i spoke to the GM parts department today about head gasket number 10105117 which is supposed to be compressed thickness of .028 as found in multiple thread on here, and he told me that the part number i gave him is the original part, and not a thinner gasket, i thought the stock thickness was .039. i am replacing the headgaskets, so im going to put a little bit thinner gasket on there just for a little bit more power. so i figured going from .039 to .028 would be my best bet. but i dont know what to do now that he told me that this gasket is the stock replacement. he also said his performance book does not list a thinner gasket except for a steel shim gasket and .015 or something around that size, but i dont think i want to go that thin.

 

He's and idiot talk to somebody else. 117 Small block composition with SS faces .028" compressed.

 

What quench height are you going for?

 

im not going for any specific quench hieight, i just wanted to put a thinner head gasket on it to boost compression ratio a little bit. it is a stock L98 5.7L block with original heads and cam. im going to clean the heads off really good in my heated solvent tank, and put them back on with a thinner gasket. what is the stock thickness of the original head gasket? if the 10105117 is not the O.E. replacement gasket, does anyone have the part number for the O.E. gasket?

 

Hmmm...
if you're not sure what the quench is, I wouldn't play w/ head gasket thickness...the compression ration increase and power gained from it would never be noticed...

In short, you won't gain ANY power in doing it...and you invite other troubles. It's not like the factory tolerances on these engines were close....I've seen BIG differences on the same type / year engines...


HTH

 

GM has no clue what thickness their head gaskets are.

Now that we've got that out of our system, if GM says it's .028" compressed, then it's a pretty safe bet it's .028" compressed.

But that's a "replacement" gasket; not the OE gasket. The only way to know what it will do to your CR, is to measure the OE gasket when you take it apart.

Odds are, even if you had the part # for the OE one, you couldn't buy it over the counter. Factory parts are like that alot of the time. The service part isn't the same as the OE one.

 

www.paceperformance.com

I don't know what one is stock here a couple.

10185054 .051" ZZ4 head gasket

10159455 .039" composition

10185054 .041" heavy duty

 

by having a thinner head gasket, it tightens up the quench area correct? which is good for a small amount of hp, not much though. and i figured since i was replacing them anyways, i might as well get some free power.

 

Local GM said me: "Your Chevrolet 1988 is not programable" and I've burn the EPROM a lot of times.

Some "specialists" into GM don't have idea about advanced questions.

 

Stock engines come with a metal shim gasket which is .015 thick.If yours had a composition gasket its been replaced at some time.Put the metal shim gasket back in.

 

Stock head gaskets on 3rd gens aren't always just a steel shim. I just took apart my original 92 Camaro's 305 TBI engine and the gasket was a steel shim skeleton with composite stuff above and below (which ripped off and stuck to the block and heads upon disassembly, making it impossible to Mic it and determine it's original thickness). I think GM gave up on true steel shim-only head gaskets a long time ago. Somewhere in the 80s they started using composites or at least partially composite gaskets.

Like RB says, you probably can't order a true and exact replacement for the original assembly line-installed gasket. You can only order a "service replacement" part which may or may not be an exact duplicate (probably not).

I have used the GMPP .028" head gasket (P/N: 10105117) and it's a solid piece. I have them in the supercharged engine in my Malibu right now (as well as 3 other motors). No compalints. I used to use Fel Pro .039" "blue" gaskets but the GM piece has become my go-to head gasket especially on engines that have not been decked and still have the pistons riding .025" in the hole, just like stock.

 

Actually, I started running into Victorcore gaskets on factory motors in the mid 70s.... the first one I can recall seeing was in a 74 400, that I was working on in about 78 or so

 

learn something new everyday still try too run as thin as you can though

 

so basically what everyone is trying to say is that gm put all kinds of different gaskets on there heads, and the only way to find out is to take it off and mic it. the gm parts guy said it should be stamped on the gasket what the compressed thickness is, is this true?

so your saying that i should run the .015 shim gasket, since that is the thinnest one that i can find?

 

The steel shim gaskets don't seal all that well on blocks and heads that aren't perfectly flat.

 

ok the 10105117 has stainless steel faces on both sides and the 14096405 has stainless steel on one side and graphite on the other. they both have a compressed thickness of .028, which one would be better and why? thank you guys for all of your help.

 

does anybody know of a replacement gasket for a 305 that has the same thickness as the original (.015") I have a spare set of heads. I'm thinking real hard about trying to port them, and when I put them on, I'd like to find a gasket that won't cost me compression.

I've looked up what I could find on felpro, mr gasket, and rol's websites, but none of them mentioned a 305 gasket in .015 thickness (steel shim, composite, or otherwise). The only thing I found was a .01(or.018...can't remember) steel shim gasket, but it was a 4.10" bore (350 block?). I realize that will fit, but I'd like to find one closer to the 305's bore size (3.8??)

anyone?

 

I can't find any 305 specific head gasket. There are lots of .015", 4.0" bore shim gaskets out there.

 

oh well, i guess that will have to do

 

 

I only have experience with one of those gaskets (the cheaper one). The other one you listed is a little more money ($21/ea. vs. $15/ea.). I would ask them for their recommendation. One might only work with cast iron heads, or only with aluminum or or or.......

It's almost certainly a difference in intended application. They're too close is specs and price to justify selling 2 different gaskets unless their intended applications were different

 

ive decided to go with the 10105117 gaskets. i read a couple of post about people spraying aluminum paint or copper coat on the gasket prior to installation, should i do this? do i spray both sides or just one? and when it says aluminum paint, does that mean a paint the color of aluminum, or any color of paint for aluminum parts?

 

just as an update for this thread for search purposes

i found that 10105117 was a revised cylinder head gasket design, tsb 892836A per alldata.

its a better sealing head gasket....as far as thickness goes id like to know mine came out in 3 pieces...wasnt blown or leaking doing it for maintince, and cause the motor was apart anyways.

 

on the factory steel gaskets i pulled apart an 84 lg4 that had steel shim type gaskets

did not measure thickness at the time and they a looong gone now , just thought i would throw this out there