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Will switching from 62cc to 72cc heads allow me to....

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Old 01-06-2011, 10:20 AM
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Default Will switching from 62cc to 72cc heads allow me to....

Hey all i just bought an SS 2 days ago with a 402 in it and the heads have been milled to 62cc giving the motor 11.2:1 CR. I was wondering if 72 cc heads are the largest available and what would that lower my CR to? Contemplating going forced induction eventually and would like to know if that's possible with this motor on pump gas, no meth setup. Any insight would be very much appreciated.

Thanks!
Old 01-06-2011, 10:55 AM
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Originally Posted by PRAY HRD
Hey all i just bought an SS 2 days ago with a 402 in it and the heads have been milled to 62cc giving the motor 11.2:1 CR. I was wondering if 72 cc heads are the largest available and what would that lower my CR to? Contemplating going forced induction eventually and would like to know if that's possible with this motor on pump gas, no meth setup. Any insight would be very much appreciated.

Thanks!
Going to that chamber size will get you down to around 10.1 and with pump fuel on that compression you won't be able to run much boost. If you know what gasket you have you could possibly put a thicker one on and drop more compression. For example taking your setup and putting on the 72 cc heads and if there was a .041 gasket and replace that gasket with a .051 it shoud drop it to 9.8.
Old 01-06-2011, 11:16 AM
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10:1 and pump with Meth will be fine. I have been running my 9.9:1 CR motor with 93 and Meth at 13# no problem
Old 01-06-2011, 11:23 AM
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He stated no meth in his original post but I don't think he will be able to pull it off without meth.
Old 01-06-2011, 11:26 AM
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Ah missed the no Meth part. IT could be done but you would have NO timing in it. Add Meth and crank that boost up
Old 01-06-2011, 11:28 AM
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I don't have a clue where to get meth from? I live out in the country so how does one obtain it??

Never thought about the gasket thickness. Good call!
Old 01-06-2011, 11:34 AM
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You can get Meth From anyplace that sells VP products. 5 gal lasts me about 4k miles and only cost like $35 for 5 gal.
Old 01-06-2011, 11:47 AM
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Wow i had no idea it was that affordable! I would def be willing to use it then!
Old 01-06-2011, 11:52 AM
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I don't run meth but I was under the impression that you can run the 50/50 that is sold as windshield washer fluid at any autoparts store.
Old 01-06-2011, 12:10 PM
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Also you can put yellow bottles of HEET in the washer fluid to up the methanol content, supposedly that stuff is 100% methanol and is only about $1 for a bottle of it. Get the -20 degree washer fluid at Walmart and put two bottles of HEET in it and that should be about 50% methanol and 50% water for about $4 for a little over a gallon.
Old 01-06-2011, 12:14 PM
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Dont AFRs offer 75cc chambers?

but meth is the way to go.
Old 01-06-2011, 12:16 PM
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Originally Posted by Hank Peabody
Also you can put yellow bottles of HEET in the washer fluid to up the methanol content, supposedly that stuff is 100% methanol and is only about $1 for a bottle of it. Get the -20 degree washer fluid at Walmart and put two bottles of HEET in it and that should be about 50% methanol and 50% water for about $4 for a little over a gallon.
Thats highly affordable if accurate!!
Old 01-06-2011, 01:25 PM
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Originally Posted by 3.8redbird
Dont AFRs offer 75cc chambers?

but meth is the way to go.
Nope. But the 245 has a 73cc chamber available.
Old 01-06-2011, 02:01 PM
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E85 is the other option if available at the pumps in your area,

you may be able to leave compression as is with E85.....
Old 01-06-2011, 02:12 PM
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**** i WISH!!! I'm lucky to have a BP with 93 oct here where i'm at in the country!



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