Rebuilding the 2056, To tight? Options

[72914S]

Well I finally got all the pieces for the rebuild.Yesterday Joe(Redneck Racer) came over,we planed to check the deck height.We put the crank in(those bearing pins are hard to line up).The rear main seemed real tight,finally got the dowel pin right and the crank turns freely.For the mock up I put the other case half on and tighted it up,now the crank won`t turn at all.Joe thinks I need line boreing.Let me say that this engine spun the rear main and cooked # 3 piston.Anyone out there have any thoughts. Am I doing something wrong.

[Katmanken]

Bearing bores don't usually get smaller. My guess is the rear main where you spun the bearing. One of two things could have happened, the bore got larger (wear) , or the heat from the spinning bearing galled (spin weld) the aluminum bearing seat. If it galed, the amuminum filled up the tolerance between the outside of the bearing and the bearing seat. Yup, the clearance isnt much, but it can make a heck of a difference.

In this case, a picture of the spun bearing seat may explain much. I have a small flat honing stone that I lightly block or rub across the inner machined surfaces of the case to locate swelled areas near the bolt through holes. The high spots show up. You might use the same process to see if you have a high spot or ridge in the spun bearing seat. That would be your problem. If you do, blocking and sanding is NOT a solution, a proper align bore and oversize bearings are.

Ken