what is the work around for replacing the pickup coil in my distributor?

[fredmeister]

I went to the parts pages looking for the signal generator in my 79 930 dizzy:

Pick Up Coil (Pulse Generator) for Ignition Distributor, 911/911 Turbo (1978-89)
Brand: Bosch ----

This part is no longer available!

What is the work around that you guys are using to replace this part if its bad?

I checked my resistance at the ends of the plug into the green signal wire and its within spec, but I dont know if its breaking down when it gets hot since the turbo really cooks the hell out of the distributor cap and rotor and everything inside there.

I dont want to replace the dizzy entirely as an only option if this part goes bad.

Fred

[mark houghton]

Screw it, just retrofit an old points type ignition. That and a cheap ass NAPA coil, set the point gap to .016 and rock! (sorry, only old farts know of points ignition). Glad I could help......

[JFairman]

I wonder if the one for an SC would work if you find one. They use the same cap and rotor so the distributor housing is the same diameter.
You might get some information from Henry or Steve and others on the engine forum. There's someone mentioned on that forum named Aaron that rebuilds them.

When it gets to the day all these distributors are used up and the cars are still around then crankfire ignition like electromotive or EFI with coil on plug or wasted spark ignition will probably be next.

[jsveb]

My guess is, the guy Jim is referring to is Aaron from Burn bros in Ca. Another guy who has got an excellent reputation, as far as I know, is Barry Herschon (spelling)

[Speedy Squirrel]

There are a number of aftermarket (non-Bosch) ones. For instance:

******** Parts Catalog

Are you sure it is bad? Did you measure the resistance between the two pins?
It is the same part for a lot of vehicles.

1981-1983 Alfa Romeo GTV-6
1979-1981 BMW 528i
1978-1981 BMW 633CSi & 733i
1981-1982 De Lorean DMC12
1978-1981 Mercedes-Benz 280CE
1977-1981 Mercedes-Benz 280E
1977-1980 Mercedes-Benz 280SE
1984-1985 Mercedes-Benz 380SE
1981-1983 Mercedes-Benz 380SEL
1981-1985 Mercedes-Benz 380SL
1981 Mercedes-Benz 380SLC
1976-1980 Mercedes-Benz 450SE 450SEL 450SL 450SLC
1984-1985 Mercedes-Benz 500SEC 500SEL
1977-1980 Peugeot 604
1978-1984 Porsche 928
1980-1982 Volvo GLE
1975 Volvo 160 series
1976-1979 Volvo 260 series
1983-1986 Volvo 760

[T77911S]

i suspected the same thing on my car. thats why i put an Oscope on it and found the signal upside down. i almost sent mine off to have the advance checked and the coil.

what are your AFR's at 2500 and 3k in 3rd gear?

what are your current symptoms?

[fredmeister]

Originally Posted by Speedy Squirrel

There are a number of aftermarket (non-Bosch) ones. For instance:

******** Parts Catalog

Are you sure it is bad? Did you measure the resistance between the two pins?
It is the same part for a lot of vehicles.

1981-1983 Alfa Romeo GTV-6
1979-1981 BMW 528i
1978-1981 BMW 633CSi & 733i
1981-1982 De Lorean DMC12
1978-1981 Mercedes-Benz 280CE
1977-1981 Mercedes-Benz 280E
1977-1980 Mercedes-Benz 280SE
1984-1985 Mercedes-Benz 380SE
1981-1983 Mercedes-Benz 380SEL
1981-1985 Mercedes-Benz 380SL
1981 Mercedes-Benz 380SLC
1976-1980 Mercedes-Benz 450SE 450SEL 450SL 450SLC
1984-1985 Mercedes-Benz 500SEC 500SEL
1977-1980 Peugeot 604
1978-1984 Porsche 928
1980-1982 Volvo GLE
1975 Volvo 160 series
1976-1979 Volvo 260 series
1983-1986 Volvo 760

Measured the resisitance between the 2 pins, well actually at the ends of the wire coming off the green coax cable and was 585ohms.

I think this is within spec so it seems good, I was just wondering if it could be breaking down when it gets hot from all the turbo heat when its running under load.

I would just like to have my eggs in a basket when these parts need replacement. Maybe stock up on one now for the future when it truly is NLA.

Thanks,
Fred

[Speedy Squirrel]

That sounds nominal. The coil is probably OK. I guess you could always try and measure it hot. It's rare but not unheard of to fail hot.

Stocking up is a good plan. The Double acting vacuum pot is also getting hard to find.

[jpnovak]

Since you have an MSD ignition I would replace the whole insert with a Crank Optical. I did this on an SC distributor I made into a twin plug unit. Worked great. The plus side is that you have a 12V output square wave that is much less susceptible to noise unlike the mV scale coming from the coil and spider arm.

Are you sure you don't have a break in the green wire somewhere that separates when hot? Are you getting cut out?

A friend had a distributor with too much vertical play. The distrubutor would float and there would not be enough overlap between the spider and pickup coil. This caused a low voltage signal and lots of cut out. It was not easy to find that one.

[fredmeister]

Originally Posted by jpnovak

Since you have an MSD ignition I would replace the whole insert with a Crank Optical. I did this on an SC distributor I made into a twin plug unit. Worked great. The plus side is that you have a 12V output square wave that is much less susceptible to noise unlike the mV scale coming from the coil and spider arm.

Are you sure you don't have a break in the green wire somewhere that separates when hot? Are you getting cut out?

A friend had a distributor with too much vertical play. The distrubutor would float and there would not be enough overlap between the spider and pickup coil. This caused a low voltage signal and lots of cut out. It was not easy to find that one.

I just tightened up the clearance on my dizzy before I installed the MSD unit. I had a lot of vertical play in the dizzy shaft because I think the shim stack was missing a part or had just needed to be rebuilt, but I installed a shim to bring the end play back into spec. I dont think floating is an issue and it wasn't giving me any ignition problems before I made the adjustment either.

Green wire is new, I replaced that with the new 928 part and wired it directly to the MSD harness. Even went so far as to isolate the signal wiring away from other voltage sources and spark plug wires as best as possible....thinking some EMF from plug wires or other sensor wires in the engine bay might be causing problems.

Question: This Crank optical unit fits inside the OEM distributor housing in place of the coil unit and spider gear? Or is this something driven off the crank pulley?

Fred