Head Gasket for a piston .003 out the top?

[Jeepinscott]

Which head gasket should I use with a piston sticking out .003? This is a non-stroker 4.0 with balanced everything and kb pistons, chevy valve springs, roller rockers et all. It will live it's life at high RPM's and I want to run 91 octane gas. The static compression ratio calculates to 9.97.

[SilverXJ]

What quench are you looking for? The New Mopar performance is actually .044" thick, so using that you would have a quench of .041".. other gaskets are .051".

You went with the KB944 forged pistons and didn't throw in a 258 crank?

[Jeepinscott]

I have read that .41 would work and is close to ideal, but what about valve clearance?

[RAPTORFAN85]

Valve clearance will almost never be a problem on a jeep 4.0 unless you have a piston way out of the block, heavily plained head, huge lift cam, and very thin head gasket.

[PolloLoco]

Valve clearance will almost never be a problem on a jeep 4.0 unless you have a piston way out of the block, heavily plained head, huge lift cam, and very thin head gasket.

How heavily of a planed head and how much valve lift would be huge, more than 0.50" lift?

[RAPTORFAN85]

Valve clearance will almost never be a problem on a jeep 4.0 unless you have a piston way out of the block, heavily plained head, huge lift cam, and very thin head gasket.

How heavily of a planed head and how much valve lift would be huge, more than 0.50" lift?

With my setup (zero deck, .010 plained head, .040 gasket and .475 lift) there was almost a full 1/4" of clearance, so .250 clearance left to play with. You can use any combo of head plaining, valve lift or decking of the block and add them together to reach the .250 clearance that is left.

[PolloLoco]

With my setup (zero deck, .010 plained head, .040 gasket and .475 lift) there was almost a full 1/4" of clearance, so .250 clearance left to play with. You can use any combo of head plaining, valve lift or decking of the block and add them together to reach the .250 clearance that is left.

Is that .250" to the top of the piston or are you taking into account piston dish volume?

According to this site the 68-201-4 cam from your signature has a 0.447" lift.

[RAPTORFAN85]

Thats with the piston dish. I have .475 lift because I have 1.7 roller rockers.

[PolloLoco]

Thats with the piston dish. I have .475 lift because I have 1.7 roller rockers.

It looks like I'm going to have to go do some reading because I don't know what that means.

Did I mention that this project is a learning experience for me? I have seen the innards of an engine before but I just haven't done it myself.

[RAPTORFAN85]

stock rocker arms are 1.6 ratio. Mine are 1.7 ratio.
stock lift is .447 so if you divide by the stock ratio of 1.6 you get .279, which is lift at the cam.
Multiply .279 by the new rocker ratio of 1.7 and you get .475, thats your new lift at the valve.

[PolloLoco]

stock rocker arms are 1.6 ratio. Mine are 1.7 ratio.
stock lift is .447 so if you divide by the stock ratio of 1.6 you get .279, which is lift at the cam.
Multiply .279 by the new rocker ratio of 1.7 and you get .475, thats your new lift at the valve.

http://www.compcams.com/Technical/Catal ... /20-25.asp
The Valve Lift column states "W/1.6 ROCKER," now I'm tracking.

How deep is the bottom of the dish on your pistons?