and seats put in. They are set up for the unleaded fuel we have now a days. Heads have never been run since rebuild. I would be better off selling them and buying some 72cc edelbrocks wouldn't I? I'd be at 9.6-9.9:1 compression. I'd have to get a bigger/better cam spec'd out. 2800 stall TC and gears will be 3.46 or 3.55 or whatever I can find. 
As for the crank its good and so are the rod bearings. Perhaps the pistons will do for this year as well. I'm not so keen on spending money on this rotating assembly when I plan on doing a stroker in the very near future. I can always use the edelbrocks later on a 461 rotating assembly I would start working on with my 71 block.


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## BearGFR (Aug 25, 2008)

If you're looking towards the future of building a stroker, I'd go with the 87 cc E-heads. On a 461 that's been zero decked and with .040 gaskets. 6 cc flat tops you'll be right at 10.3:1 which is very close to the limit for running on 93 octane with aluminum heads and a moderately aggressive cam (late intake closing event). 72 cc's would put you over 11.8:1 - way too much unless you're going to run on race gas all the time. 

You also might shop around and find someone with some 6x-4's who'd be willing to trade for your 4x's, or sell them and buy a pair outright.

If it were me, I wouldn't pop for the E-heads unless I was going to go "all the way" and buy bare castings (without valves) and have a good head porter finish them out. The valves, springs, retainers, and locks the 'ready to run' versions come with aren't what I'd want for a really strong motor so it wouldn't make sense to buy that stuff just to end up throwing it all away.

Another option would be to just put it together like it is with the heads you have. It's not going to be optimal with those huge chambers but it'll still be fun. 

If you're definitely going to build a serious motor later, then it's really up to you to decide how much you want to invest in your 'short term' 400. The good thing is that you have lots of options.


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## jholodniuk (Nov 29, 2010)

I hate to say it here, but before I bought this other 400 I wanted to put a LS motor in the car. I know everyone says don't put a chev motor in a Pontiac. I own a 2003 Silverado SS and the LQ9 in my truck is nuts for a motor with only a CAI, exhaust and custom tune. Very easy and cheap to make 600hp on the LS engines. Probably end up putting this motor back together and take it for a rip by the end of December, then I'll see how the Pontiac power feels  and likely want a Pontiac stroker!


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## BearGFR (Aug 25, 2008)

jholodniuk said:


> I hate to say it here, but before I bought this other 400 I wanted to put a LS motor in the car.


Oh man!  Go lie down on the couch and rest until that feeling passes....



Bear


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## 1968LemansGuy (Nov 21, 2010)

BearGFR said:


> Have fun - just think about what you're doing and why, and remember that the whole drive train has to be designed to work together. (A big lumpy high-rpm cam will fall flat on it's butt with a 1500 rpm stall converter)
> 
> 
> Bear


Just out of curiosity - what do you mean by this? I have a Lunati "bracketmaster" cam in a SBC 350
* Advertised Duration (Int/Exh): 300/300
* Duration @ .050 (Int/Exh): 246/246
* Gross Valve Lift (Int/Exh): .515/.515
* LSA/ICL: 108/104
* Valve Lash (Int/Exh): Hyd/Hyd
* RPM Range: 2500-6500

.030 over with dished pistons and 76cc heads. Holly 650dp in an 85 camaro, TH400. 1-1/2" shorty headers and a 3000rpm stall converter. rear gear is the stock 3.08. Thing is, when i step on it - no roast tires.. it'll bark second and runs great otherwise. a buddy mentioned he thought it was the converter, so when you said this i had to wonder. would i get more low end punch without it with this setup?

and yeah, i know this is pretty far off topic - talkin about a chevy - but i'm going for a concept thing here


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## BearGFR (Aug 25, 2008)

1968LemansGuy said:


> Just out of curiosity - what do you mean by this? I have a Lunati "bracketmaster" cam in a SBC 350
> * Advertised Duration (Int/Exh): 300/300
> * Duration @ .050 (Int/Exh): 246/246
> * Gross Valve Lift (Int/Exh): .515/.515
> ...


Well, I don't keep it a secret that I'm not a Chevy fan, but I'll do my best to give you an objective and unbiased response here.

