Posted by Brian in Oregon on October 15, 2000 at 03:11:22:
In Reply to: '63 Poly 318 w/Dual Point Distributor - Good or bad? posted by vince on October 15, 2000 at 02:49:00:
The purpose of a dual point distributer is to give more dwell to the timing. In other words, the points overlap their closed time, giving a longer time period (longer dwell) for voltage to saturate the coil before it discharges.
For the most part, electronic ignition made the dual point distributor and magneto obsolete.
However, I don't care for electronic ignition, and prefer a dual point distributor. Most dual point distributors have no vacuum advance, being centrifugally advanced. This means they are usually not the best choice for fuel economy, whereas a vacuum advance helps in this respect.
To properly adjust a dual point, you need to disconnect the 2nd set of points and set your initial timing with the primary points. Then you adust your final setting with the 2nd set. My old Accel dual point distributor has an external wire that has a diconnect on it to isolate the 2nd set of points.
I don't recall what my settings were on my 69 Cobra. I scratched them into the underside of the hood, and the car has been in storage now for long time. You'd think simple things like that would not be forgotten, but I guess middle age is catching up to me.