I check bearing clearance without a rope seal in place, it gives a more accurate reading. Do the check with the PG on a dry spot on the shaft, as it tends to dissolve when it comes into contact with oil. That's intentional, so any residue doesn't contaminate the lube system. Too tight- - -get your machinist to polish the shaft for a bit more clearance. Too loose- - - -regrind the crank to the next smaller undersize.
A more accurate method of determining oil clearance is to measure the inside diameter of the bearing with a dial bore gauge, and measure the crankshaft diameter, and do the math. That's how we build race engines. Plastigauge is a good compromise for checking street engines.
Jerry
