Can I put a cometic .36 or .30 gasket on my stock ls6 engine. I want to raise my compression to like 11.1 or 11.3. I know I can do it shaving the heads but can i do it with the gaskets only?

 

I was wondering the same, I'm trying to have a nice running motor without pulling the heads.

 

Yeah. Im triying to do it. Hope someone give info.

 

Patrik g? Chris1313? Or anyone please ?

 

Why wouldn't you be able to?! The motor will have a tighter quench which will produce more power/torque.

 

No, the pistons usually stick out the hole .005-.010

Using a .030 or .036 gasket will give you too tight of a quench.

For example a .036 gasket minus .007 piston out of the hole and you get .029 quench

You want .035-.045 quench, which is recommended by most builders

 

But technically can I use it. If the valves do not touch the pistons. I want 11.1 or more cc.

 

I would be very worried about the rod stretch at TDC once the engine warms up and smacks the head with the piston.

 

Quench is about piston to head contact not PTV contact. Things change size with temperature, pistons rock in the bore, there is rod bearing to crank journal clearance the rod can move around some with. Point being that just because measuring everything cold on the stand static shows the piston wont hit the head doesn't mean it will all still clear running.

Basically bare minimum I have ever heard of on a street SBC of any sort was about .030 with most considering .035 to be a bit safer.

If you really think everyone is wrong though feel welcome to enlighten us with your experiment, just understand that the reason we want this much clearance is because of how everything moves/stretches/expands/rocks in operation and that letting the piston contract the head would likely do damage.

 

ok thanks. I dont know it was the pistón.

 

i dont think everyone is wrong.if that was the case i would done it and would not has post this question. It was Just that is other post one Guy was runnin a .36 gasket and was running good. I am not saying you are wrong i only want opinions on this.

 

How much cc would a .40 gasket do? Do they make something betwen .40 and .36?

 

Where are the pistons sitting now? As has been said on these motors they are usually above the deck a little. HAVE TO know that before you can go ordering a gasket under say .050. I just say .050 because the pistons are unlikely to stick out enough to cause too tight a quench with a gasket that thick, but it is possible you could be on the ragged edge of unsafe if you ordered a .040 and the piston happens to be .01 up. If it happens to be up .005 then a .040 gasket would be great.

 

i have to look that. I will change the heads and can. Putting tea ls6 and ecs Na cam

 

it cost like 80$ to mill the heads. you can use factory pushrods to some extent

 

mill the heads as said above DO NOT run under .035 quench on a stock bottom end ls motor.....with a good set of steel rods you can get away with .030~ if you are careful

 

arent the Factory rods powered forged Steel?

 

I don't want to hijack the thread but does someone know how much you can mill the head before it cause intake port misalignment problem?I assume you need to mill the intake too like the old sbc.

 

i think you can mill them about 58cc or 59cc. Since the manifold is not touching in the bottom like the Old sbc

 

A .030" or .036" gasket on a stock bottom end is not a smart move due to piston to head clearance issues.

A .040" gasket would be as close as I would go.

And you can mill the stock heads .040"-.045" before you start to have some alignment issues. .030" is plenty however.