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Crank not rotating

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Oddjob:
Remove the gearbox, remove the camchain and primary chain and shaft. So just the crank is left in place. If it still won't rotate then maybe somehow you have bent the crank but I doubt it. As you tighten the bolts do each one a little, check the crank rotates after touching each bolt, keep doing that as you keep tightening the bolts, a little at a time. If the crank stops after tightening one specific bolt check the journals nearest to that bolt.

I'd also spin the crank with no bottom case on, see if you can spot anything wrong, like a bent end of the crankshaft.

McCabe-Thiele (Ted):
I think it very unlikely that you could have bent the Crank.
At the start of your strip down did it rotate freely?
If it did what is the range of the Crank case markings codes could you have confused number 1 cylinder with 4 it's easily done when stuff is upside down?
Plastigauge is where I would start now to identify the cause, Kens advice sounds a good starting point.

smoothoperator:
+1 on plastigauge measuring. Will let you know what your clearances are. Take your time, walk away from it for a while. When the plastigauge turns up, give it another go.

alexdecker:
Ok, did some extensive research this morning. I made several discoveries.

It turns out the crank seizes when I tighten down on a specific journal. My motor has the writing BCBCB on it. I am not sure about the color of the bearings though. But it seems to be one bearing in particular that makes the whole thing seize up.

Another thing I discovered is that the crank does not seem to rotate completely evenly throughout its motion. This is not visible to the naked eye, but when tightening down certain journals, I can feel the rotation taking more force throughout half the rotation. Not by a lot, but definitely noticeable. This could support a bent crank, but could maybe also just be the uneven tightening of the screws in this experiment?

Weird thing is that everything rotates freely and with no trouble before I took it apart. So something definitely happened along the way…

I am using allen head bolts with a washer, instead of the original bolts. Could that change anything in regards to the torque spec? When I torque the bolts down with my screwdriver, everything still rotates. But when torquing to spec, it seizes up on the on particular journal.

- Alex

Bryanj:
From what you are saying it would suggest a bent crank, many decades ago i worked on an accident damaged 500 where the tapered end had been bent in the accident, we actually managed to straighten it with a specialy made bar and it did many years service BUT the crank rotated free all the time, it was not out of the cases ever.
I am negotiating with an ebay seller who tells me he has 2 nos cranks, i would like one to go with the nos cases i have, i could ask for a price for both if you wish.

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