You can´t have it all: I don´t see a chance to get the rocker out with 10 mm pushrods. But then why should I want just this without other jobs on the head ? Once the engine was assembled with care no periodic messing with components should be due.
What I get out of our discussions is that real soft stainless - meaning the chrome-nickel type with factor 16 extension is near to pointless as difference to plain carbon steel or any other tool steel is 2 thou while typical steel factor is 12. The ball end that sits in the adjuster screw is poorly lubricated , in my imagination, so no real stainless advisable to use here. So either you go for carbon/chrome steel with torch-hardened balls and live with a 10 grams penalty as compared to my 10mm alu rods. Or skip the idea of dropping pushrods through that thread and get tubes with hardened caps on these. The lightest design would be a 9-10 mm thinwalled steel tube, half a mm is allright, available from Aliexpress at low cost, and have hardened ball ends brazed on. Extremely safe for speeds your Vincent racer will never ever reach. But I want to have some more control over valve clearance with hot engine so alu tubing offers more options as to setting nil - or possibly some clearance with cold engine. Depends on road tests and noise checks with warming engine. I hate rattly engines, no matter if they are vintage, I´d feel embarrassed to show up with that sort of bikes. This sort of music is usually a telltale of a clapped out engine plus neglect. No, thanks, not my idea of classics when I can help it.
Yes, I believe many head nuts of studs on engines get overtorqued because with alu cylinders and heads heat growth with extra stress is not seen. That is why I warn from heaving on spanners on head jobs - not Vincent related only. You can compensate just a little by using chrome-nickel stainless long studs with MoS2 paste on head threads when assembling the lot. But don´t use excessive force , not helpful, not even for preventing leaks. I did standard M 10x1.5 studs in case adapters below and M 10x1 for head nuts, all rolled threads in chrome-nickel 1.4301.
Nice idea about 2CV alu pushrods, what sizes are these, i.d and o.d. ? I would not think 7075 or other alternatives were available in tubes ?? Yes, you can go thinwalled seen from the bending aspect , the Vincent rods are only 150 mm. But there is the load from valve gear components accelerations the alu tube has to carry. I haven´t got the brains to calculate all forces for telling what wall thickness you´d better keep to. Steel tubes with 0.5 mm wall would do allright - not my choice for heat growth compensation here.
Vic
