Hi all. BSA A65 1971 OIF motor. I have had the timing side bush replaced (0.020 under.)The crank was ground to suit and the bush honed giving 1 thou or so clearance. I have fitted the early type due to ignorance on my part. The flange is thicker ,thus making the setting of the endfloat different. Can i wriggle out of this or fit the correct bush.? I would also like some advice on finding a left hand or set of used crankcases. Cheers, Max.
You’d be batter finding a matched set of cases as they were Machined as a pair from the factory. You could fit another left half but the machining costs to have them match up wouldn’t be worth it.
Also, too late now but if/when you have another crank ground. They should grind the crank back to round then size the bush to suit. That way you end up with a crank that lasts you a lot longer.
You also want to get hold of the correct bush with thrust washer.
If it's a genuine bush, it will have a plated insert, similar to big end shells, so they can't really be resized.
I don't have much experience with the timing side bushes for the early ball bearing crankshafts, but it can probably be machined to the same thickness as the later bush, which will allow the use of the thrust washer.
I agree with Allan about going for a matched pair of cases instead of just the drive side. Unless you have a mill and lathe, there will be quite a bit of expensive work to get a mismatched pair of cases to work together.
I would get the flange milled to size on a milling table, if is a good setup and main driveside bearing and bush are inline I would not want to disturb them.
Factory "matching" cases can sometimes be problematic
Last A65 case I had here in for boring of the crank bushing was out more than .020"+ once set up on the table
Both bores (bearing and bushing journal) where in line, however where skewed once indicated off the case halves
If the flange is the issue and the bushing is fitted, I would mill the flange