[Fot] roller rockers and head flow

[Richard Good]

Rocker ratio has everything to do with valve velocity.  Lifter velocity 
times rocker ratio equals valve velocity.  Boring the block and 
installing .874" Ford lifters instead of .800" stock lifters allows the 
cam to be ground for 13.6% more lifter velocity.  Changing from stock 
1.45:1 ratio to 1.65:1 ratio rockers increases the valve velocity 
13.8%.  Do both and you get a 29% increase in valve velocity.

Richard Good
Good Parts

William G Rosenbach wrote:

>Terry,
>Interesting stuff. But one question. You state:  
>Because these engines are so restricted by the valve & seat, then 
>the only way to improve them is by having very fast lifting cams and
>therebye
>having the vale open for the longest possible duration. The rocker
>arrangement has little to do with this.
>Doesn't the increased rocker ratio cause the valve to move faster as well
>as further?
>Or is it just a case of to little a change to make a measurable
>difference.
>Thanks,
>Bill
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