The Stovebolt Site Forums The Shop Area Engine Shop 216 assembly problems

I just installed and shimmed new main bearings with a freshly turned crank and when I tightened them all down it wouldn't turn over. I loosened one at a time and when they were all loose it turns. Then I tightned them one at a time and it turned harder with each cap and when all were tight it wont turn. I used plasti gauge and clearance is .002 on all. I had everything clean and oiled, then I took it apart and used a thin layer of assembly lube, no difference. I have the new rear main seal in an I am sure that stiffens it up a little, but what gives?

Try tightening one main cap at a time, and see if one of them stiffens it up more than another. It's possible the alignment between the bores is off. Getting a block line bored is a pretty expensive proposition, but unless all the bearing bores are in alignment, it's possible to lock the crankshaft up even if indivual bearings each have the proper clearance. Also, be sure there is NO lube between the bearing shells and the block.
Jerry

Not trying to offend you, but are you sure the main caps and bearings are located properly?

Jerry, I did try tightening them one at a time, I can't single one out, it got a little harder to turn with each one. I had the crank shimmed with .10 under size bearings awhile back and it turned fine. Then when I sent the crank back to get the rod journals turned they turned the crank again by mistake.

I would try shimming them by the method in the manual. Once you have it right then could check the actual clearances.

What are you doing with the rods now that the journals have been turned?

I am having the rods machined out for bearing inserts. I can try shimming acording to the manual, but I just don't get what is wrong.

So, what's the main bearing size now? The logical assumption would be that they took it down to .020" undersize, if it was already 10 under. I would do a very careful measurement on the main journal diameter, and also measure the inside diameter of the bearings with the caps torqued, but the crank not installed. On occasion, I've seen bearings go out of round as they're torqued, usually due to a bad line bore. However, if it turned OK before the regrind, I'd insist that the machine shop correct their mistake, even if it meant buying you another crankshaft. Making a mistake and not correcting it is simply not an option for someone who is charging me for their work! Do you have another set of connecting rods sized to fit the new diameter of the rod journals?
Jerry

Drew, sorry I didn't see your post. I have them where they fit the best and that matches the part numbers front to back. Also there is some end play that was my first thought and I did smooth up the sides of the bearings that wrap around. And don't worry about insulting me.

Jerry, They are now .030 undersize. The story was they seen a scratch in one journal and were trying to take it down to .020 and went to .025 on one buy mistake, then had to go to .030 I really beleive they are a good shop just some bad luck for both of us. I also think the scratch came from there handling, more bad luck. I am getting the rods machined for inserts, (from a different shop). I think you have a good idea to measure.

On the race engines I build, we don't trust Plastigage at all. I decide what clearance I want, measure the bearing inside diameter, and tell my machinist exactly what diameter I want on the journals. That's a lot different than the normal way bearings are clearanced, but somebody who is building a $3,000.00 crankshaft from a solid billet of metal will do pretty much what the customer wants.

"Mistakes" like you're describing, plus the too-tight turning torque, would make me very reluctant to use that crankshaft. If you can find one that hasn't been butchered up by an incompetent machinist, I'd reccomend replacing that shaft. It's the backbone of the engine, and taking chances on it might doom your overhaul job to premature failure.
Jerry

I tried shimming by the method in the manual like Trucknix recomended and it now turns over with all tight. Then I checked with plasti gauge and the back and one inter were a little loose so I took out .002 and it still turned. One other thing I checked for was oil under the bearings and there was, maybe that was my main problem. I see were the plasti- gauge made a slight imperfection in the one of the new bearings. You have to be very carefull to have some clearance before using plasti- gauge. Thanks to all that helped me. (I needed to borrow a micrometer so thats why I didn't measure)

Tuley, there are 10- - - -count 'em- - - -216 crankshafts on ebay right now, already reground, and NO BIDS YET! I just might corner the market on stovebolt cranks if I can figure out how to ship that much weight without breaking the bank!
Jerry

Hi

I just finished my 216-- So assuming that you have the correct main bearing for crankshaft size, This is what you do:
Make sure that you have lot of .002 shims. Place two or three shims on each side of the rear bearing and tighten the bolts. What your looking for is a slight drag. If the crank is tight add another .002 shim to each side and repeat the last step. When you feel just a slight drag, loosen the bolts and place another .002 shim under each side and tighten. The crank should turn freely. Now for the IMPORTANT! step ----
Loosen the bolts that you just tightened. and do the same thing to the next bearing in line. This procedure can take a while but its not rocket science and If I can do it so can you. Once you finish all of the bearings you should be able to tighten all and the crank should move freely, especially if you do not have the connecting rods installed -- which they should not be when your doing this procedure.

Good Luck

Charlie2, I did exactly as you did but then I plasti-gauged and a couple bearings had between .003 and .004 clearance so I took a shim out of those. There is some drag but I don't know how much is too much so they don't burn up. I have the right bearings but I have to be honest and say they must have been for a later engine not requiring shimming because they were slightly too long to alow for bearing crush. You guys will cringe but I machined a little off so there was clearance and I figured if I took a little too much the button on the bottom of the bearing will hold it in place. I was feeling confident I had it shimmed right last weekend but after thinking all week I am wondering if it's too tight. In the manual it mentions without excessive drag but they are cranking with the engine in the truck and moving the pistons and valves. On the stand should it turn with no drag. Sorry to beat this to death but I want to know it's right. Thanks in advance.