>Patrick J. Horne
> When a distributor cam goes around it opens and closes a set of points.
> Dwell is the expression of how much time the points are closed, expressed
> in degrees of rotation of the crankshaft.
>
> Points need to be closed for enough time to build up the magnetic field
> in the coil so that when it colapses (points open) a large enough voltage
> spike is generated, which is routed to the spark plugs.
>
> Not enough dwell produces a weak spark. Too much dwell overheats the
> ignition coil.
Can't say for certain, but since the dwell value is probably set within the
Pertronix modules, about the only thing you do if you move the pickup in a
circular direction around the distributor cam is to alter the timing,
although I'm sure changing the air gap may introduce some interesting
changes of its own.
That's why your timing changes as the rubbing block on points wears. That
wear changes the closing and opening positions rotationally and moves the
timing. That's why you always set the dwell before setting the timing.
FWIW, Ron
The ACL Group
Arlington, Texas
(817) 572-0873
ronday@home.com
ronnie_day@acd.org
|