Ariel Owners Motorcycle Club

Hi,Can someone tell me what this sleeve is for,I have just started to rebuild my Mk1 square,the crankcase was open for maybe 30 years so it was full of crud.I'm getting on O.K. but I came to clean up the camshaft and suddenly this ring came loose from the timing side,I have misplaced my Waller and the exploded diagrams and draganfly don't seem to list it! I haven't yet closed the crankcase halfs so not sure how much side play in the camshaft there is. It seems to have a step as if it locates in something thanks bill

The part is listed as a cam collar, part no. 1961-49 I think it's just a spacer to stop the end cam from rubbing on the crankcase.

The spacer is not listed in early parts books for some reason but it is fitted to all pushrod models and vital to ensure the cam lobes line up with the followers. The photo has it on the correct way round, with the smaller diameter next to the first cam lobe.