Convert a 3.2 to dual plug with MSD 6a

[Bob Gruen]

Looking at the MSD 6a's owner's manual:

"Trigger Wires: White

This wire is used to connect to breaker points, electronic ignition amplifier output or to the Yellow wire of an MSD Timing Accessory. When this wire is used, the Magnetic Pickup connector is not used."


It would seem that the Motronic's wire to the coil could be rerouted to the white trigger wires of a pair of MSD 6as that in turn could drive a pair of coils and be used with a 3.6 dual distributor. Of course to get any real benefit out of it will require a dyno day and have the Motronic's ignition curve reshaped. Could it be this easy? am I misunderstanding something?

Bob

[Steve W]

No need to get so complicated, plus MSDs look out of place on a 911, can be failure prone, and are not inexpensive.

Best is to have the Motronic DME modified to trigger a single 993 ignition module, which then drives either a pair of Bosch 3.2/964 coils, or the 993 twin coil set. The 993 ignition module can be as inexpensive as $40 for non-Bosch, or up to $130 for Bosch. The entire setup will be as factory Porsche, very clean and stealth, factory reliable, and as inexpensive as you can do it. We've already done this installation on several twin-plug conversions and they run fantastic:

911Chips - 3.2 Motronic DME Twin-Plug conversion

[Geneman]

Steve W. can setupo this be used on a twin plug carbuerated motor ? I am not a fan of MSD boxes . This is on a 74 RSR race car. 3.0 liter. with 50mm PMOs.

[Steve W]

Theoretically it should work, but without the air flow meter, you lose part throttle ignition advance such as you would get from a vacuum advance for the low and mid rpm part throttle highway cruise fuel efficiency and throttle response, unless you figure out how to substitute a load sensor such as a TPS or MAP sensor for this. But since it's a race car that spends most of its time at full throttle, you probably don't care too much about that and could just leave it at a fixed value.