Stan Galat posted:Art posted:Ok, so for dual plugs, you have 2 coils, but only 1 albeit, 8 wire distributor? That confuses me. but I guess it is just one continuous circle of fire? And the advantages are smoother firing points? And what are differences for the plugs?
I tried to encourage ALB to enlighten me.
As far as I know, I’ve got the only twin-plug set-up on the forum.
There are several different reasons to do this, but the mechanics of it are as follows:
Under that cap Is a rotor that has two sets of points. The cap itself has two wires going to two plugs in each cylinder. The timing event is simultaneous (or nearly that way depending on who’s theory you ascribe to).
Something triggers each coil individually. I think in Wilhoit’s case, he uses two sets of contacts, I use a single electronic module that feeds the signal to a CB Performance Black Box modified with two coil drivers.
Each coil individually sends spark to the rotor (which remember has two sets of contacts). The rotor then distributes two sparks to two different plug wires on the 8-wire cap.
Firing a twin-spark set-up is easily 75% of the challenge. Using crank-fire and coil-packs is much easier and cleaner, but one loses the old-school look of a bundle of snakes under the deck-lid. There’s probably only a handful of people who will ever who care about this.
I am one of them.
There's an easy way to sneak two electronic modules into a slightly modified distributor too. We did it years ago in Soob and Corvair " airplane " engines. Yank out the points and it's mounting plate and install a new "points plate" that will hold two modules 180 degrees apart. We used Mitsubishi modules because of their small size. Grind off the cam lobes on the dizzy shaft and press on a suitable reluctor and you're about done.
Here's a picture of one I did for a Corvair which has a huge roomy distributor. The pic shows a small four cylinder reluctor and I needed a six cylinder one so that got pinched from a Ford distributor and got turned down just a bit and pressed onto the Corvair dizzy shaft. It worked fine. Some guys even went with one set of points firing 180 degrees across from an electronic module so you can have your cake and eat it too. If you didn't have twin plug heads, you could join both sparks with an MSD pn 8210 and fire two sparks into one plug.
