964 Distributor conversion for 3.2 engine
 

Can anyone tell me what is involved in adapting a 964 distributor to use with a twin-plug 3.2/3.4 ?

Thanks
David

You will need to get an ANDIAL splitter to fire the two coils and a reprogrammed chip with approx. 10 degrees or so less total advance in it. If you do a search, there has been some talk about making your own splitter as the andial one is around 600 or so the last time I checked.

Jeff

O.K let me add some more information. I currently am running Electromotive crankfire with PMO webers on a dedicated track engine. I want to throw away the Electromotive and go to a distributor setup. What all will I need ?

Thanks
David

There are 3 basic ways of converting a single ignition 911 to twin ignition, with a distributor, with an electronic crank-fired setup, or a combination of both.

Distributor : There are 3 options,

1: Find a used twin plug distributor. These come for sale from time to time, but are very expensive. They come in both RSR and 935 versions, don't buy a 935 distributor, as they have no mechanical advance, and would only run well at high RPM. I saw a 935 distributor for sale at a recent swap meet for $2000 with cap/rotor/wires. The seller reported it had been installed on a N/A MFI 2.8L race engine, and it ran good, but was really hard to start.

2: Convert a single plug distributor to take a 12 point cap and rotor. Andial does this conversion, it is also expensive, and the Bosch cap and rotor are VERY expensive ($1000+).

3: Convert a 964 dual distributor. Rennsport does this, as do a few others. I don't know about the others, but Steve Weiner at Rennsport installs the trigger from a SC distributor, and uses standard 964 tune-up parts. It will not fit on a turbo engine. I saw a 964 distributor with wires at a swap meet recently for $250, and the conversion is ~$400 IIRC.

All distributor options need a second CDI unit and coil, and the necessary wiring. Depending on which engine, and which distributor you are using, you may need to change the distributor drive gear on the crank, to make sure it spins the correct way.

Crank fired : Electronic twin plug solutions can be anything from full engine management systems, to the more economical Electromotive. There are a number of crank fired ignition systems from companies that have traditionally catered to the domestic Hot Rod market that can probably be adapted to a flat 6, like MSD, or Accel. There are also a number of crank fired ignitions on existing cars that may be adaptable by a resourceful do-it-yourselfer. An off-the-shelf electromotive unit costs ~$1600, Junkyard solutions will be less of course, but you will be on your own.

Combination units: This primarily applies to 84-89 3.2L engines, which use a electronic ignition with a distributor. On these engines, all the timing advance is controlled by the DME, rather than in the distributor. The 964 uses a similar system but with twin plugs. Andial makes a splitter to convert the stock DME output to drive 2 coils and a stock 964 distributor. It may also be possible to use a off the shelf timing control box, like the MSD Programmable Timing Computer to drive a 964 distributor on a non DME car, but like the junkyard crankfired solutions, you would be largely on your own.

In all cases, you will need to have the heads machined to add the lower spark plug holes. You will need to modify the lower valve covers to route the plug wires through, as well as the right side chain box to make room for the # 4 lower plug wire. This should add ~$400 to a standard top-end job machine work.

You will need to modify the engine tin to route plug wires. You will need to change one head nut on the bottom of each cylinder, the barrel nuts are too fat and prevent the plug wrench from fitting over the plug. You may need to modify the heater ducting on the left side to clear the new fatter distributor.

If I am overlooking something, speak up.

Tom