Replacing twin distributers with single for 3.6

[Cupcar]

Anyone done a swap of a 964/993 3.6 dual distributors for a single Marelli or Bosch capped unit and retained the stock DME, coil packs, etc?

Seems it could it could be done by just installing a single cap unit (but without any points or trigger system) and a hall sensor using the stock advance curve moving the rotor and the DME doing the rest.

Maybe the advance curve has to be changed a bit?

Am I missing something?

[Steve@Rennsport]

Originally Posted by Cupcar

Anyone done a swap of a 964/993 3.6 dual distributors for a single Marelli or Bosch capped unit and retained the stock DME, coil packs, etc?

Seems it could it could be done by just installing a single cap unit (but without any points or trigger system) and a hall sensor using the stock advance curve moving the rotor and the DME doing the rest.

Maybe the advance curve has to be changed a bit?

Am I missing something?

Thats tricky to do since there is no option for a Hall sensor, needed for knock sensor functionality. The magnetic trigger would not be used and the advance mechanism reconfigured strictly for rotor phasing.

All the ignition timing functions would be retained by the Motronic ECU, but its ability to advance/retard specific cylinders on demand would be compromised.

[Cupcar]

Originally Posted by Steve@Rennsport

Thats tricky to do since there is no option for a Hall sensor, needed for knock sensor functionality. The magnetic trigger would not be used and the advance mechanism reconfigured strictly for rotor phasing.

All the ignition timing functions would be retained by the Motronic ECU, but its ability to advance/retard specific cylinders on demand would be compromised.

I still wonder if a custom unit could be built using the drive shaft, phasing curve and Hall sensor from a 3.6 2 cap distributor?

Interesting on the Hall sensor, I thought it was to just show the DME where cylinder #1 is like the cam sensor in a Motec or other system does.

Just seems like a fun project, but probably too much work.

[Steve@Rennsport]

Originally Posted by Cupcar

I still wonder if a custom unit could be built using the drive shaft, phasing curve and Hall sensor from a 3.6 2 cap distributor?

Interesting on the Hall sensor, I thought it was to just show the DME where cylinder #1 is like the cam sensor in a Motec or other system does.

Just seems like a fun project, but probably too much work.

Anything is possible, given sufficient resources and this would a total custom unit,...

The hall sensor provides cylinder and camshaft reference for the knock sensors: the flywheel's 60-2 configuration provides crank reference & timing.

It wouldn't cheap to do, but it would be less maintenance-intensive than the OEM 3.6 dual distributor.

[Cupcar]

Doing a little homework, thanks to bazar01 on this forum, I found this picture and the phasing weights and Hall sensor come out as a complete unit after removing 3 screws.

The builders of twin plug distributors basically remove the corresponding set of parts from a stock SC distributor to build twin plug units for early cars.

It seems it could be done for the 3.6 just as easily, maybe with minimal modification to existing conversion parts.



Also, not to put too fine a point to it, but at least for the '89 C4, the factory "Information Technik" states about the "Double Ignition" on page 2-15:

"A hall sender, which is required for identification of cylinder no. 1 (ignition TDC) is installed in the double-ignition distributor. The hall signal is required in the DME control unit for assignment of both knock sensor signals as well as the control of sequential fuel injection.(my italics)

Each distributor rotor is guided by centrifugal weights depending on engine speed. This guarantees alignment between the distributor rotor and corresponding ignition contact in the distributor cover."

This seems a good product for someone to develop...Steve???

[Steve@Rennsport]

Originally Posted by Cupcar

The builders of twin plug distributors basically remove the corresponding set of parts from a stock SC distributor to build twin plug units for early cars.

Some do, others use either Mallory magnetic pickups or GM HEI components and employ ball bearings, like the OEM 3.6 dual-distributor or JBR ones have.

It seems it could be done for the 3.6 just as easily, maybe with minimal modification to existing conversion parts.

Its not that simple since one would be machining the shaft, making a custom distributor body, and hopefully installing ball bearings for durability. Given all this, I think its less expensive to buy a good twin-plug unit such as the JB Racing one if one wants the RSR look.

Most of our Motec-equipped engines receive either a twin-plug distributor of some kind, coil packs, or COP, depending on the budget. We use either the OEM 3.6 unit or a JBR one.

Cam position senders allows for sequential operation and for M600-equipped engines, we can retain knock-sensing for pump gas operation.

[Cupcar]

Well, the pipe is at least lit, the smoke going up and the pipe dream started.