Mid-lift vs Low-pivot rocker arm geometry

[Walter R. Malik]

They should already be 50..........

So:

Get the valve geometry right using mid lift using a properly designed rocker arm so the pushrod side is correct as well.

Easy... I think we're done here...

The issue is that people using aftermarket rocker systems at whatever lift figure they have, is mostly a different mid-lift number for every application.
Those people don't design their own rocker arms and are relegated to using what is already in the marketplace.

A rocker arm designed for .500" maximum valve lift will not be correct on both sides at .750" maximum valve lift so, it is required that you work with whatever you have to probably arrive at the best compromise.

[GARY C]

I haven't heard anyone say anything about the fact that low pivot opens and closes the valve slower. Anyone care to comment on this.

My opening post on this thread mentioned "Even if it's fairly subtle, the lift curve is going to vary between the two..." in reference to what you're saying. However, that area of the discussion never caught much traction.

Well it could be a way to tune out spring surge or at least help

My guess is that few people ever mock up an engine with different rockers and track this motion and then test the results of one vs the other, not to mention that finding the data of a rockers ratio variations before purchase is probably impossible outside of the few listed in DV's BBC book, so you would either have to special order variations in one brand or have a bunch on hand.