I do not have the luxury of a bench engine. During my last rebuild - as a temporary measure I fitted a piston WITHOUT any rings and I replaced the valve springs - both inners and outers - with just the 3rd inners from a lightning which are very soft. It was with this setup that I gathered my cam data and also used to set up my valve timing.Howard,
I don't think that will work. I mentioned that I have a bench engine. It is mismatched Comet cases with half a flywheel and main shaft so I can degree cams. I have very weak springs in the valves so it does not want to move much, but I think the stock intake spring will want to close and the exhaust spring will want to close also by resisting the cam ramp and it will want to reverse.
David
Once I was happy with the valve timing , off with the head and in with the proper piston with rings and then refit the proper valve springs. Yes it was a bit of work, but I believe, well worth it.
Martyn