Twin plugging Motronic - Question

[Boxer 6]

I am planning on bumping my compression ratio to 10.3:1 on my 87 3.2 during this winters rebuild. I will be getting the heads twin plugged as well. What options do I have as far as the ignition goes utilizing the stock Motronic fuel injection. Thanks for the replies in advance.

[Steve@Rennsport]

Mark:

The easiest and least expensive route to twin-ignition on a Motronic-equipped 3.2 is to install a 3.6 dual-distributor & plug wire harness, an extra stock coil, and the Andial Motronic splitter.

You need to install the 3.6 distributor crank gear as well but thats cheap.

[cgarr]

Originally posted by Steve@Rennsport
You need to install the 3.6 distributor crank gear as well but thats cheap.

I didn't do that on mine, did I do something wrong?

[Steve@Rennsport]

Originally posted by cgarr
I didn't do that on mine, did I do something wrong?

You'll have more noise & backlash if you don't swap crank gears as these are matched parts. Its also possible that the brass crank gear might not last as long, too.

[cgarr]

Would you advise cracking it open for this or not? I have the time and the engine only has about 300 miles on it

[MBruns]

Steve, the 3.2-3.6 (84-98) are the same for both dist. drive gear and the brass crank gear so he will be fine part #'s 930 602 424 00 is the dist gear, 930 102 112 00 is the crank gear,

We are building 12 pin dist for 911 engines 2.0-3.8 and have done alot of research on this. we also have some custom dist gears made that will tightem up the back lash common with even the new gears installed. we are doing both internal trigger and crank triggered versions.

Mike Bruns JBRacing.com

[Boxer 6]

Sounds like the hardest part of this conversion will be locating the parts. Thanks!

[Steve@Rennsport]

Originally posted by Boxer 6
Sounds like the hardest part of this conversion will be locating the parts. Thanks!

Hi Mark:

I have a good 3.6 dizzy here and the Andial splitter if you need it.

A good used coil is easy to source.

[Steve W]

Mark, in addition be sure to have a chip designed for the twin plug ignition setup as a 93 octane performance chip for a single plug application would have way too much ignition timing for the motor.

[Henry Schmidt]

Andial splitter and the Supertec twin plug distributor.
Looks great, works better. We can build the twin plug distributor using your stock 3.2 Carrera distributor.

[Boxer 6]

Originally posted by Steve W
Mark, in addition be sure to have a chip designed for the twin plug ignition setup as a 93 octane performance chip for a single plug application would have way too much ignition timing for the motor.

Hi Steve,

That would mean I need to buy another chip from you Thanks for the advise

[Henry Schmidt]

Originally posted by MBruns

............... we also have some custom dist gears made that will tightem up the back lash common with even the new gears installed........

What back lash?

You only get back lash if you miss match the early dist gear (2.0-2.7) with the late crank gear (3.2-2.6).

[MBruns]

You are fortunate, and I know the difference in the gears early vs. late. we see the timing wiggle on most all of them some up to 5-6 deg visible on the dyno with a timing light.

check a few distributors installed with a dial indicator at the tip of the rotor, and I dont mean the advance mech. or set one up in a case half before assy.

Mike Bruns JBRacing.com

[Carrera3.5L]

Originally posted by Boxer 6
I am planning on bumping my compression ratio to 10.3:1 on my 87 3.2 during this winters rebuild. I will be getting the heads twin plugged as well. What options do I have as far as the ignition goes utilizing the stock Motronic fuel injection. Thanks for the replies in advance.

I've posted this before in other threads, but here is what I used for my conversion:

964/993 distributor (bought on ebay for $220, patience can be a virtue)
new dist. drive belt, vent kit, caps & rotors (so I had a maintenance baseline but you may not want/need to do this)

Andial signal splitter

2nd Bosch ignition coil (part number 944 602 115 00 or 00 055)

Custom fabricated alu bracket to hold both coils

Custom Magnecor wire set (just call them with wire lengths you require and they'll build to spec or simply make your own wire set)

2nd set of lower plugs (still use stock WR7DC)

Custom made nylon wire separators

Lower Plug hold-down clips (probably not necessary in most instances but looks nice)

Twin-plug heads & lower valve covers









The single distributor/cap/rotor looks clean as well, and maybe make it easier to pass a visual inspection for smog testing if needed? Although I haven't had a problem yet with the 964/993 distributor passing the visual either...

Figure on spending anywhere from $1,200 - $2,000 for the conversion pieces depending on how resourceful (or maybe lucky is a better term?) you are with parts availability/selection/negotiation...

One thing not mentioned and that you should know is that if using the 964/993 distributor with the stock heater blower tube, it will most likely interfere and you will have to "modify" the plastic tube to fit...in my case it was a non-issue...

Ralph

[WydRyd]

Originally posted by Henry Schmidt
Andial splitter and the Supertec twin plug distributor.
Looks great, works better. We can build the twin plug distributor using your stock 3.2 Carrera distributor.

Henry, how much is this/your conversion?

I need to hook up my twin plugged heads too, but it seems my intercooler piping will interfere with the 964/993 distributor, so I need a more "compact" solution.

[Boxer 6]

Originally posted by WydRyd
Henry, how much is this/your conversion?

I need to hook up my twin plugged heads too, but it seems my intercooler piping will interfere with the 964/993 distributor, so I need a more "compact" solution.

I have the same question. I have seen the price of the cap and rotor