electrical and ignition 72 Alternator And Distributor Wiring

[Dake]

Preface: I have a Pertronix Ignitor electronic distributor, a Pertronix Flamethrower coil, and an overkill GM 80 amp alternator. The car currently starts, runs for a moment, and putters out / dies / stalls.

 

Question 1. Pic 1. I have the alternator hooked to the belt, battery, and ground. Which wires go to D and D+ on the alternator? What color are they, and is one of them the green wire that ends abruptly in the photo?

Question 2. Pic 1. The two red wires in the picture (coming from the left) are from the ignition, and since the battery is relocated to the trunk I just put them on the positive terminal of the alternator, connecting them directly to the large red wire from the starter (coming from the middle) and essentially bypassing the alternator for now. Is this the correct location for these red ignition wires?

 

Question 3. I currently have the following wires hooked up to the coil: black spark wire, black ground (from distributor to negative on coil), red positive (from distributor to positive on coil), green hot ignition wire (crimped to the red positive and attached to the positive on the coil). Am I missing something? Notably:

Pic 2. There is a black wire which exits a harness behind the distributor but does not connect to anything.

Pic 3. There is also an unidentified black wire which extends from the firewall near the fuse box and ends up just long enough to reach the coil. It has a badly melted endcap.

Pic 4. A black wire extends from the same harness location that the green ignition wire spawns. There are also a brown-black wire and a green-blue wire, but I doubt those are affiliated with the ignition system.

 

Thanks for any help!

Edited January 16, 2014 by Dake

[FunkyLaneO]

I am pretty sure the blue wire should go to the D+ when you replace the generator with an internally regulated alternator.

 

the black wire hanging next to your distributor used to plug into your points, you don't need it any more since you have pertronix, it is just spliced to your tach wire anyway (which is the black wire connected to the negative terminal of the coil). those extra wires in the last picture I believe are probably your windshield washer wires.

[Hans]

If it runs at all, sounds like it is getting some spark. Did you set timing? Alternator shouldn't affect engine running if battery is charged.

Check 2002tii page for wiring diagrams. As stated, one of those black wires is for your tach; sometimes the tach feed goes to dizzy and then on to coil, sometimes it goes to coil and then on to dizzy.

[mnicktow]

I"ll try to post the wiring diagram I have. not very good with computers though.

1972_BMW_2002_and_2002_Tii.pdf

[Chris_B]

1. This is a lot of information to work through here. Presuming that your Pertronix Ignitor electronic distributor is installed correctlyh, do you have a so-called 1 wire GM distributor, or does it have connections on the back in addition to the B+ (from the battery) connection? The one-wire alt. only needs the +12V connecton from the battery and includes a self contained voltage regulator. Even if you don't have the one wire vesion, it is likely that your alt. has an internal voltage regulator, in which case  you would need to hook at least your D+ (blue wire from wiring harness) to the alt to provide charging of the field coils in the alt. But, if you have the 1 wire alt you don't need any of the 02 circuits except a wire from the battery,

 

2. You don't want to have any wires from your ignition connected to any "always on" circuits from the battery, alternator or otherwise. Your ignition circuit should be provided with power from your ignition switch, so you can switch off your ignition when you want to. Don't know where those red wires in your pic come from, but they look way to large to be ignition circuit wires,

 

3. Basically, you need +12V into the coil from the ignition circuit and -12V into the coil (filtered through the distributor (whether points driven or magnetically triggered system like the Pertronix)) in order to fire the coil. Your statement: "black spark wire, black ground (from distributor to negative on coil), red positive (from distributor to positive on coil), green hot ignition wire (crimped to the red positive and attached to the positive on the coil)" is very hard to follow. You will need at minimum a +12V input into the coil and a negative trigger from your distributor. I think maybe your green wire may be a remnant from the ballast resistor/relay circuit from the original 02 wiring.

 

4. Here are a few questions for you. Does your tach work? Does the motor crank over at a normal speed when you try and start it? What kind of induction system are you running? Your problem sounds like more of a lack of fuel than a lack of ignition- ignition systems don't usually crap out after a few seconds of running, whereas lack of fuel can cause that exact problem. BTW, have you checked the charge state of your battery? A lead-acid battery should be close to 12.6V when fully charged.

[Dake]

I guess a rephrase is in order as I don't know where I got D and D+ from. I meant R and F, the sensing and indicator tabs. I have a one-wire GM alternator and I've already got it grounded. So the blue wire goes to F, to the field coils, unless I have a one-wire GM alternator, which I do, in which case it should be set.

 

Chris B, your information was quite helpful for understanding how the whole system interacts. My tach is gone, replaced long ago with a shift light which also doesn't work. I have gotten it to (sort of) idle as I track down a vacuum leak. And once I find a tachometer, the black wire is one of the tach wires.

 

From the distributor to the coil are one red (positive) wire and one black (negative) wire, along with the insulated wire which makes the spark. The green wire was spliced in when I got there, and I just left attached it though I never tried to operate the car without it. Everything seems to be firing well right now, though few electrical systems work.

 

I may think twice before stepping into the middle of someone else's project again. Also a color wiring diagram with more than a few pixels of detail would be priceless. 

[Chris_B]

all factory wiring diagrams include data about wire size and color. Not sure if you said what model year your car is. Couldn't quite tell from the pics. I have a pretty nice pdf of a 12 fuse, mid- 70s car.

[esty]

if you still have the original wires maybe this will help....1972_BMW_2002_and_2002_Tii.pdf