First off, SBC's are good high rpm motors but none of them really make any torque to speak of at low rpm. That's mostly because of their geometry - that SBC 350 for example only has a 3.48" stroke, more than a quarter inch shorter than a Pontiac 400. That short stroke does two things 1) it allows these motors to "live" at higher rpm and 2) limits low rpm torque. It's simple physics really. If you're turning a crank by hand, you're going to be able to generate more twisting force on a longer crank handle than you can on a short one. Ok - nuff said on that topic. Now let's look at cam shafts and their effect on engines. An engine is basically nothing but a big air pump, so the better job it does of pumping air to fill the cylinders, the more torque (twisting force) it's going to make when that air gets mixed with fuel and burned to create pressure. Here's the thing: air, just like all matter, has mass and therefore inertia. When that intake valve opens the air column that has been stopped and sitting behind it doesn't just instantly jump up and instantly dash into the cylinder. It takes some time for it to start moving and accelerate up to speed as the downward sweeping piston creates a negative pressure (vacuum). Then just about the time the intake air flow reaches its peak velocity and is really moving into the cylinder, we slam the door (valve) and start compressing the air/fuel in the cylinder so we can light it and make some pressure. As engine rpm goes up, the "door" (intake valve) is open for shorter and shorter periods of time so if we want to really fill the cylinders as rpm goes up we have to open the valve "earlier" and keep it open longer in order to give the air column enough time to get off its butt and move into the cylinder. But here's the catch 22 - the valve opening/closing event is controlled by a direct mechanical linkage to the crank shaft. There's no way for us (modern VVT engines excluded) to vary how long the valve is open and when it opens/closes as engine rpm changes, so we have to pick a cam shaft that "optimizes" the valve timing for some rpm that we choose, and just understand that at other rpm's the valve timing is not going to be optimal. That's just the way it has to be (again, modern VVT engines excluded). With me so far?
Ok... here comes something that might seem a little surprising at first. Cam shaft choice will have very little effect, if any, on *how much* torque an engine produces. Torque comes from the combination of peak cylinder pressure after combustion and the mechanical lever effect of that pressure acting on the piston top and pushing on the rod, which has the highest mechanical advantage when the line through the long axis of the rod and the line through the center of the 'big end' of the rod to the crank centerline are at 90 degress to each other. i.e. - about halfway down the stroke length. If you've got a volume of air/fuel of X, you compress it to a volume of Y and light it, you're only going to get Z energy out of it to create pressure - regardless of how fast the engine is turning. So, peak torque is determined mostly by how much air/fuel we're burning and it's going to occur very close to the rpm where you're doing the best job of completely filling the cylinders. Cam shaft choice has little if any effect on _how much torque _an engine produces, but it has a huge effect on the rpm where that peak will occur, because it's the cam that controls the timing of the intake open/close events, and those events control when and how long the valve is open. and that's what controls how well we're filling the cylinders. 

So, what you're really doing when you put "a big cam" into an engine is you're changing the valve timing so that peak cylinder filling occurs at a higher and higher rpm. Why? Horsepower. Horsepower is actually a calculated number - it can't be directly measured. Horsepower is (Torque _times_ RPM) _divided by_ 5252. So an engine that makes 100 lb ft of torque at 2000 rpm makes twice as much horsepower as an engine that makes that same 100 lb ft of torque at 1000 rpm, even though the amount of total twisting force in both cases is exactly the same. There'a an old saying "horsepower sells cars, torque wins races". 

Ok, back to the real world and your SBC 350. What that bracketmaster cam did, how it works, is it moved your peak torque to a higher rpm. It does that by keeping the valve open longer (246/246 @ .050) and higher (.515/.515 lift) so you can get the cylinders 'full' at higher rpm. And since we know know that HP is calculated from torque and rpm, your engine now is making more horsepower (peak) because peak torque is occurring at a higher rpm than it did before.

But.... (you knew there'd be a "but", right?) There is a cost. It is possible, unfortunately, to hold that intake valve open "too long". At high rpm when the air flow is really going, we can open that intake really early, even while the exhaust is still open, because the velocity and inertia of the outflowing exhaust will actually help 'suck' the intake charge in behind it - and we need as much time as we can get to fill those cylinders. When we close the valve, the flow will continue for a brief time again because of the inertia it has - it doesn't 'stop' instantly either. At low rpm, low flow rates though, the engine is actually much worse off than it was before. We're holding that intake open much longer than needed. So long, in fact, that the flow of intake air/fuel going into the cylinder actually stops - on its -own - with the intake valve still open - because the piston has reached the bottom of the cylinder and has reversed direction, and is now pushing that intake air back out through the still open intake valve and is sucking burned exhaust gasses back into the cylinder through the exhaust valve that is also still open. (The period of time when both valves are open is call the 'overlap' period.) That 'lumpy' idle we all mentally associate with a hot car? What's really happening is the engine is stumbling and falling all over itself because it's so inefficient that the doggone thing can barely even keep running!

