NeverT00fast

iTrader: (4)

I'm trying to find out what's the thickness of a compressed stock GM MLS head gasket, on the 5.7L and the 6.0L gaskets.

I did a search and found a few numbers but nobody was really sure. Some said .060, .054, or .051 on the 5.7s, and .054, .052, or .051 on the 6.0s.

Does anybody know for sure what the compressed thickness on these gaskets are?

PREDATOR-Z

My 6.0 MLS is .050 compressed, 5.7 gaskets are .060 (as per a motor builder that uses them a lot)
This is average and can vary +/- .02

NeverT00fast

iTrader: (4)

Is it safe to use the 6.0 gaskets on a 5.7 block?

PREDATOR-Z

6.0 gaskets are 4.060 bore

SS4Matt

iTrader: (4)

that's what i've been running for about 2 years now...6L mls gaskets with my patriot ls6 (2.055/1.60) "stage 2" or something heads on a '98 5.7.... so that's my $0.02

ChevyChad

iTrader: (50)

I'd also like to know this since I plan on using 6.0L heads on my 5.7 block.

Umm that doesn't really answer the question??

GuitsBoy

iTrader: (4)

measured an old set of mine at .053 - .055. The 5.7L MLS I mean.

slowride

iTrader: (3)

X 2

Both my old and new set of GM MLS gaskets were .053-.055 as stated above.

ArcticZ28

iTrader: (14)

6.0 gaskets AFAIK are 4.030, not 4.060. Regardless, using them on a 3.898 bore (5.7) will open up more area for detonation. Not worth it, in my opinion. Just use the stock GM MLS gaskets for the 5.7 engine if you are using the stock LS1 bore heads. However, if you are using heads like 317's with the 4.000 bore, then you would want to go with the 6.0 head gaskets. You want to use gaskets for the largest bore of your head/engine pair.

NeverT00fast

iTrader: (4)

.053-.055 sounds good. I'll be running the TFS 215cc, so stock bore.

Prey4Me

iTrader: (2)

Is 3.898 the stock bore size for the 5.7? I need head gaskets and have AFR 205cc heads, what would be the correct gasket to use? This motor will have nitrous soon if that makes a difference. I'm looking at cometics, and not sure which bore is called for in this case.

chriswtx

iTrader: (5)

same here, my old 5.7 mls gaskets measured .054

hammertime

iTrader: (1)

If the deck surface outside the combustion chamber is all flat, wouldn't you want the head gasket to match the bore diameter? Is the chamber actually .100 wider on a 317 head than a 243?

ArcticZ28

iTrader: (14)

I would go with Cometics if you're gonna spray. Cometics offer a wide range of bore and thickness sizes for you to go with. The stock bore for the 5.7 is 3.898 and the GM MLS 5.7 gasket bore size is 3.905, if i recall correctly. With the AFR 205's and the stock bore (5.7) I would go with a Cometic 3.905" bore and .040" thickness. This would give a better quench than the stock MLS gaskets so it would suit you much better, especially when using the juice.

ArcticZ28

iTrader: (14)

A 317 head is 4.000" bore rather than the stock 3.898" bore. So yes, you would want the head gasket to match the larger bore (if you were using 317's), which the stock GM MLS 6.0 gaskets match well.

PREDATOR-Z

No, I run these on my 4.030 bore 370 and I measured them. They are 4.060 bore.
There might be 2 types of 6.0 MLS but I don't remember. I know mine are 4.060

You do not use a gasket that overlaps your bore, it is always a bit bigger.
Using a bigger bore gasket has no detonation issues, but you loose compression and you do not want the gasket bores to be beyond the cylinder sleeves, because upon charge explosion, you do not want the sleeve/block area to be exposed.
Using bigger bore gasket actualy increases your quench areas, which at proper thickness is not bad.

ArcticZ28

iTrader: (14)

Gotcha. I wasn't 100% sure on the bore on those, but now that you mention it it makes more sense for them to be 4.060. I'm not quite sure I follow in the same line of thinking for the detonation issue of using a larger bore gasket. Using a larger bore gasket does increase the quench area and thus increases the area for detonation. You want the gasket to be tight around the bore so as that it does not encroach into the cylinder but also does not allow the combustion to travel further outside of the bore/sleeve area between the block and heads. I think we may be saying the same thing here, even though we may not be agreeing on the detonation issue.

Prey4Me

iTrader: (2)

Thanks for giving answers that I can understand. Some of this stuff can get confusing real quick! The only thing now is waiting 3 weeks for them to get here . Thanks again for making things easier to understand .

BADFNZ

iTrader: (19)

It really doesn't matter because GM doesn't make 5.7L gaskets anymore. All the part numbers were superseded by the 6.0L gaskets. I went through this a year ago when I was doing my head swap. I had to use the 6.0L gaskets on my stock bore engine and haven't had any issues at all.

ArcticZ28

iTrader: (14)

No problem, glad to help.

BADFNZ - According to your sig you're about to get a "vacation *******". I'd assume this one differs from your hard working ******* that never takes one