Roy, as for me, I did not just get all new parts to complete lots of boxes of semi-scrap Argentinian B-Raps for finally have two fresh HRDs on the road after maybe 50 years in bits somewhere in the pampas. Instead it is a matter of checking all there is for defects and decide on repairs, fabricate new - or pay what suppliers are asking for. I tried best as I can to get around the last option, reasons the prices and more so my non-existent faith about acceptable products matching my expectations. So it is often my way to repair to my standards and fits than to pay for substandard.
When building an engine all parts require extensive checks of dimensions or damage. So in the end there should not be breakdowns from suspect parts and in consequence I do not especially prepare for easy roadside repairs like some here want to do and hold them from applying Loctite on clutch nuts and all. This brings up pictures from the fifties or sixties in me - well, photos. Born in 1953 I was too young to know and conditions in UK or Germany then were quite different. But in 2022 roadside repairs to be expected any day - really ?
You are not the same lot like the grey hair motorbike racers going to race courses with defective bikes and spend one day or two just to get the thing running - somehow, almost, for having 10 or 20 paddock parades at max. noise ?? Not surprising as the thing was never really fixed , sat in same place unrepaired for one year till next time - same joy . . .
Thinking about valve clearance hot or cold, in an all alu engine steel pushrods are not easily logic I´d think. Effects of heat in valves onto valve clearances appear to be less than expected when you look up clearances of , say, BMW 2 valve , maybe only 0.10-0.15 mm more for the exhaust which operates red hot. My view is the valve tulip gets red hot and increase in diameter . So it sits lower into the combustion chamber on its taper seat then, compensates a bit with the not so hot longer shaft. When looking at Vincents with all nil at cold and exhaust allright in hot condition it means cylinder plus head will have grown longer by a lot so the intake valve will be quite sloppy and noisy then. No way can you do anything with steel rods , no empirical preload in cold condition neither. You´d have no compression when kickstarting possibly and at least grind marks on follower faces from exactly same position on base circle grinding across the follower face. This shallow groove across the follower spoils the contact face with time with more grief to come.
With roller followers you want some light preload on them all the time for preventing slippage of rollers on oil so they stay nice much longer than get stuck for unknown times.
What´s to learn from discussions here: Try your best to keep valve clearance in hot condition close to nil , test with running engine and listen closely, some ticker is allright but noisy means components have a very rough life and a shorter one than necessary. Quieting ramps on traditional cams and more than 0.20 mm running valve clearance miss the follower which bashes the cam at the steeper acceleration curve - with excesssive loads into valve gear and the clatter.
With alu rods you may end up with some play in cold engine for having some ticker in hot engine to play safe and no burnt valves . My guess: Alu rods clearance nil in cold will be allright in hot engine as well.
Some years ago I did a 460 cc mod for a Horex single, new alu cylinder, alu head standard. Alu pushrods certainly and nil with cold engine. Alu pushrods are 280mm long - a lot, but in hot engine I´d want material with more heat extension than alu, with decent strength - but I cannot think of anything useful there, so it will remain as is. Else I´d have to do a roller follower mod for setting light preload at cold condition - ahh, no, not next time soon .
Vic