That's what lead to my statement about converters. If you "cam" a car for more horsepower by shifting the torque peak to a higher rpm, the motor is going to make LESS torque at lower rpm than it did before. To take advantage of the horsepower from the new cam, you have to have the car set up so that the engine can quickly get up to the rpm where the cam "comes in" and starts to run efficiently. If you put a big lumpy cam into a street car with street gears (like those 3.08's) and a street converter (1200-1500 rpm) then it's going to be a dog - because both the gearing and the converter are going to pretty much guarantee that the motor never gets anywhere close to the rpm where it would breathe well and make power. Oh, it'd be a great Bonneville car, or high speed cruiser, but it's going to take it "forever" to get up to the rpm range where it can really use the cam. On the drag strip, a stock engine with a stock cam would probably eat it alive --- but it'll sound great idling in the parking lot 

To take advantage of the cam you'd need a combination of both converter and rear gear that would allow the motor to spin "freely" up to the rpm range where the cam "comes on" almost instantly, at the hit of the throttle. There's a down side to that too --- in that a car set up that way will be quick and fast on the drag strip, and stop light to stop light, but it won't be any fun at all to drive on the highway. It's going to be over 3000, maybe 4000 rpm all the time at highway speeds which is going to make it noisy and hard to live with for more than an hour or two --- but then at that rpm that's all you'll get out of a tank of gas anwyay... 

Hope that helped...


Bear


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## 1968LemansGuy (Nov 21, 2010)

damn boy - you're good. that's was one of the best illustrated answers I've EVER gotten to ANY question. 
That car does run great at highway speeds, and when i want to pass it gets up and moves. and it does sound pretty good at a light  i did find if i HAD to spins the tires all i need to do is load it up before hittin it - but those tires cost me a good bit and i dont really want to have to buy em again.


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## jholodniuk (Nov 29, 2010)

Well.... My other 400 out of the 71 lemans was a 2 barrel intake/carb motor. I am sitting in the library at the university studying for final exams, bored, and just looked at a picture of the heads, they are code 99. Means 86cc with 1.96 and 1.66 valves. Will having higher compression but smaller valves be of benefit to me versus the 98cc and 2.11 and 1.77 valved heads I have on the running motor? I will cc them as soon as I get home on the 20th. One of the domes was kinda messed up a bit, a valve busted and cracked a piston. It might have an extra cc or two vs the other combustion chambers.


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## 66tempestGT (Nov 28, 2009)

i ran comp cams version of that cam in a 350 for a brief time and it was a dud even with more compression and rear gear. you have a bunch of middle of the road parts. compression, gear, shortys, small carb, probably a dual plane intake (just guessing). then you have one of the biggest flat tappet hydraulic cam commonly available. it would seem like a different car with a much milder cam.


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## 66tempestGT (Nov 28, 2009)

jholodniuk said:


> Well.... My other 400 out of the 71 lemans was a 2 barrel intake/carb motor. I am sitting in the library at the university studying for final exams, bored, and just looked at a picture of the heads, they are code 99. Means 86cc with 1.96 and 1.66 valves. Will having higher compression but smaller valves be of benefit to me versus the 98cc and 2.11 and 1.77 valved heads I have on the running motor? I will cc them as soon as I get home on the 20th. One of the domes was kinda messed up a bit, a valve busted and cracked a piston. It might have an extra cc or two vs the other combustion chambers.


that just promotes better flame travel


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## OrbitOrange (Jul 5, 2010)

Well Bear just blew my mind!


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## BearGFR (Aug 25, 2008)

jholodniuk said:


> Well.... My other 400 out of the 71 lemans was a 2 barrel intake/carb motor. I am sitting in the library at the university studying for final exams, bored, and just looked at a picture of the heads, they are code 99. Means 86cc with 1.96 and 1.66 valves. Will having higher compression but smaller valves be of benefit to me versus the 98cc and 2.11 and 1.77 valved heads I have on the running motor? I will cc them as soon as I get home on the 20th. One of the domes was kinda messed up a bit, a valve busted and cracked a piston. It might have an extra cc or two vs the other combustion chambers.


