With the crankshaft in place, we then checked the thrust without the rear main cap on. We placed a dial indicator at the front of the crankshaft and set it to 0. Next we gently placed a flat-head screwdriver between the counterweight and the main and applied some tension back and forth for a reading. Generally, on performance applications you'll want no less than 0.006 inch. High-boosted applications or extreme clutchless-type race cars will demand more clearance.