if you are building your motor, yes. If your motor is together, i used to put the collar low on the distributor shaft and snug the set screw so it would move, but stay where it stopped. Use grease to hold a 1/2 inch id washer .010 to .020 thick, made of paper or plastic to the bottom of the thrust spacer so it will leave a .010 to .020 gap between the pump drive gear face and the thrust spacer. Install the distributor and torque the hold down. Remove the hold down and distributor and tighten the set screw. Remove the washer and reinstall the distributor with the thrust spacer. Torque the hold down.