Is .028 quench to tight?

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May 5, 2010 | 05:05 PM

monte383sbc

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From: bayville/howell nj

Is .028 quench to tight?

i finally got my mahle -4cc pistons in with my stock crank and ls2 rods, now i checked my deck height and i came up with .011-.012 deck height will i have enough room with .040 cometic head gaskets which would be .028-.029 quench? also this is gunna be my daily driver with 11:1 compression and running on 93 octane. any help apprciated thanks matt

May 5, 2010 | 05:39 PM

itsjustaSB

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From: indiana

i would try and keep it in between .035 and .038 for the quench seems tight to me from everything i have read

May 5, 2010 | 05:45 PM

1989GTA

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IMHO that is to tight. However you probably will find a few people running that tight. I think you will find that most people shoot for .035" to .040". Maybe trim .006" off the pistons?

May 5, 2010 | 06:15 PM

davidws6

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From: Kansas

Daily Driver ? What's your rev limit set to ?

I'd say .030 is the min but you'd prolly be ok if you don't rev it crazy...

May 5, 2010 | 07:51 PM

monte383sbc

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From: bayville/howell nj

i guess it looks like iam goin with a different head gasket then, anyone intrested in new cometic 3.910 .040 head gaskets?

May 5, 2010 | 08:38 PM

crainholio

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Quote:

Originally Posted by monte383sbc

i guess it looks like iam goin with a different head gasket then, anyone intrested in new cometic 3.910 .040 head gaskets?

0.040" compressed thickness, and you're calculating 0.028" quench?

Did you deck the living daylights out of the block, or are you running whacky pistons that are 0.012" above deck?

May 5, 2010 | 08:58 PM

mark21742

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From: PA/MD

I'd run a .051" gasket to get as close to .040" quench

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May 5, 2010 | 09:08 PM

crainholio

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Quote:

Originally Posted by mark21742

I'd run a .051" gasket to get as close to .040" quench

If the pistons really are 0.011" out of the hole because of decking machinework, and he'll be revving the snot out of it, sure.

I'm hoping he will re-check his math, though. I've never seen a Mahle piston with crazy deck heights, they like that #1 compression ring to have plenty of safety margin.

Running tight quench is great for combustion efficiency and detonation resistance as long as the rods are up to it.

May 5, 2010 | 11:18 PM

#10

monte383sbc

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From: bayville/howell nj

Quote:

Originally Posted by crainholio

0.040" compressed thickness, and you're calculating 0.028" quench?

Did you deck the living daylights out of the block, or are you running whacky pistons that are 0.012" above deck?

let me recheck my d/h , ive bin told a few different ways to check it, what is the corect way to check my deck height?

May 5, 2010 | 11:20 PM

#11

monte383sbc

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From: bayville/howell nj

Quote:

Originally Posted by Bad Notch

Damn, I'd trade you my new .045 Cometics for your .040 if your interested.

i may take you up on that trade after i check my deck height agin, thanks

May 5, 2010 | 11:39 PM

#12

LLC

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Quote:

Originally Posted by monte383sbc

let me recheck my d/h , ive bin told a few different ways to check it, what is the corect way to check my deck height?

How are you checking it now?

May 6, 2010 | 12:00 AM

#13

monte383sbc

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From: bayville/howell nj

Quote:

Originally Posted by LLC

How are you checking it now?

i checked it buy putting the piston at true TDC and rockin it bak in forth with a dial indicator on each side to get it straight up, the i used a tru straight edge and ran a feeler gauge under it, ill recheck it tommorw

May 6, 2010 | 09:33 AM

#14

Sales2@Texas-speed

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From: Texas!

Quote:

Originally Posted by crainholio

I'm hoping he will re-check his math, though. I've never seen a Mahle piston with crazy deck heights, they like that #1 compression ring to have plenty of safety margin.

From my experience, it's not real unusual at all for Mahle's to set up .005-.010" out of the hole.

OP: What piston part number are you running?

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May 6, 2010 | 10:01 AM

#15

jmm98LS1

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From: KS

My mahle flat tops sit .012" out of the hole with just a light cleanup pass on the decks.....

May 6, 2010 | 10:37 AM

#16

99LS6SS

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From: Joplin, MO

I thought a tighter quench was better. I'm glad im reading this thread

May 6, 2010 | 12:39 PM

#17

1989GTA

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"I thought a tighter quench was better."

It is but you can have too much of a good thing. You do not want the pistons hitting the heads as that can result in broken parts. As said above it appears most builders shoot for the .035 to .040" range. If you have the money and time you can sneak up on the quench and see when the pistons just start to kiss the heads. Most of us except for the racing teams don't have the money or time to experiment for such a small gain.

May 10, 2010 | 09:29 PM

#18

monte383sbc

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From: bayville/howell nj

Quote:

Originally Posted by Matt@Texas-Speed

From my experience, it's not real unusual at all for Mahle's to set up .005-.010" out of the hole.

OP: What piston part number are you running?

iam not sure ill try to get the number tommorw

May 10, 2010 | 09:35 PM

#19

monte383sbc

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From: bayville/howell nj

ok i checked my deck height again for the 50th time and iam coming up with .010-.011 out of the hole with the piston flat, and i came up with .023 rocked on one side and .024 rocked on the other side, soooo what is the minimum gasket i should go with .045 cometics, i have a set of .040s but that seems to tight of a quench, thanks for the help matt