22-10-2022, 07:24 PM
The .002" camshaft endfloat is achieved by the lapping of the camshaft gear onto the camshaft or by facing the camshaft bush. If the camshaft now moves .004", either things have worn to increase the clearance between camshaft and bush or the bush is moving axially in the crankcase. This is a photograph of my square headed camshaft bolt which had worn the retaining hole in the bush oval and bent over due to the axial pressure on the camshaft. There are several threads on here about replacing this square headed bolt by drilling and tapping crankcase and bush 5/16" BSF and sealing with a Dowty seal. Whether or not this is the cause of your knocking I would suggest this is an easy and useful modification. Not necessarily any need for a new bush, just turn it through 120° and redrill both holes.