allowing the field to build up, then the second set open causing the spar=
k
and the first set then close again before them extending the dwell time.
According to the trigonometry in this sheet a single set of points would =
be
closed for only 22.5 degrees, whereas using the twin points a dwell angle=
of
36 degrees is obtained, this is achieved by the 22.5 degree closure of ea=
ch
set with a 9 degree overlap where the spark occurs.<
Your description makes sense. I believe that's the same reasoning used f=
or
dual point distributors on High Perf race engines, but most "newer" dual
point distributors have the position between the point sets fixed so that=
this overlap is built in and not adjustable. Then all you have to worry
about is point gap, overall dwell time, and timing. =
I can see that if this distributor is buried behind the fan and between t=
he
belt that accurately setting this on the move would be impossible. My Fo=
rd
9N tractor with a 4cyl flathead engine has a similar configuration, the
distributor is driven off the front of the camshaft. Fortunately the
timing is fixed and since it tops out at about 2000 rpm a simple setting =
of
the point gap is all that is required. =
So do all old Ford flathead V8s use the same front mounted distributor
configuration with dual points? =
Thanks for the info.
Dave
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