Twin-plugging on the cheap

[Tyson Schmidt]

I'm aware of Randy Jones' twin-plug method of using SC distributor guts in a 964 twin-plug distributor, with a splitter triggering two MSD boxes. (very klever)

However if you have an earlier car, you can't use SC guts due to the reverse rotation of the SC distributors. That would give you a retarding distributor instead of an advancing one.

So short of a teardown to replace the distributor drive gear on the crank, what can one do to utilize the 964 dizzy in an early motor?

Any bright ideas?

Use the setup but lock out the mechanical advance and use one of MSD's latest and greatest computer controlled timing computers.
Go to the MSD web site and they should have something.
Used a simulare setup on my Super Pro nova with a crank triggered ignition.
You should be able to get the advance profile from a manual and program in the same rate.
Just a thought.
Chris

[Tyson Schmidt]

Thanks Chris. That's exactly what I was looking for.

[Early_S_Man]

Tyson,

What is the approximate cost of a donor 964 distributor?

Since I haven't had either an SC or 964 distributor apart, and certainly don't have the dimensions ... all of the following is just based on 'eyeball' phisical appearances and supposition, and there may be conflicts of a mechanical interference nature that might prevent it from working, or at least not without some maching/welding , and/or fabrication ... but, it seems to me that a 169/184-series distributor is needed to supply a donor gear for the early engines' application, and if a point plate and 'guts' can be fitted inside, an SC distributor may not be needed at all, as long as the 3-pin Bosch CDI-unit or Perma-Tune box is used in pairs to provide a spark to the twin heads of the 964 distributor!

Supposition 1. The SC distributor seems to be a composite structure based upon a 'body' of the same diameter as earlier 169/184-series distributors, with an outer ring assembly slid around the body and anchored, and containing ONLY the magnetic pickup coil and seat and retaining mechanism for the larger SC distributor cap. The internal 'height' of the SC distributor may be slightly greater than the 169/184-series distributors.

Supposition 2. Since you say the 'guts' of the SC distributor apparently can be fitted inside a 964 distributor ... the 'guts' of a 169/184-series distributor ought to fit inside a 964 distributor as well. Additional machine work will be needed to locate and anchor the point plate support tabs to the 964 distributor body. Also. a cut will need to be made for the feedthru connector from the points to connect to the cable to the CDI-units.

Supposition 3. The single set of points can trigger two CDI-units simultaneously without any problem with a 'bridged' connection to both units' input leads.

Feel free to poke holes in the idea!