moving comp up 1/2 point.

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moving comp up 1/2 point.

Post  ROAD RAGE on November 5th 2016, 4:05 pm

What cc dish would I need to raise the comp at least a 1/2point?
Now:
Diamon, 4:4200.
comp ht, 1.445
Volume, -32 cc
.005 in the hole
74cc cj iron head. The new motor will be the same as I'm running, (but) would like to raise the comp to at least 10:5/10:7.. Now its around 10.
Thanks.
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Re: moving comp up 1/2 point.

Post  Doug Rahn on November 5th 2016, 7:06 pm

For an accurate calculation, need stroke, deck height, gasket bore and thickness, and how far down the top ring land is. I have a copy of Diamonds original Excel Spread Sheet or you can use the same thing on their website. http://www.diamondracing.net/tools/
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Re: moving comp up 1/2 point.

Post  Mark O'Neal on November 6th 2016, 2:53 am

4.300 stroke, 6.700 Rod.

About -26.0.

72cc head - 32.0cc - 10.3

86cc head - 32.0 - 9.3


72 cc head - -26.0 - 10.8

86 cc head - -26.0 - 9.7

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Re: moving comp up 1/2 point.

Post  ROAD RAGE on November 6th 2016, 12:09 pm

Thanks Guy's!!!
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