Trouble finding thin head gaskets?
10-01-2018, 02:37 PM
#1
Team Owner
Thread Starter
Trouble finding thin head gaskets?
I think that my head gasket was a Cometic MLS .021 compressed. It has to work for aluminum heads. Summit sells a .027 for a 4.030 bore. I'd even use a .015 if I could find it. What is your favorite for aluminum heads.?
https://www.summitracing.com/parts/c...make/chevrolet
https://www.summitracing.com/parts/c...make/chevrolet
10-01-2018, 03:30 PM
#2
Melting Slicks
Usually Felpro Permatorqs, but I had been looking at Cometics recently. Poke around on their site, maybe call tech support to get the right one.
http://www.cometic.com/i-24768120-gm...bore-each.html
http://www.cometic.com/i-24768120-gm...bore-each.html
10-02-2018, 06:41 AM
#5
I used GM factory 1990/1991 MLS head gaskets for my aluminum head install. No issues after 3 years of use. I've got it written down somewhere but from memory they were .028 thick.
10-02-2018, 01:05 PM
#7
Melting Slicks
The Felpro 0.015" SBC gasket is 1094.
It no longer has the black coating on it; it's now clear and EVERYTHING ON EARTH will stick to it -dust, hair, dirt -keep it in the bag until right before you install it. It's like a magnet for crap that you don't want on your head gasket.
The Felpro gasket catalog says it's appropriate for Iron or Aluminum heads.
Adam
It no longer has the black coating on it; it's now clear and EVERYTHING ON EARTH will stick to it -dust, hair, dirt -keep it in the bag until right before you install it. It's like a magnet for crap that you don't want on your head gasket.
The Felpro gasket catalog says it's appropriate for Iron or Aluminum heads.
Adam
Last edited by NewbVetteGuy; 10-02-2018 at 01:06 PM.
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gkull (10-03-2018)
10-03-2018, 02:21 PM
#9
Team Owner
Thread Starter
10-03-2018, 04:39 PM
#11
Team Owner
Thread Starter
Other than minor loss of compression, I would rather have as much gasket as possible right up to the cylinder edge.
Last edited by gkull; 10-03-2018 at 04:40 PM.
10-03-2018, 05:07 PM
#12
Melting Slicks
The problem is less material between the cylinders and water jacket. I just measured the distance between cylinders @.370 inches 4.100 - 4.030 = .070 larger than my bore. Then add another .070 from the next cylinder and you have .230 inches of gasket between cylinders. That is less than a 1/4 inch. I've had two head gasket failures on my Vette. Detonation from low octane fuel being sold out of the 93 octane super unleaded pump. I turned them into the state and testing showed that they had 87 octane in all their pumps. They got a fine! But it didn't help my vette which had a very high DCR. I had antifreeze coming out the exhaust pipe on one side. The second was my fault for not retorquing the head studs after a few heat cycles using copper head gaskets. That one blew between cylinder 3 & 5 like an inch was missing. I was racing around a track running it with my foot on the floor for the 3000 foot long main straight at the Miller race track and down towards the brake area the motor started sounding funny
Other than minor loss of compression, I would rather have as much gasket as possible right up to the cylinder edge.
Other than minor loss of compression, I would rather have as much gasket as possible right up to the cylinder edge.
http://scegaskets.com/store/chevrole...or-sbc-511961/
Adam
10-06-2018, 01:30 PM
#14
Le Mans Master
Member Since: Oct 2002
Location: Las Vegas - Just stop perpetuating myths please.
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I think a thicker gasket for sealing is more important than the benefits of quench or a little more compression. You can always use race gas on race day and keep RPM's low/below 4000 while on the street.Yes the solid copper gasket will leak a tiny amount regardless of torquing. There maybe a optimum surface roughness to use copper gaskets but I don't know what it is. I understand the benefit of copper gaskets is for reuse on race cars (mostly drag cars) that have the heads removed frequently.
10-08-2018, 11:31 AM
#15
Racer
The most important thing is quench distance. This is the distance that the piston sits down in the bore to the cylinder head. This distance should be around .039 to .040 or there abouts with the gasket in place. The less down in the bore, the thicker the gasket should be and vice versa.
10-08-2018, 12:30 PM
#16
Le Mans Master
???
The most important thing is quench distance. This is the distance that the piston sits down in the bore to the cylinder head. This distance should be around .039 to .040 or there abouts with the gasket in place. The less down in the bore, the thicker the gasket should be and vice versa.
Thanks
10-08-2018, 02:26 PM
#17
Race Director
The most important thing is quench distance. This is the distance that the piston sits down in the bore to the cylinder head. This distance should be around .039 to .040 or there abouts with the gasket in place. The less down in the bore, the thicker the gasket should be and vice versa.
A. 5+35=40 piston .005 in the hole with .035 gasket
B. 30+10=40 piston .030 in the hole with .010 gasket
The consensus seemed to be they'd rather have B, piston more in the hole with a thinner gasket.
Last edited by jim2527; 10-08-2018 at 02:27 PM.
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Vette5311 (10-08-2018)
10-08-2018, 03:12 PM
#18
Melting Slicks
Interestingly enough, FelPro says that the steel 0.015" shim gaskets CAN be used with aluminum and just leave it at that.
I noticed that Holley / MR gasket has a very similar steel shim gasket and they have a very prominent warning on them that says that they can leave imprints in aluminum heads.
Here's the warning from Holley / Mr Gasket: "Steel Shim Gaskets are not recommended for use w/ aluminum cylinder heads since the endorsements in the gasket will cause indents in the deck surface of the heads."
Adam
I noticed that Holley / MR gasket has a very similar steel shim gasket and they have a very prominent warning on them that says that they can leave imprints in aluminum heads.
Here's the warning from Holley / Mr Gasket: "Steel Shim Gaskets are not recommended for use w/ aluminum cylinder heads since the endorsements in the gasket will cause indents in the deck surface of the heads."
Adam
10-08-2018, 03:16 PM
#19
Melting Slicks
More doesn't propagate flame travel as well and less doesn't leave enough room for proper clearances. There was a good discussion on Speedtalk. 40 isn't always 40. Using simple math as an analogy which is better, A or B when the second number is gasket thickness?
A. 5+35=40 piston .005 in the hole with .035 gasket
B. 30+10=40 piston .030 in the hole with .010 gasket
The consensus seemed to be they'd rather have B, piston more in the hole with a thinner gasket.
A. 5+35=40 piston .005 in the hole with .035 gasket
B. 30+10=40 piston .030 in the hole with .010 gasket
The consensus seemed to be they'd rather have B, piston more in the hole with a thinner gasket.
Vizard had a good rule-of-thumb on how much power increase you get from a decreasing quench (assuming due to a faster burn); but I didn't save it....
If I remember right the "ideal" / "safe" piston to head clearance is also based upon the rod and rod bolt that you have and the RPM that you plan to spin, right? (Lower RPM with less stretchable rod materials / designs can safely have tighter piston to head clearances)
Adam