On Fri, 25 Jul 2008 19:44:17 -0700, Don Bruder wrote:
In article ,
"Bill" wrote:
Good plan - Called "variable timing", and used on the Model T, for
exactly the same purpose/reason, if I recall rightly. But I'll be dipped
if I can tell you what the exact mechanism was.
Retard the ignition timing by rotating the distributor?
Model T's used a buzzerbox to generate high voltage, so I don't know their
mechanism exactly.



But it's just plain NOT going to happen by putting something between the
plug and the wire - It's something that has to be done at a "lower
level".
No, the location where the crank angle is detected (ie: where the points
live or where there's a magneto) would have to be turned.

Most "lawn-mower type" engines fire by way of a coil (or two coils, in
the case of a two-cylinder rig) bolted solidly to the block (which means
no adjusting of spark advance/retard is possible without major surgery)
with a magnet in the flywheel passing under it. And since the flywheel
is almost invariably keyed onto the crankshaft to maintain timing,
that's also almost impossible to alter without major surgery.
A fixed coil with a magnet on the flywheel would be difficult to modify.
Maybe the flywheel or coil has shifted?


Adjusting spark timing is dead-simple on a car, or other distributor-fed
engine, since all it takes is twisting the distributor a bit. Doing it
on a coil-and-magnet rig like most small engines is nearly impossible
unless the capability was designed in right from the start.

Maybe it's experiencing pre-ignition or incredibly late ignition. Replacing the
sparkplug might be a good start.