Topic: PO over torqued /crank bolt

[evopgt]

Hey all. Bit of a pickle here. The PO on my 77 750A project must have overtorqued the crank bolt in the points plate. The bolt is gone, I removed the points plate and spark advance plate which also has a crack on it right by the peg that goes into the crank. ( see pics). The small hole that the peg mates into on the crankshaft looks a bit out of round from whatever he did. My? Is, Will this distortion on the hole in the crankshaft cause a problem? Can I just get a new spark advance set up , or does this mean the crank would need to go? I was hoping to get it fired up and see how it runs but now this.

[Tracksnblades1]

🤔 Are you sure this wasn't caused by using a big crescent wrench on the advancer's nut to turn the engine over with the sparkplugs in it. Relying only on  that Indy bittly pin to turn the crankshaft by itself and do all that work...😩

Bryan J and others know the advance rates of all the different advancers. When you buy a good one. 😇

Check and see how bad the stud is bent also. A straight one makes for a simpler tune up.

[PeWe]

If the stud is straight and advancer tightened the case mark can.get a good alternative mark wirh help of a piston stop and degree wheel.
Rockers removed so valves will not lift and bent by the piston stop when verifying the real TDC of 1 or 4. Double check doing 2:3 too.
Maybe possible using a screwdriver to be dipped down at the guessed position, only remove plugs. 
Rotate crank just a little and see if screwdriver will move up or down. At TDC it will not move during a few degrees.

[69cb750]

Replace damaged parts, crank probably ok.

[evopgt]

Thanks guys.

[bryanj]

Replace stud(dont forget the O ring) fit advancer pin carefully into hole and see how much play there is then maybe shim the pin to fit properly. New big and small nut tightened to spec then DO NOT turn the crank with a spanner on either of those nuts, remove the generator cover and use the bolt under there!

[PeWe]

Possible to use kick starter to rotate the crank.