Which 6-cyl car has external ign.box? (CDI went kaboom..argh)

[Zendalar]

Yes..I have had troubles with my Bosch 3 pin ignition box. Now I got tired of being left on the side of the road along with huge bang from the exhaust.

I Did not drive the car in 2 weeks (was on holiday) and so it (THE car) propably got pissed about the situation and destroyed the CDI box just to annoy me. Well, it works, sometimes..but thats not good for me and I am tired of opening the box.

Here I am asking if you know which 6 cylinder car has an external voltage regulator which I could use on my 911T (-72).

High voltage coils can be bought cheap after the alteration, so I reckon the ignition spark will be as strong as it was with Bosch when it was working.

Wonder what to do with the tacho...CDI box gives constantly 4-5V out and when triggered, pulse of 440-460V. Do I need to do anything with the tacho?

Suggest me what to do

Thanks in advance

[Roland Kunz]

Hello

Make sure the CD box has good ground and no erratic powerr suppley.

Also make sure your distributor, wires, spark plugs & connectors and contact are ok. ( If you have a Marelli then look twice or swap for a Bosch unit )

Also the 2,4 has a additional air circuit on the Carbs wich lead to bad runing and missfireing if not working correct.

Now retrofiting to a normal ignition is possible. You need a condensor on the contact and run the unit from a conventional coil.

I would sugest to look for old Volvo 2 series V6 or Turbo K-Jet cars as they have a high performance 9 Volt Bosch spark system wich will have enough ZAP for a 911 too. It still isn´t the same ZAP a CDI makes

Tach should work.

On the Voltage regulator you have to visit a local parts store and look into there crossreference list. Something from Hüco, Wehrle, Hella or Bosch is working.
Get a full electronic unit like used in the mid 70´s Volvos.

Make sure your Voltage regulator on the car is the correct one for the alternator and not replaced by a wrong unit before.


Grüsse

[Matt Smith]

MSD

[pwd72s]

Zendalar? Check this thread...If I wasn't so hung up on "original", I'd go MSD in a heartbeat..
http://forums.rennlist.com/index.html

[CamB]

I think Paul means this thread:

http://forums.rennlist.com/cgi-bin/rennforums/ultimatebb.cgi?ubb=get_topic&f=1&t=003328

I agree - MSD is cool and much cheaper than a secondhand Bosch CD box. Plus the coils are 1/4 the price if you ever need to replace.

[Zendalar]

I was thinking of Allison/Crane XR700 because its cheaper But Which works better?

[Matt Smith]

MSD

[Early_S_Man]

Zen,

How about a used Bosch CDI-unit and coil from a Mercedes 280/450 series V-8 from the early '70s thru mid-80s? The connector wasn't the same, but it was a four-wire system (including the ground wire) using points? Should be relatively plentiful at salvage yards ... and inexpensive???

[Matt Smith]

Hey Warren! I've heard of that idea somewhere before...
Didn't John walker find something different about them?
If not, they seem to be a good substitute (to MSD).

[Early_S_Man]

Matt,

If I remember correctly ... he said the Bosch part number was different and that the wiring connections were a different style. It has been about 12-15 years, but I seem to recall a terminal block on the box ... which from appearances (except for connector) is identical to the 3/6 pin 911 units.

[porsche74]

Originally posted by pwd72s
Zendalar? Check this thread...If I wasn't so hung up on "original", I'd go MSD in a heartbeat..
http://forums.rennlist.com/index.html

Paul:

I can surely appreciate what you are saying,.....especially with your car, but the performance gains are well worth it.

Years ago, working on a 917/10 which is the most plug-fouling SOB there ever was, we installed a pair of MSD 6AL's in a hidden location that left the original CD boxes in place with all wiring. You could not tell anything was changed or different. Further, we used a pair of MSD coils and painted them to look like the Bosch ones.

It started, idled, and ran SOOO much better,... Changing 24 plugs is no fun at all.

[Roland Kunz]

Hello

Zen is in Finland and i guess Volvos are the easiest to find.

Will cost him not very much and he can find out if it will stop his trouble.

If yes he still can opt for other Ignition solutions.

If not he can focus on the other problems and fix them with his budget.

The Mercedes CD units are rare and sought after by Mercedes guys in europe.

Mercedes was the first to use hall triggered CD units.

However Bosch is a very modular system and used in Volvos, Saabs, Peugots 6 cyl from that age too.

I didn´t understand the external voltage regulator quest so i went sure on that subject.

Now the advantages from the CDI units is whenever the mixture is very lean or to rich ( wet ) when normal ignitions would foul.

Grüsse

[Zendalar]

What I found out about my current CDI system that it works...from time to time. You have to hit it with your fist it to get working again. You can hear it from the whine..and from the current it takes. When it does not work the car stalls immediately, fuel pump starts pumping slowly and lights dim. I hit the box and the whining of CDI box is more...even and healthy.

That box had that same problem last year, the wire that goes to the big capasitor inside had a loose solder joint. Now I believe the problem has renewed itself...lets hope the solder is not cracked directly from the capasitor end (from the insides of the capasitor)

If I can't fix it, i will go directly to MSD or Allison/Crane...or perhaps to conventional capasitor+coil system

[911pcars]

"..I was thinking of Allison/Crane XR700 because its cheaper But Which works better?"

One shouldn't compare the Crane XR700 with the MSD 6A and 6AL boxes as the XR700 is a breakerless conversion kit (like the Pertronix). The MSD units are high-voltage spark boxes which may be triggered by breaker points or otherwise. The Crane units to compare are the Hi6 units which, save for a few details, are fairly equivalent.



Sherwood Lee
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www.seinesystems.com