I am in the middle of a rebuild for my 420a. I am using eagle rods and JE pistons 20 over with aluminum bearings. I put the first piston in and torqued it to spec (75 ft. lbs.) w/ moly lube on bolts and oil on the bearings and the crank turned smoothly. but then I put the fourth piston in (same position as other) and tightened it exactly the same way and now the crank wont budge. the piston moved just fine by itself, and the crank turns when I loosened the rod bolts 1/8 of a turn, but when tightened the whole way, no budge. any advice, ideas?

75lbs of torque? i think its 20lbs and then 1/4 turn. and use assembly lube on the bearings, its better.

75ft lbs is WAY too much for the Eagle rods with ARP studs. I'm not positive, but spec on those is around 26 ft lbs, but someone else should verify this...IMO, get new bearings now that you overtorqued them..Also, when the motor is new(rings have not yet seated), it will be very hard, if not impossible to turn the crank by hand with all 4 pistons in. If you have the crank gear on there, or the bolt in the crank, it should turn with a little effort. There is just a lot of friction within the new rings against the new cylinder wall surface. When i assembled my motor, i had the timing belt crank gear on, and if i turned that with one hand, and "helped" using the other hand to push down on a piston, I could make the entire assembly move.

whoa damn! Who's an idiot? It is definately me. I torqued it for the spec on a ARP 2000 7/16" bolt with a 7/16" head. Mine is an ARP 2000 3/8" bolt with a 7/16" head. I only looked at the head. that was dumb. It is supposed to be at 43 ft. lbs. Thanks for info.

Originally posted by EclipseDrivinDelt
whoa damn! Who's an idiot? It is definately me. I torqued it for the spec on a ARP 2000 7/16" bolt with a 7/16" head. Mine is an ARP 2000 3/8" bolt with a 7/16" head. I only looked at the head. that was dumb. It is supposed to be at 43 ft. lbs. Thanks for info.

Yes 43lbs it is... Hope you didn't do ay damage...