OK, all you old hands, I admit it, I need help. I have taken apart several Model A engines but this is the first one I've tried to put back together from scratch. (Actually, it's a late B motor with CW crank if that makes a difference.) I can get .0015 clearance as recommended by Les Andrews on the front and center mains and the crank will then turn with less than 25 ft-lbs torque, just like the book says to do. Then I get the rear main to .0015 to .002 clearance (plastigage) and the crank won't turn at all. I read about .002 clearance on the thrust face of the rear main. What am I doin' wrong? With the front and center main caps loose and the rear tight at .002 plastigage I still cannot turn the crank. Should I recheck the thrust clearance? How should I get more? Step by step now, please. Thenks in advance.