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Flat Top 4.8 Pistons into my 5.3 HOW TO Video Here

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Old 11-11-2013, 09:17 PM
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Originally Posted by AGearHead4Life
The most i've heard on a stock dished LS engine was -7cc and that was for a LQ4 which of course are larger. I've got a 5.3 dished piston on my bench waiting for me to measure. Hopefully tonight.

The most accurate number I've gathered for the OEM MLS gasket was .060". I have not measured myself yet though. Mine are from Summit.
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
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Old 11-12-2013, 08:44 PM
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Originally Posted by 1FastBrick
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.
Attached Thumbnails Flat Top 4.8 Pistons into my 5.3 HOW TO Video Here-53-48-pistons-52-mls-head-gasket.png  
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Old 11-12-2013, 09:07 PM
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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
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Old 11-12-2013, 09:21 PM
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Originally Posted by ltr450ryder
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
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Old 11-12-2013, 09:42 PM
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She'll run like a champ at 10:5.1 cr
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Old 11-12-2013, 10:04 PM
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Originally Posted by ltr450ryder
She'll run like a champ at 10:5.1 cr
Yesssir! That's what I'm thinking.
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Old 11-13-2013, 09:59 PM
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Originally Posted by 1FastBrick
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
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.
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Old 11-13-2013, 10:07 PM
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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?
Attached Thumbnails Flat Top 4.8 Pistons into my 5.3 HOW TO Video Here-compression....png  
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Old 11-13-2013, 11:10 PM
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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?
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Old 11-14-2013, 11:58 PM
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Originally Posted by AGearHead4Life
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?
Originally Posted by AGearHead4Life
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.
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