LT1-LT4 Modifications 1993-97 Gen II Small Block V8

head gaskets/milling heads

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Old Aug 5, 2010 | 12:18 PM
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Default head gaskets/milling heads

Trying to figure out how much I need to mill my heads to get to 11.6.1-11.7.1 compression. I will be using a .028 impala headgaskets, ive searched and cant not figure things out.


from what ive read around .025?
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Old Aug 5, 2010 | 12:45 PM
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is this a stock bottomend??
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Old Aug 5, 2010 | 04:48 PM
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357

speedpro slug, 5.7 scat i beam, stock crank, studed main
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Old Aug 9, 2010 | 11:54 AM
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anyone??
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Old Aug 9, 2010 | 11:57 AM
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The head gasket should be the variable, not how much you mill off of the heads.
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Old Aug 9, 2010 | 12:00 PM
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Originally Posted by RamAir95TA
The head gasket should be the variable, not how much you mill off of the heads.

I dont understand exactly what you are saying?? confused
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Old Aug 9, 2010 | 12:04 PM
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It is not practical to mill X amount off of the heads to achieve your desired compression ratio when all you need to do is adjust the head gasket thickness.

Have you had your current combustion chambers CC'd?
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Old Aug 9, 2010 | 12:10 PM
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No they are still stock, the reason why I plan to mill them is because I dont think I am going to jump from 10.4.1 to 11.6.1 with Impy gaskets alone.

from the thread searches Ive done the thinest gaskets are the impy ones. Is there anything thinner than that?
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Old Aug 9, 2010 | 12:18 PM
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The bigger bore is going to up the compression too. Plug your #'s into a compression calculator.
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Old Aug 9, 2010 | 12:20 PM
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If they have never been milled before, go ahead and mill them down to clean them up. You can get thinner than .028 - Cometic gaskets can be ordered thinner, but they are quite expensive. Any work done to the block? What's your deck height?
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Old Aug 9, 2010 | 12:22 PM
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Originally Posted by speed_demon24
The bigger bore is going to up the compression too. Plug your #'s into a compression calculator.
I think you meant to say the larger bore will drop the compression.
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Old Aug 9, 2010 | 12:42 PM
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Well I have a knock in the bottom end. I am pretty sure its a wrist pin or rod bolt, Ive had a few friends with 5-6 f-bodies and vets all check it out and that is what they think my issue is.

I am not sure on the deck height or anything else really(i would say they are stock). The heads and intake I have were done by one of the guys who has 5 cars back in 96.

I know he gasket matched them and did a valvejob. since they are opened up a bit I think they would drop the compression and than I will be on a 40 over bore dropping the compression further.
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Old Aug 9, 2010 | 01:31 PM
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Originally Posted by RamAir95TA
I think you meant to say the larger bore will drop the compression.
It will increase the compression...
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Old Aug 9, 2010 | 01:36 PM
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Originally Posted by RamAir95TA
No, it won't.

Go plug a 4.030" and a 4.040" bore into a compression calculator and tell me what you come up with.
You probably should have done that before you made this post.
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Old Aug 9, 2010 | 01:39 PM
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Definitely.

Now I'm going crazy. Hah. Oh well. You win.
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Old Aug 9, 2010 | 02:05 PM
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Originally Posted by speed_demon24
It will increase the compression...

If the bore gets bigger how does the compression go up?? its going to be a bigger chamber??

You wana shed some light on this??
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Old Aug 9, 2010 | 02:30 PM
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you need to measure how far the pistons are in the hole first, then go from there..

if someone else built the engine, they may have decked the block to start with, you need to make sure either way.. then you go for the quench measurement... think it would be more important than compression alone..

Last edited by brucer; Aug 9, 2010 at 02:37 PM.
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Old Aug 9, 2010 | 03:15 PM
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no the shortblock is stock. I really doubt someone decked the block, I got the car when it had 57K on it.
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Old Aug 9, 2010 | 09:23 PM
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i thought you said it was bored? if its a 357 its .040 over... thats not stock.. block couldve been decked, you need to check it to make sure..

anyways,
to figure the compression correctly you need to know how far the pistons are in the hole to start with.. then you go to the compression calculator..

Last edited by brucer; Aug 9, 2010 at 09:29 PM.
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Old Aug 9, 2010 | 09:25 PM
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Originally Posted by brucer
i thought you said it was bored?

It will be this week. otherwise stock, i was talking about the current deck height.
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