G5x3 & Cometic 0.040 Head Gaskets
G5x3 & Cometic 0.040 Head Gaskets I'm thinking about doing the Cometic 0.040 Head Gaskets when i do the g5x3 install and LT headers.
I have done a search.. still can't figure out what that would bump the compression ratio to?
would it be safe? shouldn't affect Piston to valve cleareance right?
this is for a 2001 z06 .. thanks!
I have done a search.. still can't figure out what that would bump the compression ratio to?
would it be safe? shouldn't affect Piston to valve cleareance right?
this is for a 2001 z06 .. thanks!
The 2001 LS6 MLS gaskets are rated at .060" crushed thickness. So it would in effect amount to milling the heads ~.020". That comes to around -3.67cc's. On stock LS6 heads I would think around 10.9:1 to 11:1 A potential problem may exist though. Most LS6's have the pistons out of the hole ~.008" and this would reduce you quench to .032". This is tighter than most recommendations which is .035"-.040". It would be best to pull the heads, measure your deck clearance and purchase the correct gasket when the deck height is known. The question as to whether this would affect piston to valve clearance can be answered as a yes it will. Whether it will put p/v too close you will probably have to measure. The G5X3 cam fits stock setups when run at a 114lsa, but the 112lsa version is too close. At least that is what I have read. You may be able degree the cam to get it to fit, but you may also retard the cam out of some of it's power. You MAY want to look at the Cometic .045" gasket as that will still bump your compression and keep your quench distance within limits.
cool i'd do the the safer one then.. .045" that should still bump it to what 10.5:1 compression?
i don't want to have the heads pulled yet.. just gonna get the cam and headers put on.. do heads later. i figured while i'm getting the headers put on.. might as well bump the compression a little worth maybe what 5/10rwhp more?
i don't want to have the heads pulled yet.. just gonna get the cam and headers put on.. do heads later. i figured while i'm getting the headers put on.. might as well bump the compression a little worth maybe what 5/10rwhp more?
Originally Posted by Insomniak
cool i'd do the the safer one then.. .045" that should still bump it to what 10.5:1 compression?
i don't want to have the heads pulled yet.. just gonna get the cam and headers put on.. do heads later. i figured while i'm getting the headers put on.. might as well bump the compression a little worth maybe what 5/10rwhp more?
i don't want to have the heads pulled yet.. just gonna get the cam and headers put on.. do heads later. i figured while i'm getting the headers put on.. might as well bump the compression a little worth maybe what 5/10rwhp more?
Originally Posted by Insomniak
thanks man.. very informative. i appreciate it! 
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Verdad Gallardo ok so .. if its safe to assume.. .085" intake clearance w/ the G5x3 and .045" gaskets reduce that to .070" intake clearance.. how much clearance is considered safe?
Originally Posted by DanZ28
Don't have anything to add, but this is informative. What's the formula for figuring you CR and the quench area?
Give it some time, more people will chime in.
I think .075-.080" is considered minimum clearance. If you float a valve just once, in your in for some major repair if you don't have proper clearance.
I to am trying to figure out my exact CR and Quench. Not to steal the thread, but how would you calculculte this:
.005 off the deck...Flat top pistons +.008 (below deck) with -2cc releifs...3.905 bore...heads milled .035"...Cometic .040" gasket...Did I miss anything? I'll do more research as well.
Thanks,
Dan
I think .075-.080" is considered minimum clearance. If you float a valve just once, in your in for some major repair if you don't have proper clearance.
I to am trying to figure out my exact CR and Quench. Not to steal the thread, but how would you calculculte this:
.005 off the deck...Flat top pistons +.008 (below deck) with -2cc releifs...3.905 bore...heads milled .035"...Cometic .040" gasket...Did I miss anything? I'll do more research as well.
Thanks,
Dan
To answer my own question, looks like I'm approximately 10.75 CR and a .048"quench. I think I screwed myself with a .040 gasket, should of went .030" to get a .038" quench
Dan
Dan
Last edited by DanZ28; Dec 10, 2004 at 02:31 PM.
BTW, by my calcultion, you would be 11.0 CR with a .040 gasket and 10.88 CR with a .045" gasket. Like was stated above, you probably wouldn't want to go thinner than a .045" gasket to keep your quench down to a .037".
Damn amazing what info you can find on this site sometimes
Thanks,
Dan
Damn amazing what info you can find on this site sometimes
Thanks,
Dan
Originally Posted by Insomniak
ok so .. if its safe to assume.. .085" intake clearance w/ the G5x3 and .045" gaskets reduce that to .070" intake clearance.. how much clearance is considered safe?
The safe clearance has to do with the valves, the pistons, the connecting rods, and how fast you plan on spinning the motor. For a stock bottom end LS6 with stock valves and running to ~6800-7000rpm I have read minimum is .080" on the intake and .100" on the exhaust.
