Compression too high?

[Dragonfly]

You were asking about using two Felpro gaskets with the Felpro cooper shim in-between, well that is exactly what I have on mine. As mentioned in one of the other replies you are going to have to take a close look at your timing chain, what you will find which is what happened to me is that the timing chain is a little to short. What I did to remedy that problem was to insure that no shims were being used and to use my old chain guides and tensioner because they were worn enough to allow the chain to just fit. Here is the info on my engine.

 

cam: 270/270 .46 lift

 

head: P90 shaved till each chamber measured 50cc's

 

block: F54 de-burred, casting flash removed, all edges radiused

 

pistons: Arias forged flat tops, 356 grams each, full floating

 

rods: L24, race prepped, shot peened, balanced

 

Crank: LD28, wet magged, polished, balanced

 

Compression: 9.7:1 (run 89 octane California gas)

 

Timing: 18 deg. at idle, 35 deg. mechanical, all in by 2500 rpm's (no vacuum advance, phase manualy set and locked in place)

 

Head gasket(s): Felpro, cooper shim, Felpro **** NOTE**** if you are over-bored (like mine) spend ALL the time needed to get those gaskets lined up perferct around the bores because the gaskets are not made with the best of tolerances and if your piston even lightly touches the gasket you will be pulling it apart and replacing it reeeeaaaal soon (experiance speaking).

 

I have been running it like this for 3 years now (after replacing the head gaskets that were touching #5 piston) and I have not had any problems with it. I race this car on a regular basis and I drive it on the streets often enough to say it has been quite reliable. I agree with those before me that you are going to be hating it if you run anything higher than 10.5:1 compression, and IMHO if you would like to drive it just a little more often try to lower the compression to somewhere between 9.5:1 and 10:1.

 

Dragonfly

[burntz]

Dragonfly,

 

Thanks, this was the advice I was looking for. I've decided to do the felpro sandwich to lower the compression to about 9.5:1 the head has been shaved on the top and bottom so hopefully I won't have a cam chain issue. If I knew what the original thickness of the head was then I could measure and do some math to know for sure. I'll probably end up driving this car more than planned so I might be happier with the lower compression.

[Guest norm[T12SDSUD]]

I would suggest NOT using the Fel Pro's with the shim. If your alignment is off at all it will blow on you. Mine only lasted three weeks. The Fel Pro has a very narrow sealing ring around the combustion chambers.

I've had great success with using two Victor Reiinz headgaskets, available from NAPA and then coating both sides in Copper Sealant. This has worked great with no water leaking issues at all as well.

 

 

Norm

[JMortensen]

Dragonfly' date='

 

Thanks, this was the advice I was looking for. I've decided to do the felpro sandwich to lower the compression to about 9.5:1 the head has been shaved on the top and bottom so hopefully I won't have a cam chain issue. If I knew what the original thickness of the head was then I could measure and do some math to know for sure. I'll probably end up driving this car more than planned so I might be happier with the lower compression.[/quote']

I am pretty sure the stock thickness of any L6 head is 4.250". A machinist would be able to look it up in 2 seconds. Why was the head milled on the top? Warped?

[Guest norm[T12SDSUD]]

BTW, the Copper Sealant that I use is from a spray can and not from a tube in case you were wondering.

 

Norm

[Tony D]

would that be akin to "RTV" on your head gasket, "BubbleNorm"? LOL

 

;^P

[Guest norm[T12SDSUD]]

That's cold TonyD!! No, that Copper Spray works excellent and prevents water leaks between the gaskets.