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Old 05-10-2007, 08:59 PM
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rocker arm ration conversion formula?

There was a formula posted fairly recently for converting the valve lift when changing from 1.5 to 1.6 ratio rocker arms on a SBC. I think it was BLAZIN 72 that posted it. Anyone know it? Thanks.

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Old 05-10-2007, 09:02 PM
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http://www.wallaceracing.com/rockercalc.php
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Old 05-10-2007, 09:08 PM
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it's really simple. devide 1.6 by 1.5 and get 1.0666. Multiply the lift at 1.5 by 1.0666 and get the lift at 1.6. .5 lift at 1.5 rocker arm ratio will be ,566 at 1.6 rocker arm ratio.
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Old 05-10-2007, 09:26 PM
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Oops I made a mistake. set it up as a proportion. Old ratio over new ratio = old lift over new lift. Then cross multiply, New lift equals new ratio times old lift devided by old ratio. Or 1.6 times .500 divided by 1.5 equals new lift. .533.
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Old 05-17-2007, 01:01 PM
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Multiply original lift x 1.067
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Old 05-17-2007, 08:14 PM
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Or you could divide your valve lift by your current rocker ratio then multiply that number by the new rocker ratio.

Like this: .480" lift(current valve lift)/1.5 (current rocker ratio)=.320 Multiply that by 1.6 (new rocker ratio) and you get your new valve lift of .512
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Old 05-19-2007, 09:48 PM
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rocker ratio formula

Quote:
Originally Posted by junior stocker
There was a formula posted fairly recently for converting the valve lift when changing from 1.5 to 1.6 ratio rocker arms on a SBC. I think it was BLAZIN 72 that posted it. Anyone know it? Thanks.

lobe lift X rocker ratio = lift at the valve(gross)
eg:.316 x 1.5:1 = .474
eg:.340 X 1.5:1 =.510

with a 1.6:1 rocker ratio:

eg: .316 X 1.6:1 = .5056
eg: .340 X 1.6:1 =.544

A quick way to convert the lift at 1.5 to lift at 1.6 is;
Multiply lift by 1.066666

eg .510 X 1.066666 = .544
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