To maintain proper rocker assembly geometry it is imperative that the distance from the camshaft to the top surface of the cylinder head be kept as near as possible to original. You'll note that if the block or cylinder head have been surfaced the pushrods now effectively rise further even in the "down" position. This does not give you more lift, in fact in severe cases it will reduce lift, and in any case it will increase wear and noise. The easy and only solution to this dilemma is to raise the rocker assembly by shimming the rocker pedestals. These shims are .090" thick and can be stacked to the height necessary. Sold individually. Will fit all A series motors.