I wonder if anyone has had any experience of using a new Molnar crankcase for a road bike? I have always found them a good well designed and made item but I have only used them in a racing context. I noticed in passing that the dynamo housing that faced where the dynamo sits featured a flat face with a small annular recess rather than the large concave recess of the original Vincent castings. Has anyone found this causes any problems with an alton generator?
I have Molnar cases on the 1360 engine. They are excellent. I had no problem fitting the Alton.
The big bearing size is for the use of a crankshaft with oversized mainshafts. This can be done when building an engine designed for high rpm. The standard crank is good for 5500 rpm but not continously ( see Picador testing)
The crank in the 1360 uses 30 mm mainshafts whereas the standard crank has 1" mainshafts. The TP crank that I used is designed for up to 7000 rpm use. That matches well with the MK5 cams which hit max power at 6500 rpm.
The bearings that fit the 30mm shaft are 72 mm OD. Standard bearings are much smaller in OD.
The Molnar cases are greatly thickened in the main bearing area, so it's no problem to machine out for the big bearings. If you tried that with original cases there would be no material remaining to hold the 72mm od bearings.
I used bearings of a different configuration but the same spec and size as the Norton Commando Superblends that solved a big problem on the 750 Commando. The bearings are rated for 11,400 rpm.
Glen
