Crankshaft spacers for single cylinder engines

[paul.jameson]

I am assembling the engine for my 1936 LG250 and have available a wide selection of parts, including a complete LH250 engine. The LG250 engine went out on 26 Nov 1935 and the LH250 went out on 12 Oct 1935, the engine numbers being only 39 apart so the two engines are highly contemporary.

I decided to use the steel flywheel crank from the LH engine in the LG crankcases but made the discovery that the LG crankcases are too tight on the LH crank so it will not rotate freely and there is zero end float. The LG crank rotates freely in the LG crankcases.

According to the Parts Book, there is a bearing distance collar 0.180 wide next to the drive side flywheel but nothing equivalent on the timing side. Both engines have the 0.285 wide spacer between the drive side bearings as per the parts book.

On the LH crank the bearing distance collar on the drive side is 0.167 wide and there is an equivalent on the timing side 0.075 wide
On the LG crank the bearing distance collar on the drive side is 0.180 wide and there is an equivalent on the timing side 0.083 wide

The only spare bearing distance collar in my box of singles engine parts is 0.165 wide.

Has anyone else found such discrepancies between the parts book having a single bearing distance collar 0.180 wide and engines having a collar each side with the 0.180 collar not that thickness?

I think my problem with the LH crank could well be down to a big end bearing which is too long, there being about 20 thou more clearance between connecting rod and flywheel on this crank than there is on the LG crank and I can get over this by using the LG crank.

The biggest mystery is the bearing distance collars on the timing side which, according to the parts book, should not be there.

[nevhunter]

Have a Look at How well the Rod is centred and take that into account when you reduce the thickness of one side. I've often had a Bit More end float on the conrod than I would have liked. Nev

[Roger Gwynn]

Any spacers on the timing side are optional ones to shim the crank. The drive side has a distance collar of specified thickness plus optional shims. The original system was similar to modern cam shims in that one shim was exchanged for another of a different size rather than adding numerous thin shims. The distance piece thickness varies with the weather.