FWIW, GM specs the OEM MLS gasket for that application at .052 thickness compressed.

I'm curious to see what the pistons come up as. I believe there listed with an 8cc dish

 

.052 does make my compression calculator work better but still not with a 8cc dish. More like a 6 or 7.

I still haven't measured the dish in the piston yet. But I did fix my clutch the is weekend so... I'll get to it.

I ran that gasket thickness against a 5.3 HO set up with 243's (as they came) and it made the compression ratio come up correctly with 9.9:1.

So with that gasket thickness my compression will be higher then I expected like a couple of you have said. Thanks for the info guys.

I'm attaching the new calculation with the .052" head gasket thickness and unmilled heads.

 

I got 10.38:1 for your current calculation on your pic. because if it's for a 5.3 ho with 243s has 64cc chambers

 

nah, I'm running 862's (61cc). That last pic I posted was with them unmilled also. I'll probably still mill them some. Aiming for 10.5:1

 

She'll run like a champ at 10:5.1 cr

 

Yesssir! That's what I'm thinking.

 

You were right sir! I just measured one of the old 5.3 dished pistons and it came to 8cc. I even measured it twice because I subconsciously didn't want to believe it. lol Thank you for chiming in.

Now i've got to go over my numbers again and play with the compression calculator some more. I probably won't be milling my heads as much as expected.

 

but now with those numbers my compression isn't adding up correctly for the stock compression ratio of 9.5:1. Am I missing something?

 

I just measured the old gasket that came off of this 2001 engine. It measured .060". I'm not sure what its made of. It doesn't look like graphite or MLS, but I could be wrong. Its part number is 12558940.

This messes up my numbers even more. Did the early 5.3's have lower compression?

 

The early ones used a Graphite gasket. Try another calculator just for ***** and giggles.