ProComp/Speedmaster aluminum heads
Did you read post 1374 the second to the last one on the last page?..
Yeah, I read it before and just read it again to refresh my memory.
That’s the problem with the shims that Hughes sends out. They only raise the shaft, they don’t move it away from the valve.
Again, the math is WAY over my head, but you are working with an arc that the rocker works on, around a fulcrum. And it moves a valve that moves up and down (I hope Mike sees this and comes by and corrects me) while the rocker moves about its fulcrum.
If you take a straight edge and lay it against the valve or valve spring and then use another to simulate the shaft (fulcrum) you’ll see that as the get longer (move away from the head for the valve and like you are raising the shaft) you’ll see they not only get closer together the further away from the head you get, but they actually cross.
That’s why you can’t just add longer valves, or a roller tip or both without raising the shaft AND moving it away from the valve. Otherwise, the two will move closer together and the geometry is never correct.
And yes, you’ll need longer pushrods when you correct the geometry. You’ll be raising the shaft enough that the push rods you have will be way too short.
