Thank you Richard for your comments on the lubrication of the gears.
The arrangement I envisage will have 3 idlers, i.e. 1 between the crankshaft and the inlet camshaft and the remaining 2 would replace the current rollers that sit above the camshafts.
I intend to run these idlers on needle roller bearings mounted on fixed spindles, the outer ends of which will have an "outrigger plate" that supports their outer ends, (similar to the Vincent set-up).
The idler spindles would have an oil hole down the centre to feed oil to the needle rollers and this would be provided by an oil feed to each spindle, mounted in the timing cover and fed by a small jet in a line tee'd off the oil pipe returning the scavanged oil to the tank.
I believe that I am correct in saying that the oil pump scavanges oil from the camshaft cavity and not from the sump.
If this is the case and the timing cover is made oil tight, then possibly a hole could be made low down in the camshaft support plate to allow any oil building up in the timing cover to drain across into the camshaft cavity ready for returning to the tank. This drain hole would be below the crankshaft gear and therefore excessive oil drag would not be a problem and the gears would be lubricated by oil exiting from the idler needle rollers.
What do you think of this arrangement?
