Increase 3500 compression without changing pistons

[3400beretta]

How much can the compression be increased without changing pistons? I've been reading for quite some time, and I can't seem to find exactly what I want to know. Can 0.040" gaskets be used? Are they available in a 3.8" bore without getting into something custom? Or is there not enough piston to head clearance? I tried using the CR calc, but I can't for the life of me find an exact number for the dish volume of the 3500 piston. But from what I could see, if the heads could be milled 0.020", and a 0.040" headgasket used, it should bump the compression up to about 10.8 correct? And then what about piston to valve clearance?

[Superdave]

Yes you can shave the heads .020 to gain a little SCR but you will lose .020" of clearance to the pistons
No, you cannot use .040 gaskets
3500 pistons pop out right about .020"
Piston to valve clearance shouldn't be a problem unless you are running a large cam.

search for posts made by me for some carnage pics of piston to valve clearance problems.

[ForcedFirebird]

Yes you can shave the heads .020 to gain a little SCR but you will lose .020" of clearance to the pistons
No, you cannot use .040 gaskets
3500 pistons pop out right about .020"
Piston to valve clearance shouldn't be a problem unless you are running a large cam.

search for posts made by me for some carnage pics of piston to valve clearance problems.

I can't agree more. When I measure the 3.4 pistons (.0095") I could hardly believe that GM had a .0305" quench - guess it didn't matter when the engine died at 5500RPM, lol.

[3400beretta]

So, would it be possible then, to shave 0.020" off the pistons, and then use a 0.040" gasket?

[MidnightriderZ24]

Yes you can shave the heads .020 to gain a little SCR but you will lose .020" of clearance to the pistons
No, you cannot use .040 gaskets
3500 pistons pop out right about .020"
Piston to valve clearance shouldn't be a problem unless you are running a large cam.

search for posts made by me for some carnage pics of piston to valve clearance problems.

didnt the valves hit the pistons cuz of the rod seeing 7k alot?

[bszopi]

You aren't going to see an increase in compression (well, maybe a fraction of a percent) if you shave the pistons just to use a thinner gasket. The only increase you will see is from a now very slightly smaller piston dish volume.

[ForcedFirebird]

didnt the valves hit the pistons cuz of the rod seeing 7k alot?

Don't forget the 238* duration on the cam

I'm trying 236* and have more clearance with .0095" pistons/.060" gaskets.

[Superdave]

dunno.. but this year i'll be running .060 gaskets with my pre-clearanced pistons and hopefully a nice double roller timing set.

[SappySE107]

I just wanted to say, that shaving the heads .020 doesn't give you less clearance between the piston and head. its the valve clearance, which really shouldn't be a problem.

Swap to 3400 heads if you want compression.

[Superdave]

I just wanted to say, that shaving the heads .020 doesn't give you less clearance between the piston and head. its the valve clearance, which really shouldn't be a problem.

Swap to 3400 heads if you want compression.

That's what i ment..

Damn you Captn Morgan!