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Spoke with Indy today , the guy says the CNCd heads come with 79cc chambers , the heads purchased without CNC work come out as 75cc , so these heads were obviously bought without any CNC work from indy (75cc) , looks like i only need to cut around .072" off.

Thanks again.

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We check all our heads before and after milling,the 440-1s usually come up 75cc+ with the heat range spark plug that we intend on running and usually 74ccs- with a soild plug.WE generally cut .041 to get in the 64/65cc range.

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We check all our heads before and after milling,the 440-1s usually come up 75cc+ with the heat range spark plug that we intend on running and usually 74ccs- with a soild plug.WE generally cut .041 to get in the 64/65cc range.

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Bob ,this is where it gets confusing , you say .004" per 1cc , the link on the other thread on moparts say .004" per 1cc , Indy say .006" per 1cc , now i'm obviously gonna check before cutting , but how many take Indys advise & cut too much? , or is there a limit on milling wherby the '006" will change the deeper the head gets milled?

I don't see how the .004/.006 can be accurate due to the shape of chamber...................i would think milling would have to be done in stages , checking every so often.

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you can't go wrong by multiple checks