Yes, an old radial engine like most piston a/c engines was much easier to start when cold. You can and I have, hand proped a cool engine but no way can you do it when hot. Quiet safe really as she started to splutter and bang and turn you were well out of the way before the next blade followed through.
When cold, we used to turn the PW 1830 engine by hand, at least 6 revolutions to check for a hydraulic lock. 1st revolution was a gentle turn in case you had what you were looking for, I.E. Then prime with hand pump to gain fuel pressure. Unlock hand primer and give it 5 shots if IIRC and about 5 pumps on the throttle. Engage starter motor, inertial, when you had 4 blades past, ignition to both. When she began to wease, pop, fire and belch smoke everywhere, it was a case of pumping/controlling throttle with one hand and priming with the other until the engine began to turn over evenly, then lock up the primer.
When hot, it was just a matter of pumping up the fuel pressure, one or two pumps on the throttle, engage starter and once turning ignition to both.
It was important that you did not over prime the engine as it could cause a fire on start up. If you saw flames or someone saw them on the ground the important thing was to keep the engine running or turning.
This was from 30 years ago so my memory may have faded a bit.
Last edited by justlooking_tks; 22nd May 2008 at 04:22.