3.4L iron headgasket on a 3400

[95Grand-Am]

I put 3.4L camaro head gaskets on my 3400 to raise the compression. But, I was recently told that this might be risky because of pistion to head clearance will be closer than recomended. I'm running a stock cam and my rpms will never be over 6000rpms. The pistions I mesured to be .012" over the top of the block and the head gaskets are .040" thick giving me .028" clearance. Has anyone else tried this and did you have problems. What do you guys think should I change them back to stock or will they be ok? This engine has to last about 600 1/3mile laps.

[Superdave]

use 3400 gaskets, you'll bend valves if you don't.

[95Grand-Am]

Thanks Superdave, but I thought you said your valves would have touched anyway just not as much. I should have a lot more piston to valve clearane than your engine because I don't have nearly he lift or duration, and when you advance a cam doesn't it make the exhaust valves run closer to the pistons. I would like to talk more about this, I have a couple of months before I need to do anything and would like to hear all point of view before taking the engine apart again.

[ForcedFirebird]

Your better off milling the heads, it's a lot cheaper than breaking parts.

If the heads don't need remanufacturing, the shaving alone won't be much.

[Superdave]

Thanks Superdave, but I thought you said your valves would have touched anyway just not as much. I should have a lot more piston to valve clearane than your engine because I don't have nearly he lift or duration, and when you advance a cam doesn't it make the exhaust valves run closer to the pistons. I would like to talk more about this, I have a couple of months before I need to do anything and would like to hear all point of view before taking the engine apart again.

it's not the piston to valve clearance that will get you, it's the piston to head clearance that'll eventually cause problems.. the 3400 pistons pop up .020, that leaves you with the thickness of a business card between the head and piston. Rods stretch at higher RPM.

As it sits, i'm very lucky that i didn't blow my engine last year. I did some damage that's costing me a few hundred bucks to fix though.

My problem was that i didn't measure the popup of the pistons myself, i just went off what was posted and assumed i'd be ok. After seeing .034" deep dents in my pistons i'll never trust posted measurements again. If you measured .012" popup and you are confident that number is dead accurate then by all means risk it.. lol

with a 3400 you have quite a few different piston choices that could easially net you some serious compression in a much safer manner.

[95Grand-Am]

Because the combustion chambers are so small you would have to mill alot of material off for it to make much differance. Where did .02" pop up come from, is there that much variation between blocks? I put .02" pop up in the CR calculator with every other value stock and it comes out to 10.17. Has anyone run 3.4L camaro head gaskets on a 3400 and had a piston to head collision?

[Superdave]

the CR calculator is wrong, i'm guessing the numbers were fudged to come up with the propper SCR for a stock engine.

Bore 3.622"
Stroke 3.307"
Head Gasket Bore 3.75"
Head Gasket Compressed Thickness .060"
Combustion Chamber Volume 26.4cc
Piston Dome Volume 31.75cc
Piston Deck Clearance -.020"
Final Displacement 3349 cc
Calculated Compression Ratio 9.5:1

Those should be the propper numbers.


I'm gathering all the stuff to CC heads and pistons, hoping to have some actual numbers soon...