There was another thread about smallblocks and lash settings, I wanted to get dome real hardcore racers to respond to this.

I was playing around in Autocad where I modelled a "perfect" 45 degree lifter bore essentially parallel to the cylinder bore and the pushrod perfectly straight and on the bore centerline of the lifter in all directions going to an imaginary Perfect Rocker.

Of course it's not but I do know that pro stock racers picked up a lot of RPM by modifying the blocks and even shifting the cams and lifter bores in order to get the pushrod as short and in as straight a path as possible.

That brings us to the 59 degree which means the cams lift has to compensate for a 14 degree offset and this results in an oscillation of the pushrod as it doesn't move in anything close to a straight path from the lifter cup end or the rocker fulcrum. The loss of actual cam lift on say a gross 600" lift (1.5 rocker with a .400 lift base circle) looks to be in the .030" loss of lift...not even considering lash.

My 'Theory' is a small block 59 would benefit from as little slack as we can get away with, That oscillation "wobble" (even at 1/2 the crank speed) would be likened to trying to drill a hole with a bent drill bit. To my knowledge Hot lash measured at the valve stem for say a SB Chevy with obviously better pushrod geometry and therefore a better chance at a true "as advertised" rocker ratio would be proportionally looser on a Mopar and allow the pushrod to "rattle" more between the rocker cup and the lifter cup.

My cam is listed as .016/.018 HOT so with aluminum heads I was setting the feelers (-.006) so .010"/012", (which should be ~.008) at the adjuster but of course that will grow between the cups as the motor heats up.

I'm just wondering if anybody has run them significanly tighter and seen any better results. It doesn't "seem" like a lot of "wobbling but I'm thinking every thou you can run it tighter between the cups without binding the springs might allow it to rev easier, if not noticably higher. It's like to me the small block has an extra degree of "slop" in the system.

Back in my early 20's I had a w2 340 and I turned it 7600 with an Isky 3/8 mile circle track cam (no doubt based off a chevy) , back then i was more worried about the clutch exploding than what my Ductile iron (non roller) rocker were doing!! But after a year or so of hard use you could see those rockers really took a beating!