Check for piston-to-valve interference (which should have been done on assembly). Get the piston to exact top dead center by either probing into the cylinder through a spark plug hole with a piece of soft wire as you slowly turn the engine as the exhaust valve closes, or using a degree wheel. The intake will be opening at that time, and if the clearance is too close the valve will hit the piston. Once the piston is at TDC, use a pry bar on the intake rocker arm to check how much travel it takes to make the valve touch the piston. If it's less than 1/16", tear the engine down and use a flycutter to put a slight eyebrow in all the pistons at the potential contact area. Been there, done that, on hundreds of racing engines!
Jerry
Last edited by Hotrod Lincoln; 11/13/2013 4:28 PM.
