Getting no love from the thread i started,, so trying here.. Turned over fine then I replaced the cam and rockers. Now same problem as others describe, struggles to get by compression stroke, impossible to pull start. Not enough to start it. Spring is right, ball is functioning when I manually operate lever, valve lash a perfect. 006, timing is right (unless it can mechanically be 180 degrees off? I don't think it can, TDC is TDC and compression versus exhaust stroke is dictated by cam placement, right?). I'm stumped. Put 60 lbs of air pressure to the cylinder and zip tied the decomp lever to the pin to keep the ball engaged outward and tried to turn it over by hand and something weird happens. When exhaust lobe is on the flat of the cam, just BEFORE the decompression ball bearing passes under the rocker, I can hear air escaping the exhaust. Valve should be closed at that point, right?! As I try to turn motor over by hand from that same point by turning the drive clutch CCW, I can't, but the air stops coming out of the exhaust as I try just as the ball disappears under the rocker. It's as if the ball is closing the exhaust valves?!? Bizarre. I can turn it over by hand with air to the cylinder at all other points in the 4 piston cycles and can hear the valves opening and closing, so it's not the compressed air that is preventing me from turning it over. Took rockers off and verified valves are seated and undamaged. Turns over fine with no spark plug, so no mechanical impediments. Pulling my hair out. Maybe I'm misunderstanding how the decomp works? I thought spring, although weak by design (no I did not prewind past the 1/4 inch called for) was enough to keep it against the pin when starting, so the ball protrudes out and hits the exhaust rocker to open the exhaust valves a hair when cranking starter. Then after at least few hundred RPMS when it starts, centrifugal force on the lever weight keeps the arm open so the ball cannot engage. Is that right? If it all didn't work perfectly before I replaced the cam I'd suspect the starter, or maybe a stretched timing chain is preventing the ball from hitting the rocker on time when it needs to. Tried a jump start too with my truck, so it's not the battery. HELP!! lol