bosch twin plug rotor? - Page 2

Tim Walsh · Tim Walsh's Garage

RS I'd think there would have to be a way to do that. (ponders and stares at manual)

jmz · jmz's Garage

what about using those c2 distributors? they are available and can be made to work w/ the early cars

cstreit · cstreit's Garage

JMZ, This is true, but an option that costs in the range of $2000 between the donor parts, machine work, etc... Plus those distributors then must be recurved, and I assume the brass gear on the end is different for many 911's.

Steve Weiner makes this using MSD's, i Systems does this with permatunes. (these guys are new I think).

I would much prefer the single distributor setup, as it's more period correct ... The key would be to create something that could fit on a STOCK distributor. If you could obtain originals you could probably make them out of ABS or something non-conductive that would also be more durable?

cstreit · cstreit's Garage

MSD is making distributors for other cars, maybe someone could convince them to build one for dual MSD's on a 911...

cstreit · cstreit's Garage

Okay, so beer #3 has me thinking...

If you could find a way to modify a rotor so it wouldn't require a sprk to jump to the distributor cap, you could apply a relatively low voltage to the coil input, then use the spark outputs as a trigger for a set of coil packs.

THe only issue I see here is that the rotor to distributor cap connection would most likely be unstable. I'm just trying to find a way to eliminate electronics from the equation beyond what the factory has designed. I'm not having a heckuva lot of luck with switched and transistored electrons lately.

rs911t · 03-25-2003, 07:02 PM

Chris, I haven't had any beer, but here goes...

How's this for a analogy: a timing light. Start with the stock dizzy setup (call it the Primary) and trigger the Secondary set of plugs by attaching an induction pickup to each respective wire in the Primary? In effect you have a distributed distributor (this is making me dizzy (sorry, I had to say that!

)).

No modifications to the Primary ignition. Simply slave the Secondary with a set of inductive pickups.

Got the picture? Now, go for beer #4 and run with it!

cstreit · cstreit's Garage

Yeesh greg... Interesting idea... I would wonder if the signal from an inductive pickup would be enough to trigger a coil reliably...

Cool thought, the lower plugs could be a coil-on-plug setup even...

Tim Walsh · Tim Walsh's Garage

you could probably use the inductive pickup to run a transistor that outputs to a coil?

cstreit · cstreit's Garage

Tim, Good idea, but in this case I'm trying to come up with a transistor free solution based on my personal experiences with new and improved ignition systems that are not so positive.

CamB · CamB's Garage

Theoretically you aren't offering much that Chris' problematic setup has. You are back to coil packs. Triggering could be from the crank or you could convert a dizzy.

Coil packs are never going to look period correct though.

Does it really cost $2k to get a 964 dizzy. I should start making them up here and exporting them...

cstreit · cstreit's Garage

Cam, according the people modifying them they do... Figure that the gear has got to be changed, timing changed, unit purchased and reconditioned, buying another CDI or similar unit, etc, etc..

Going rates are about $2k. Fair, heck no! Market bears it I guess...

cstreit · cstreit's Garage

If I could just plug in a 964 distributor into my 3.0L motor, I'd love to know!!! I could fab the wiring for dual CDI's or MSD's m'self.

Tim Walsh · Tim Walsh's Garage

hmm. you're right about the coil packs (ponders some more)

rs911t · 03-25-2003, 07:26 PM

Quote:

I would wonder if the signal from an inductive pickup would be enough to trigger a coil reliably

What about a solenoid or relay? Doesn't a spinning rotor behave like 6 solenoids alternately closing a circuit?

Geez Cam. There you go trying to spoil Chris' beer-induced engineering mania with a out-of-the-box solution! THAT'S no fun!

Tim Walsh · Tim Walsh's Garage

I thought about that but would a relay be quick enough? we're talking millisecond or less here in terms of precision

cstreit · cstreit's Garage

Soooo... is the 964 distributor gear compatible with an SC layshaft?

rs911t · 03-25-2003, 07:30 PM

Quote:

Soooo... is the 964 distributor gear compatible with an SC layshaft?

Nooo, Chris. Fight it!

Randy Webb · 03-25-2003, 07:31 PM

It's more complicated than that -- you take the 964 distributor + the guts from an SC distributor, mix and recurve, then you have a twin-plug ignition. I'd much prefer a good single distributor also...

CamB · CamB's Garage

Yeah I know, I'm a big meanie!

Chris - by the time you add all that stuff up then I guess it does work out that expensive. I understand the SC gear gets stuck on the 964 distributor and then you have to adapt the SC points and advance to work in there too. I have an optical trigger which probably cost me US$300-400 because it was installed and deinstalled so many times (it was a custom job and it kept going into the wrong place). I didn't need advance because I have a MoTeC.

I've added it up before, sort of. I figure the cost of the 964 and SC donor dizzys is the key. Gotta go second hand. 2x MSD and 2x coil, well, I guess they add up too.

Tim Walsh · Tim Walsh's Garage

I think the single dizzy is more elegent as well. If we can get a good signal to the second coil elegently.

How good of a connection do you get from the rotor? (coil to plugwire) good? So-So? terrible?