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317 heads?

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Old Apr 29, 2010 | 06:59 PM
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Default 317 heads?
alright, i searched but couldn't find the answer. i have a set of stock 317 heads that im planning on swapping on to my stock 346 motor with 6.0l mls head gaskets. i want to try to get at least a 9.5:1 cr. what i want to know is what the cc size is on the stock 317 heads cause it seems people think its anywhere between 74cc to 71cc. also, my other question is should i mill them down to 70cc or 69cc to get the 9.5:1 cr.




thanks,
albert
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Old Apr 29, 2010 | 07:47 PM
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I thinks its 72cc stock
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Old Apr 29, 2010 | 11:14 PM
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i always heard 71/72
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Old Apr 30, 2010 | 12:42 AM
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72cc
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Old Apr 30, 2010 | 01:47 AM
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alright thanks, so now that i know what, should i mill them down to 68cc or 69cc to get the compression down to 9.5:1
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Old Apr 30, 2010 | 10:37 AM
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Originally Posted by 03redzo6
alright thanks, so now that i know what, should i mill them down to 68cc or 69cc to get the compression down to 9.5:1
I have bone stock 317 heads, LS2 GM MLS headgaskets, -2cc pistons, and my CR was right about 9.2:1 when I calculated it last year during my build
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Old Apr 30, 2010 | 03:59 PM
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thanks for the info
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Old Apr 30, 2010 | 07:10 PM
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What are the benifits of these heads over ls6 243's?
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Old Apr 30, 2010 | 07:45 PM
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Originally Posted by c3spdrcr20
What are the benifits of these heads over ls6 243's?
They lower the compression, a 243 is 64-65cc whereas the 317 is 72cc and they both flow about the same.
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Old Apr 30, 2010 | 08:06 PM
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12562317 in my gm book says they are 71.06cc and unmolested head bolted on a ls6 block= 9:1 and that they are perfect for supercharging! also has the same intake and ex. port as the z06 243 heads! also says the 243 head is 64.45cc hope this helps
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Old Apr 30, 2010 | 08:23 PM
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Originally Posted by 03redzo6
alright, i searched but couldn't find the answer. i have a set of stock 317 heads that im planning on swapping on to my stock 346 motor with 6.0l mls head gaskets. i want to try to get at least a 9.5:1 cr. what i want to know is what the cc size is on the stock 317 heads cause it seems people think its anywhere between 74cc to 71cc. also, my other question is should i mill them down to 70cc or 69cc to get the 9.5:1 cr.




thanks,
albert
I would not mill them down it will weaken the deck! you will have 9:1 stock .020-.030 inches would give you 9.5:1 look for the thinest head gaskets you can get just my opinion thanks Scott
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