Yes, sort of like the way we would check for piston/valve clearance on the racing engines. The closest piston/valve position comes at the top of the exhaust stroke, as the exhaust is closing and the intake is opening. Stovebolt exhaust valves are not a problem, as they sit in a deep recess in the combustion chamber and it's impossible to touch a piston. Intakes are a different situation, as they sit almost vertical right over the piston. I position a magnetic base dial indicator with the stem on the spring retainer, and as the piston approaches top dead center of the exhaust stroke, I use a pry bar to push the valve down until it touches the piston. Measure the clearance- - - -move the crankshaft a few degrees, and check again, etc. Depending on the cam position and rate of lift, the closest clearance may, or may not happen right at TDC. The rule of thumb for many years has been to have a minimum clearance of 1/16" at the closest piston/valve position, whether it happens at TDC or not. Some cams with high lift rates have the valve outrunning the piston near the top of the stroke. One race engine I built had the closest valve/piston position happening at 15 degrees AFTER top dead center!
Jerry
