Final head gasket selection, WWC4 Tech do?
Thread Starter
Large Impressive Member
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From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Final head gasket selection, WWC4 Tech do?
With an initial great idea from a fellow forum member, I built this engine with and for a tight quench area to achieve superior combustion efficiency. Using a 3.80" stroke crank with pistons for a 3.75" stroke, it brought the pistons to just .002" from deck height, virtually zero decked w/o decking the block. Now here's my dilemma. The practical safe limit for quench area is generally considered to be around .040" to allow for any piston rock, etc. Some think that I can exceed this and squeeze it tighter with no problems because the pistons are fitted at .0025" and so rock will be minimal compared to a full race engine where the pistons would be more loosely fitted. Long story short (too late for that, I know) should I continue to use the Impala gasket which crushes to .029" and which would give me a quench area of .032"? Or should I play it safe and use the Felpro (.039" crushed) for a final quench area of .042"? BTW and FWIW, piston to valve clearance is more than adequate either way and the SCR difference is only .2 between the two gaskets, so that's not a factor I consider of any importance compared to the benefits of maximizing quench.
Le Mans Master
Joined: Apr 2000
Posts: 6,341
Likes: 1
From: Shelton CT
Originally Posted by vetteman9368
Cometic, damn near any thickness you want, and reuseable
I used one on my '85 when swapping on race heads, then swapped back the stock ones a years later for the supercharger, and reused the cometic gaskets I used before.. Worked perfectly until the end.I used .0052 for the L98, and have a new set (.0028) ready for my LT1, should I chose to go nuts and do a heads/cam swap again..
Le Mans Master
Joined: Jan 2003
Posts: 8,596
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From: Portland Oregon
The only concern with using Cometic or any MLS style gasket is that block and head surface preparation has to done correctly. If a machine shop uses a cutter that is the old stone type surface machine your gaskets will leak. A CBN type cutter is the best way to assure a leak proof seal. I found out the hard way! Your final quench of .042 using the .039 gasket would be perfect! Not only should you be concerned about VP clearance or piston rock but you should also be concerned about rod growth and piston expansion. It is minimal with steel rods so in your case there is nothing to worry about. But in a all out race engine with aluminum rods it is a concern.
Race Director
Joined: Sep 2000
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From: The Top of Utah
That is a tough decision. The benefits of a quench area decrease as the distance increases, and is pretty well non-existent at more than .060" piston to head clearance. You cannot go wrong with the .039" Fel-Pro gaskets. My Chevrolet Power Book recommends a piston to head clearance of .035" minimum, with a piston clearance as high as .005". With your fairly tight pistons and a difference of only .003", from the minimum spec, I don't think I could pass up the opportunity of a really superior quench area by using the Impala gaskets.
RACE ON!!!
RACE ON!!!
Thread Starter
Large Impressive Member
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From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Originally Posted by CFI-EFI
That is a tough decision. The benefits of a quench area decrease as the distance increases, and is pretty well non-existent at more than .060" piston to head clearance. You cannot go wrong with the .039" Fel-Pro gaskets. My Chevrolet Power Book recommends a piston to head clearance of .035" minimum, with a piston clearance as high as .005". With your fairly tight pistons and a difference of only .003", from the minimum spec, I don't think I could pass up the opportunity of a really superior quench area by using the Impala gaskets.
RACE ON!!!
RACE ON!!!
But I'm still glad you checked in. I found an SCE gasket which is copper and has an .032" compressed thickness. But I think this would require the use of O-ring grooves, not an option at this point with the block assembled. I also found a Flatout Racing Gasket that is rubber coated copper and is .031" compressed. Would the rubber coating negate the need for O-ring grooves in a NA engine of roughly 11.1 SCR? The bad thing is that it seems I'd be looking at an approximate 3 week wait on them. Thanks for all responses thus far. I know, I think too much sometimes. (And not enough other times.....) 
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Race Director
Joined: Feb 1999
Posts: 12,772
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From: Indianapolis IN
I just took off a Cometic .027" thick and it sealed fine for 8K miles, it is in good shape except some of the silicone came off in a spot or two,
but honestly, I will go to an marine gasket .039" on this next install. re-torquing is no fun, and the camps are split 50-50 on retorquing, some say to do it and some say it is not necessary, I would put them back on if re-torquing was not required.
Kid, did you or have you retorqued your non stock thickness head gaskets? Cometic says "no re-torquing reqd
but honestly, I will go to an marine gasket .039" on this next install. re-torquing is no fun, and the camps are split 50-50 on retorquing, some say to do it and some say it is not necessary, I would put them back on if re-torquing was not required.
Kid, did you or have you retorqued your non stock thickness head gaskets? Cometic says "no re-torquing reqd
Last edited by LD85; Jun 8, 2006 at 02:16 PM.
Melting Slicks
Joined: Oct 2002
Posts: 3,193
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From: Cincinnati Oh
Originally Posted by CFI-EFI
That is a tough decision. The benefits of a quench area decrease as the distance increases, and is pretty well non-existent at more than .060" piston to head clearance. You cannot go wrong with the .039" Fel-Pro gaskets. My Chevrolet Power Book recommends a piston to head clearance of .035" minimum, with a piston clearance as high as .005". With your fairly tight pistons and a difference of only .003", from the minimum spec, I don't think I could pass up the opportunity of a really superior quench area by using the Impala gaskets.
RACE ON!!!
RACE ON!!!
I was looking for CFI's post too.
I'm sure you've manually checked the V/P clearance with clay, etc? I'd go with more quench than less, given your situation. It should be a rockin' motor.
Thread Starter
Large Impressive Member
Joined: Jul 2003
Posts: 65,811
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From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Originally Posted by CFI-EFI
Sorry, I have no knowledge of the rubber coated copper gaskets. You could have the block decked .007".
RACE ON!!!
RACE ON!!!
Originally Posted by LD85
Kid, did you or have you retorqued your non stock thickness head gaskets? Cometic says "no re-torquing reqd
Originally Posted by Ramanstud
I was looking for CFI's post too.
I'm sure you've manually checked the V/P clearance with clay, etc? I'd go with more quench than less, given your situation. It should be a rockin' motor.