Changing nothing but compression really has a very small effect on torque/power output. On my 461, a full 0.5 change in compression only makes about 8 HP difference, making it really not worth pushing the limit, especially when you consider the nasty things that happen if you push it too far and get into detonation. 
You'll want to measure the chamber sizes yourself and not trust published numbers - they can and do vary enough from the published numbers to "matter". You can probably have those 99's modified to have screw-in studs and larger valves, but by the time you get all that done you'll have spent more than you would have just buying a set of 6x-4's outright. Valve size matters for air/exhaust flow, which translates directly to power, and small changes can make a big difference. Compression matters for efficient combustion/energy release, but the upper limit is determined by the quality of the fuel being used. "Rule of thumb" is around 9.3:1 max for iron heads, 10.2:1 for aluminum heads. You can "push" it some with a long duration cam/late intake closing event to reduce cylinder pressure, but you really have to stay on top of the tune-up (fuel mixture) and have a great cooling system to keep it alive for long - and too you have to ask yourself if it's worth all that for less than 10 HP?

Having said all that, I truly understand the notion of "using what you have" and making it work. The heads I'm running on my 461 "only" have 71 cc chambers. In order to get compression down to 9.46:1 I had to do some "bad" things. I had to cut more dish into the already dished pistons, I had to forego "zero decking" the block, and I had to run thick (0.075" compressed) head gaskets. In short, I've knowingly obliterated just about all the quench area in my cylinders. I did this because I *really* wanted to run those heads: they're original 1969 #722 Ram Air IV's. But I paid a price to be able to run them.

Just go into it with your eyes open. Use the various calculators that are available on the web. Don't push the 'rules of thumb' unless you're prepared to do what it takes to get away with it, and even then don't push your dynamic compression beyond 7.0 - 7.2 or your cranking cylinder pressure above 170-172.

just have fun with it and make it "yours".

Bear


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## jholodniuk (Nov 29, 2010)

Well my "69" motor is not a 69 motor. Got home yesterday for a few weeks. Looked at the numbers on the engine. 
On the front it says "YH" and 125799 just towards the passenger side of the waterpump. To the lower passenger side of the waterpump it says 24X115092.
Back of motor behind the valve cover pasenger side it says "4819 8. Looks like very likely a 73 motor?
Next question, on the 4X heads, in the middle on the intake side of the heads there is some sort of port. Actually 2 ports, one square one and if you look into it you can see a few valves. There is a smaller rectangular port just above it. Now the new gaskets I was given with this motor go around both ports. BUT... the 4 brrl intake only covers the bottom port. What are these ports for? And do I have to get a different intake to cover it? Will the Edelbrocks cover it? Performer RPM a good intake, Torker II better? My 71 motor only has the bottom square port on the 71 heads. These 4X heads are different. 

I was hoping to drop it in the car today and start it up and hear it run. Guess that will not be happening. What is the purpose of these ports? Manifold pressure?


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## jholodniuk (Nov 29, 2010)

Picture here.
IMG_4278.jpg picture by jholodniuk - Photobucket


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## BearGFR (Aug 25, 2008)

jholodniuk said:


> Well my "69" motor is not a 69 motor. Got home yesterday for a few weeks. Looked at the numbers on the engine.
> On the front it says "YH" and 125799 just towards the passenger side of the waterpump. To the lower passenger side of the waterpump it says 24X115092.
> Back of motor behind the valve cover pasenger side it says "4819 8. Looks like very likely a 73 motor?
> Next question, on the 4X heads, in the middle on the intake side of the heads there is some sort of port. Actually 2 ports, one square one and if you look into it you can see a few valves. There is a smaller rectangular port just above it. Now the new gaskets I was given with this motor go around both ports. BUT... the 4 brrl intake only covers the bottom port. What are these ports for? And do I have to get a different intake to cover it? Will the Edelbrocks cover it? Performer RPM a good intake, Torker II better? My 71 motor only has the bottom square port on the 71 heads. These 4X heads are different.
> ...


It still might be a 69. The date code is on the top rear of the block, next to the distributor hole. Look at the second photo on this web page for an example, and how to decode it.

As far as those heat riser passages in the 6X heads, there are a couple of choices: 1) find a later model QJet intake that will cover these passages or 2) block the passages off completely on both sides (even the part that the manifold covers). Some intake gaskets come with special high-heat or metallized inserts for this purpose, or you can make your own. If you don't care about having a functional choke (or if you're going to use an electric one) the "best" way is to have these passages plugged in the heads themselves with a pour of molten aluminum. It plugs the passages, reduces heat to the manifold (and intake air), and also completely separates the center exhaust ports, usually improving flow.

Bear


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