400 low buck dont give a

well went to put the main bearing in the motor today and ran into a problem ..i like to install the bottom bearing and turn the crank to make sure its free and get a feel for it... so i installed the bottom bearings and then start the top caps and bearing,i put all the bearings in the caps with ***. lube and then install the bearing and place them where the go..i like to start in the midd. and go out 1 in 1 from the midd. so i start in the midd. and run the bolts down by hand and damn crank no longer spin.. what the hell.. the mains out the motor are at/20 74 and i ordered new 20under main bearing:violent1::violent1::violent1::violent1: so now i am stumpped what the hell is going on.....is there diff. bearing for the 400 block or something????:wack: i hate this cause its going to cost me time and more money if the bearings are diff. but hey what do i know...an now i will be gone out of town working..leaving tonight for va...something all the time...as far as the heads go i am going with the 906 heads as long as i have the pv clearence i need to use them, they are already ported and just need to install the valves and springs i need for them.. they came off a running car so i think they will be ok.. as far as the 452 i will try and port them by the templetes i have while i have the time in the shop........