I recently punched a 5.3 block out to a 5.7 (Iron LS1). I finally got my bottom end put in the block, and now trying to figure out head gasket size so I can finish this thing up and get it in the truck before it gets too cold out. When the block was machined, they took a little off the block. I had the heads CNC ported with oversized valves. They are/were 862 heads, without the notch. So I am able and planning on running an MLS head gasket. I'm also running forged LS1 pistons and rods with all ARP fasteners down there. When I measured my piston protrusion height, I'm at .0225 out of the hole. This motor will not see boost. Tried looking for something online on figuring out head gasket thickness based on protrusion, but couldn't come across a straight answer. Looking for input on what thickness I should run, or how one would figure that out? I was reading that forged rods stretch less, and a bunch about quench values... Below are a couple pictures of what I'm working with...

 

I just read a bunch about quench after trying to up comp and ordering the wrong head gasket. This is the gist out of all what i read, everybodys opinion differs tho.
Good target quench to shoot for esp with a iron block is .035, add that to what your piston deck height is which looks like .022 and that gets you what thickness gasket you need at min.
Since you have a stock ls1 bore and not looking for a boost gasket im betting you might be able to find a cheap stock ls1 felpro with .060 compressed thickness.
I know you said they took some off the block but .022 seems like more than a little, if youve only checked one cyl you might want to check all of them and use the tallest one as your reading..

 

Even .035 is pretty damn tight, mid .04x seems like a good target for quench.

 

0.040 is what I hear is preferred on NA and small power adder type stuff. Big power guys usually go for a little bit more to make sure the piston doesn't kiss the head.

 

Depends on rods. I know a offshore boat engine builder that runs multiple 1500hp big blocks that are supercharged and he runs them in the .030 range but he also has 1200lb spring pressure.

Now if you are running aluminum rods you are going to want more, but I don't know anybody on the site that is running them.

 

Found some guys running .030 over on tech with no problems supposidly, but thats alum block. I guess i should have phrased that differently, i read .035 is the bare min reccomended quench for a iron block from someone reasonably knowledgeable as they had actually found signs of piston contact on a iron block at .030

 

Thanks all for all the info! That definitely helps! I'm going to go back and verify height on all 8, then try looking for something just slightly thicker than 0.060 compressed thickness, that should put me somewhere around mid .040's...

 

it all depends on a lot of factors. bore, piston/wall, rod, rpm, blah blah blah
i had a 385" sbc at about 032 and the shape of the chamber was clean on the piston because they were so close while running.
i prefer to run quench as tight as i can but the trend over the past 4-5 years in big power adder stuff is very large quench and big open dish pistons. i dont like that idea at all but im not making big power and those guys are.

 

.040-.042 is what i shoot for quench when i
build a motor

 

I would Run it in the .035 -.040 range quench for NA.

The pistons were probably specced for an LS1 Block which is .010 taller than the Iron blocks.

LS1 Aluminum Block is supposed to be 9.240
Iron block is supposed to be 9.230

This would explain why they are so high out of the hole. Not because it was decked excessively. They usually do a minimal clean up on blocks such as .003 to clean surface as well as remove any taper.

Verify all the piston measurements including piston rock on the high and low side.