Quote: Brad I would like to see an engine with one theory applied on one head and the other theory on the other. Then check the lift at the valve to see which achieves the most lift at the valve. One thing for sure the set up that has the rocker 90 degrees in relation to the valve at mid lift will have the least amount of scrub.
Mid lift provides the least amount of scrub. Low point (2/3 lift) gives you the least amount of scrub under load. That is, the scrub occurs while the load is low and then when the load is high there is very little scrubbing action.
I think most of the serious valve train designers migrated to the low pivot point design a number of years back. The math is fairly complicated but if you put the rocker arm perpendicular to the valve stem at 2/3 lift you're in the ballpark. The scrub pattern is larger than with the mid-lift design, but the sideways force applied to the valve goes down.
- try reading the book "Valve Gear design" by Michael Turkish, 1946, Eaton corporation. Turkish was a mathematician who worked for Eaton - and Eaton was a tier one supplier to GM - and probably a lot of other automotive OEM's. Yes, the math is well over my head, but pretty much as you alluded to verses the common 50/50 rocker arm arrangement ( 90* at mid lift) that most use today. My brother ( much smarter than I ) has done extensive research in this area also. I was able to grasp about 75% of what he sent me on the subject. Yes, it is a complicated subject and unfortunately, a lot that has been written about it has been written by people working for magazines trying to sell you a product ( those pretty gold anodized aluminum roller tip rocker arms with your initials stamped on them ). So, since this thread has turned in to "who's the smartest", Could I see a show of hands of those with the title of "Mathematician". - I won't be raising mine .
- try reading the book "Valve Gear design" by Michael Turkish, 1946, Eaton corporation. Turkish was a mathematician who worked for Eaton - and Eaton was a tier one supplier to GM - and probably a lot of other automotive OEM's. Yes, the math is well over my head, but pretty much as you alluded to verses the common 50/50 rocker arm arrangement ( 90* at mid lift) that most use today. My brother ( much smarter than I ) has done extensive research in this area also. I was able to grasp about 75% of what he sent me on the subject. Yes, it is a complicated subject and unfortunately, a lot that has been written about it has been written by people working for magazines trying to sell you a product ( those pretty gold anodized aluminum roller tip rocker arms with your initials stamped on them 
). So, since this thread has turned in to "who's the smartest", Could I see a show of hands of those with the title of "Mathematician". 
- I won't be raising mine 
.
