kawi600

I installed a hamilton cam in my truck and got a little too excited with it and popped the head gasket a couple days after.
So I had my local diesel shop install studs and o-rings. They used some sealant in the coolant system thats probably some sort of silicate. They also shaved .015 off and installed a .020 gasket. So the squish was changed by .005. Doesnt seem like a whole lot, but it feels like I lost a bunch of low end power.
I need a bit more throttle than before and the rpms climb rapidly till 1800 when the turbo starts to light. Cranking up the AFC yields moderate results with a lot more pre-boost smoke =(
Anyone have a similar situation and what did you do to correct it?

Tate

They took .015 off the head? If so, then you lost a full point of compression with the .020 gasket, down to 15.3:1. The only reason for the thicker head gasket when decking the head would be for valve to piston clearance, and there are better ways than putting in a thicker head gasket.

Brokenarrow

I have the thicker head gasket and i have fly cut pistons, my compression ratio is around 14;1 and if i lay into it before 2000 RPM its just a smoke show, more of a grayish white smoke.

Mike Holmen

The cylinder head combustion chamber is pretty much flat. Most of the combustion occurs in the piston. 0.015in off the head, thats tons of material.
I'm with Tate, is that you drop the compression ratio by a point.
I would hazard a guess at that you could run a stock gasket with that much material gone.

kawi600

If I ran a stock gasket it would bump compression up and possibly cause problems with piston / valve clearance at high rpm even with the springs.
Maybe if I pop it again in the future Ill have the amount matched to the gasket.
I think Im going to crank the timing up a bit to see if that helps.

wcbcruzer

So if they need to take that much material off the head, what other ways are there of putting it back together while keeping the stock 17.5:1 compression?

kawi600

The only way would be to shave off .020 and use the .020 gasket. unless you had a lot of money to burn on modding the pistons or block.

I think bumping the IP timing up will help with the smoke and power problems. What do you guys think? I had it put down to 17 when I did the cam but now I think I need to go up a bit more.

Tate

Taking material off the head will not affect compression ratio, as it is flat to begin with. The clearance volume is in the piston, unlike a gasser, which is in the head.

Reason for the thicker head gaskets is when you deck the block, to keep piston to head clearance with in spec. Since you decked the head, piston to head clearance was fine from the start.

To get piston to valve clearance back, they can lap the valves deeper in the seats to get the right reccesion. Would have been better to actually check valve/piston clearance before bolting the head down to see how much interference (if any) exist.