Percent of lost lift due to 58 degree lifter angle?

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Thanks for all the replays. This smallblock stuff is all new to me, at least getting into valvetrain mods, like the conversion of my magnum build to svc rockers.
 
yellow rose said:
That's what I figured. Having the geometry off compounds area lost but doesn't really change net loss.

Did I get that correct?
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It can affect both, but most people only notice the net lift numbers. If it has the correct net lift, the geometry must be right, right????? ......Nope!
 
The loss of lift is not due to the lifters angle with the cam, but the pushrod's angle with the lifter. So to calculate, take the lobe lift times the inverse cosine of the angle of the pushrod relative to the lifter at mid lift. Then multiply by the rocker ratio to estimate lift at the valve. Note that this is a slight oversimplification because the angle changes as the lifter rises. Keep in mind also that the pushrod is at an angle both along and across the cam axis, so you would need to calculate the resultant vector. If you wanted to go nuts, lift could be calculated over a range of lobe lifts and a curve then plotted showing the variation of valve lift relative to lobe lift. Fun with trigonometry.

The slightly odd pushrod angle is why you can't just multiply the lobe lift by the rocker ratio to get valve lift, even though that's how cams are advertised. The early hemi had the pushrods basically inline with the lifter. When the A (poly) engine came out, the lifter angle carried over so both engines could be built on the same tooling, same story with the LA and Magnum variants. Each time it got a little worse (Magnum worse than LA due to taller lifter).
 
I didn't think this was true until I took Multi-variable and Vector Calculus. Perhaps there IS such thing as too much of a good thing.
 
C130 Chief said:
I didn't think this was true until I took Multi-variable and Vector Calculus. Perhaps there IS such thing as too much of a good thing.
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Yea! chocolate ! Toco bell after heavy drinking, viagra in one doseage (10 hour stiffies!)
 
Thanks again for all you guys posting your thoughts and experience.
This thread has taken a turn into the whole of valvetrain geometry. That is fine with me!
 
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