Saturday, 23 September 2023

FH - Engine bottom end

 While the painted parts are away, I've got the engine on the bench. Way back when I established the state of the bores, mains and big ends and what I want to do now is to trial fit the new large bearing crank into the original cases.

A little while in the kitchen at home saw the main bearings fitted:




It's then no more than an hour's work to assemble the crankshaft and the timing gear; the good news is that the timing gear bushes already in this case are on very good condition with very little play. Shame I already bought a new set.

It was clear that the crankshaft was a bit tight. The setup with the DTI reveals no end float and the crankshaft was mildly stiff to turn, but then it does have a large plain bush at one end:


Investigation revealed that the drive side bearing wasn't fitted fully home against the crankshaft web. With that fixed, we have 0.34 mm end float:

That's about 0.013"; we want a maximum of 0.005", according to BSA Service Sheet 208 - Waller is silent on the subject. Since 0.005" is 0.13 mm, we need to shim 0.21 mm; I've bought 0.25 mm shims which should give us 0.09 mm end float, or 0.003".

More later when bits arrive.

No comments:

Post a Comment