So I toasted my old 302 and had a spare in the shop, pulled the donor apart to freshen it up a little, new rings , mains and conn rod bearings. It was a low mileage motor had 83,XXX miles on it still had good cross hatching in it. I hit it with a hone and put everything back together, torqued to spec, everything spun fine and went together well. Got it back in the buggy, put it all together hit the starter button and it was seized. Pulled the valve covers and loosened up all the rockers pulled the plugs and the push rods. Still locked up! pulled the front off removed the timing chain spun the cam fine but the rest was still locked up. Dropped the pan and started undoing conn rods till got to the #4 and #8 cylinders and undid them and presto spun free. So pulled the motor pulled the heads and removed the two offending pistons, and everything looked perfect:confused: just finished putting it all together again and it spins fine its a little tight though I have to use two box end wrenches on the crank bolt to get it to turn, should I keep going and put it all back together and put it in or is something wrong:(

Any chance you put the conn rod caps on backwards with the first install? I would plasti- guage to check clearances on the offending rods.

I would plasti- guage to check clearances on the offending rods.

X2, all bearings not just the 2 that freed it up. What did you use for assembly lube?

Spun fine first time assemled and after re-assembly is tight? Something's going on.

Were all the caps equally tight when you tore it down after it was locked up?