Liquid locks (hydraulicing) in radials... you can never be too careful. Nine blades by hand in the normal direction of rotation on a DC3 to make sure it was OK to start. Only ever encountered a liquid lock when an engine hadn't been turned for a few days or more. No problem - remove lower plugs and move the prop until all the oil was out.
However... used to maintain an Antonov An2 (ASz 621R engine, a metricated version of the Cyclone) - turned the engine by hand as per normal for the first start of the day and attended to some other issue for ten or fifteen minutes. Jumped in, started up (inertia starter), engine fired and a couple of seconds later stopped dead with such force that I felt a wing lift (a lot of stored energy in that huge four-blade prop).
Sick feeling - took lower plugs out and watched a small stream of oil run from one cylinder. Never did find out the reason. Blown supercharger seal maybe... Replacement engines from Poland only cost about $2,500 then so it wasn't that great a tragedy.
Re starting techniques, I knew a very experienced DC3 pilot who started in rich as a matter of course (as opposed to ICO in the book) and there was always a smooth result.
Can't beat that lovely clanking, burbling radial idle.
