Proper head gasket
Thread Starter
Drifting
Joined: Dec 2012
Posts: 1,504
Likes: 73
From: Georgetown TX
I don't doubt that you know what you are saying, and I really appreciate your advise, but I am just trying to understand all of this. If the original engine spec was .021 and I am now putting on a gasket that is .051 thick, isn't that going to hurt my compression ratio, thus lowering my performance. 89's can't afford to lose any performance
Melting Slicks
Joined: Nov 2010
Posts: 2,216
Likes: 113
From: Michigan
Depending on how much you milled the heads it could be more comp than was stock slightly or close with a thicker gasket. Then you have to consider the piston to valve clearance depending on your cam with milled heads and a thin gasket.
Thread Starter
Drifting
Joined: Dec 2012
Posts: 1,504
Likes: 73
From: Georgetown TX
Ok, that makes sense, but what if your heads don't need to be milled, and everything is bone stock? Would I go with thinner gasket. I don't know what the difference in cr will be between the two .021 and .051
Team Owner
Joined: Sep 2003
Posts: 25,394
Likes: 2,741
I really believe that the .021 is for "tin/sheet-metal" gasket for a cast-iron head L98 '85- '86. There were thin gaskets done that are coated on both sides for aluminum heads but I didn't bother to look and confirm them. I'd think they're the gaskets mentioned by "Churchkey".
Thread Starter
Drifting
Joined: Dec 2012
Posts: 1,504
Likes: 73
From: Georgetown TX
I really believe that the .021 is for "tin/sheet-metal" gasket for a cast-iron head L98 '85- '86. There were thin gaskets done that are coated on both sides for aluminum heads but I didn't bother to look and confirm them. I'd think they're the gaskets mentioned by "Churchkey".
58cc heads. I think this is standard
4.0 bore
3.48 stroke
.025 piston to deck height I think this standard
I don't know piston dome cc. Anyone know what number to use. I think it might be +12 from some reading I've done
Last edited by mlm0; May 7, 2016 at 11:01 PM.
Melting Slicks
Joined: Sep 2008
Posts: 2,376
Likes: 111
From: Cherokee National Forest TN
Stock compression for your engine is 9.5 to 1.
Stock pistons are flat tops & should have 4 small valve recesses each probably a total of + 4 cc's.
No need to worry about valve events it is only required when figuring dynamic compression ratio. Your concern is static compression ratio.
Agree with WVZR-1 the .021 thick gasket is not for your application.
Quick figures on my part indicate your compression ratio with the new gaskets will mimic stock compression.
Mic the removed head gasket & comp it to the new gaskets. If there is a difference get gaskets that match the removed units.
All of this conversation is speculation at this point take it apart to see what you need.
Stock pistons are flat tops & should have 4 small valve recesses each probably a total of + 4 cc's.
No need to worry about valve events it is only required when figuring dynamic compression ratio. Your concern is static compression ratio.
Agree with WVZR-1 the .021 thick gasket is not for your application.
Quick figures on my part indicate your compression ratio with the new gaskets will mimic stock compression.
Mic the removed head gasket & comp it to the new gaskets. If there is a difference get gaskets that match the removed units.
All of this conversation is speculation at this point take it apart to see what you need.
Thread Starter
Drifting
Joined: Dec 2012
Posts: 1,504
Likes: 73
From: Georgetown TX
[QUOTE=Churchkey;1592167846]Stock compression for your engine is 9.5 to 1.
Stock pistons are flat tops & should have 4 small valve recesses each probably a total of + 4 cc's.
No need to worry about valve events it is only required when figuring dynamic compression ratio. Your concern is static compression ratio.
Agree with WVZR-1 the .021 thick gasket is not for your application.
Quick figures on my part indicate your compression ratio with the new gaskets will mimic stock compression.
Mic the removed head gasket & comp it to the new gaskets. If there is a difference get gaskets that match the removed units.
All of this conversation is speculation at this point take it apart to see what you need.[/QUOTE
Alrighty then, .051 it will be
Thanks guys Just remember, it's not that I doubt the info I'm given, I just want to understand everything I can. When I got into guns, I learned gunsmithing, when I got into golf, l learned how to make and repair golf clubs, so on and on. Must have some type of ocd
Stock pistons are flat tops & should have 4 small valve recesses each probably a total of + 4 cc's.
No need to worry about valve events it is only required when figuring dynamic compression ratio. Your concern is static compression ratio.
Agree with WVZR-1 the .021 thick gasket is not for your application.
Quick figures on my part indicate your compression ratio with the new gaskets will mimic stock compression.
Mic the removed head gasket & comp it to the new gaskets. If there is a difference get gaskets that match the removed units.
All of this conversation is speculation at this point take it apart to see what you need.[/QUOTE
Alrighty then, .051 it will be
Thanks guys Just remember, it's not that I doubt the info I'm given, I just want to understand everything I can. When I got into guns, I learned gunsmithing, when I got into golf, l learned how to make and repair golf clubs, so on and on. Must have some type of ocd
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