Re: 1956 Oliver 5.5 hp won’t start

[amuller]

It looks hard to say about the throttle cam without a good one to compare it with. Is there a witness mark on the cam corresponding to the beginning of throttle opening?

Not to be insultingly obvious, but is the flywheel key in place? Does it have a reasonable spark in both cylinders? Choke closing? Are the cylinders/plugs wetting with fuel mix?

I am not familiar with these motors, but the crankshaft seals might be an issue as suggested. Or the reed valves.

Carry on! You will get there.