Thanks for the explanation. So, if I understand correctly, you are using the stronger springs to help force the valves closed in order to get compression. Question: once you have run-in the engine, fully seating the valves, would there be any advantage to going back to softer springs? I don't know enough to know what the impact is, but wondered if the heavy springs would leach some power from the engine - ??Combustion chamber hasn't changed at all, other than the location of the valves and sparkplug. Biggest change of all was the shape of the rocker arms. They went from simple "straight' pieces of steel with rollers on the center to the new ones with the cantilevered rollers at the end. In test mode, with the adapter screwed into the sparkplug hole, the cylinders sealed up tight up to 50 psi. of air pressure No leakage of air out the exhaust pipe nor out of the carburetor throat, nor past the rings. The valves sealed great under "test" conditions, but engine had no (or very little) compression when cranked over. Nothing gets past the Viton o-rings, no leaky head gasket. Conclusion is that the valves aren't seating properly. They are lapped, and do seal under "test" conditions but not in normal "start the engine" mode. Normally, if I can get an engine to fire at all, the force from igniting fuel will force the steel valves against the brass seats hard enough to make a perfect seal. Tried to start it already, and there simply wasn't enough compression for the fuel to ignite. It's rather coincidental that Boomer has been talking about valve springs.--That is where I ended up going anyways as that's about the only thing left to try. Ignition and valve timing hasn't changed since the last time I had the engine running. I can push the valve off the seat, against the new spring pressure when gripping the head between my thumb and finger. It is noticeably harder to do that now, but my cams, lifters, and rollers on the rocker arms are all heat treated 01 steel. I did have to make a spring compressor, because it is very finicky work trying to get the spring compressed, the keeper in the right spot, and the c-clip on without something to compress the spring and let me work with both hands. The push-rods are 1/8" diameter about halfway up their length, then are reduced to 1/16". I will probably make new pushrods tomorrow that are 1/8" diameter over the full length. I use .031" thick waterpump gasket for my head gaskets. I have never had a head gasket burn or "blow out".
I was thinking more in terms of when the intake closes. That would be part of the cam lobe duration.I found exactly what I had set it for. Both exhaust and intake lead by about 20 degrees.