Dual Point Distributor Complete For Sale

53hud54

Part # IAT 4203A complete with points,cond.,and vacuum advance,looks barely used,no wear on drive shaft.Listed for 4B,5B,6B,7B,4C,5C,7C,4D,5D,6D,7D. Would like $125 or best offer.

duncan

I am wondering what the difference in performance between a dual point dist and a single point dist.  Ray

53hud54

I was wondering myself,the only thing I ever heard was they where better for the Twin-H.Maybe someone who really knows will chime in

Glowplug

Overlapping time for points extends the time the coil can charge.  Stronger spark results

53hud54

Thanks,Oldfarmer,figured you'd be in there.By the way I found a Riviera hubcap.

duncan

Do you need a special coil to go with the dual point dist.  Ray

junkcarfann

There is another reason for aftermarket dual point distributors back in the day.

It was to allow the most timing advance possible without the engine pinging in higher gears, and thus blowing a hole in a piston.

It worked like this:

Using a 4 speed standard shift car as an example, the first set of points was in use only with the first 3 gears. That set of points was adjusted advanced enough to not ping in the first three gears, but to ping in fourth. 

Remember that the two points could be adjusted to open and close at different advance/retard times.

Then, when the car was shifted into fourth gear, a Double pole Double throw electrical switch on the shift likage disconnected the first set of points, and simultaneously connected the second set of points.

The second set was adjusted so it was in a slightly retarded timing position compared to the first set. Thus the car could have maximum timing advance in the lower gears for the most power, but less in the top gear where it is more likely to ping.

This is because the taller the gear, the less mechanical advantage the engine has, and the more apt it is to ping.

When I worked as a lad in a speed shop back in the 60's, most of the sales of dual point distributors were to 1/4 mile drag racers and circle track racers who used it for the purpose mentioned, rather than for getting a hotter spark with one advance curve. At least that is what they said when I asked why dual points.

ps...nowadays with computer controls, the computer takes care of all of that.

duncan

Will this dist work for everyday use Ray

RichardD

Points last twice as long. Can use slightly wider gap. Gap points the same (or dwell--each-- by putting thin cardboard between other points); then check total dwell.
Ken, what is the number and brand of the points you like?

53hud54

Richard,I have had best luck with Standard Blue Streak

RichardD

I have always used the ventilated points with the lubricating felt.