Rod Bearing ?'s

[ask0329]

Pretty sure I already know what to do and what the problem is but I like to hear it from the pros. Spun/tweaked the rod bearings on the rods for the #7 and 8cylinder. Picked up a set of new bearings and installed them all in every rod with the nuts just finger tight. Crank spun, all good so far. Started in the front torquing the bolts to 20lbs, 35lbs and lastly the recomended 45lbs and working my way back. I spun the crank each time to make sure all was working well. I make it to the back where the bad bearings where, put the bolts to 20lbs. The crank will turn and then it just stops. Stops at the same point everytime. I loosen the bolts and it spins no problem. Geez if I cant get it to spin at 20lbs it definately wont spin at 45lbs.

I'm thinking I need the rods checked by a machine shop and probably the cranked turned as well, as there is probably something out of round.

[parrot69777]

Going by what you said.....and without looking at it.....

I have never seen a bearing spin that the crankshaft or connecting rods didn't need to have some attention. Crank should have been mic'd and polished at the least....maybe ground or even replaced. Connecting rods need to be torqued and checked for size and or concentricity....maybe need recondtioned or replaced. You might even have swelled the rod a bit and the side to side clearance of the rod could be hanging it up.

[lovinlatemodels]

Check your bearings make sure they are in right. I know alot of people know this but some don't on H bearings there is a top and bottom bearing that will cause problems if you get them messed up.

[Milford Motorsports]

If you spun #7+8 rod bearings,it is almost a given that you have a spun main bearing also.Something stopped the oil from getting to those bearings.You definatly need to have the crank reground or polished and the rods checked,resized or replaced.

[ask0329]

One of the rod bolts on the rod with the blown bearing wore an obling hole in the rod and it was angled towards the other rod and cap. When torqued down it was binding against the other rod and cap. So I got that all apart, took the heads off to check the cylinder walls, pistons etc etc and all the pistons had some impressive marks on them from the valves. Way too big of a cam for the 400 sbc. So I'm thinking the valves whacking the pistons may of caused the bearing to fail. Trial and error. Going back to the 350 and getting that together and the 400 will go to the corner of the garage for the future.