Dellortoman
Hero member
- Location
- Tasmania, Australia
I always set Ignitechs to 1 revolution before applying a spark just as a safeguard against hydraulic lock. You don't want one cylinder firing if another cylinder is coming up to compression with a gutful of fuel in it.
You could argue that 2 revs would be more cautious, because it takes each cylinder through its full cycle. But I figure one revolution is enough because if the "wet" cylinder is on the exhaust stroke it'll splutter fuel out of the open valves. If it's on the compression stroke and hydro-locks, the starter will just stall against the trapped liquid on the first cycle so won't get as far as 2 revs anyway. There will normally be some air above the liquid in the cylinder to cushion the lock, so hopefully it'll be a "soft" stall and won't damage anything. That should be enough of a clue to pull the plugs and give it a spin to blow the fuel out.
It never occurred to me that a rev or two without spark might make life easier on the starter mechanism. I just set the base advance to 0° at cranking revs so it's extremely unlikely to kick back against the starter gear when it fires.
You could argue that 2 revs would be more cautious, because it takes each cylinder through its full cycle. But I figure one revolution is enough because if the "wet" cylinder is on the exhaust stroke it'll splutter fuel out of the open valves. If it's on the compression stroke and hydro-locks, the starter will just stall against the trapped liquid on the first cycle so won't get as far as 2 revs anyway. There will normally be some air above the liquid in the cylinder to cushion the lock, so hopefully it'll be a "soft" stall and won't damage anything. That should be enough of a clue to pull the plugs and give it a spin to blow the fuel out.
It never occurred to me that a rev or two without spark might make life easier on the starter mechanism. I just set the base advance to 0° at cranking revs so it's extremely unlikely to kick back against the starter gear when it fires.
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