A while back I did a 280ZX dizzy conversion and everything works great. Bypassed the resistor, added a wire from the C terminal on the IGN module to the (-) terminal of the coil. Fantastic. Thing ran great. Still does, however..

While prepping for the addition of an MSD 6AL, I was doing some continuity and voltage tests of the two BW wires that run to the now missing ballast resistor and the (+) coil terminal, I found that both wires have 12+ volts when the IGN is in the OFF position, 12+ volts in the ACC position, <1 volt in the ON position, and <1 volt in the START position. Based on this the coil would be getting less than 1 volt when starting and when running. How can this be? I know this can't be normal but the car runs fine......

I'm so confused.....

Sounds like you are doing a voltage drop test.

A voltmeter will only show the voltage difference between two point, so if you had one lead on the negative battery post and one on the Ignition wire with the ignition turned off you would see 0 volts on the meter.

But if you have the earth lead of the meter on power, eg the positive battery post and the positive lead on the ignition wire, with the ignition turned off, then you will see 12V as this is the difference between the two points. Turn the ignition on and you will have the same voltage at the two points and should see 0 volts.

If you have a bad connection or any other resistance in the circuit you will see a volt or so but you shouldn't have more than 0.25 - 0.5 volts drop.

It only make sense as the ignition is working, hope this helps.

Steven

I'll have to check that out in the morning. Your explanation makes perfect sense. I was really tired so it is very possible. In fact, I'm almost sure that is what I did because nothing else makes any sense. Based on your explanation I was seeing roughly a .34 - .37 volt drop across the circuit. I feel like a friggin' bonehead. Thanks for the reply.

Reminder to self: "Don't play with electricity when you're tired."

Well Steven you were bang-on. What you described is exactly what I was doing. Everything is working now including the tach which required some experimentation with wiring paths. Thanks for the help.

Thats the great thing about forums, your tired late at night cant think straight, ask a question in the forum and some guy on the sunny side of the world who has just had his second cup of coffee for the morning goes "Oh sure i know what that is "

Good stuff, glad it worked out.

Steven

Hey Adam,

I'm getting ready to attempt the same thing, installing a MSD 6AL, with a Blaster 2 coil. Did you have any problems with the tach? Did you use the diagram in the Tech Articles? Can you maybe provide a detail explanation of what you did?

Thanks

Ed

Actually I did use the image from the image from the tech articles as a reference. However, it didn't work for me. I had to splice the RED wire from the tach adapter between the MSD unit and the dizzy, and not between the IGN SW and the dizzy. The tach won't work without the MSD Tach Adapter. The part # is 8910, not 8610. You will need this to get it working.

Note: I already had a 280ZX dizzy installed on my 73' so your experience may differ unless you have one as well.

The MSD 6AL has 6 wires as follows:

Heavy RED - (+) battery terminal

Heavy BLACK - (-) battery terminal

RED - IGN SW (+)

WHITE - Trigger wire from dizzy

ORANGE - (+) Coil

BLACK - (-) Coil

Mounting

I fabbed a mounting bracket for the 6AL and mounted it near the battery, along with the tach adapter.

Wire Routing

I routed the 4 18ga wires(O, B, R, W), along the wire loom that makes its way out to the front of the car on the right side, and across to the other side along the front crossmember, where it makes it's way back into the engine compartment and terminates by the coil. The 12ga power wires (R, went directly to the battery. I bought a used unit so I had to lengthen all the wires. I'm not sure how long the new ones are. If you need to lengthen your wires, follow the instructions in the manual and go up one wire size for the extensions. 12ga > 10ga, 18ga > 16ga.

Conections:

All connections were soldered and shrink wraped. All wires were routed inside a plastic wire loom which was wrapped with tape to seal out dirt and moisture.

Power - 12ga RED (+) and BLACK (-) wires to the appropriate battery terminals.

Coil - ORANGE wire to the (+) side of the coil, and the BLACK wire to the (-) side of the coil.

Electronic Distributor(280ZX version) - The WHITE wire goes to the "C" terminal of the IGN Module or the . The RED wire connects with the BW wire from the IGN SW(original coil (+) wire) and the wire leading to the "B" terminal of the ignition module. I spliced these all together near the coil.

Tach Adapter - Splice the WHITE wire from the tach adapter into the WHITE wire from the MSD box. Splice the RED wire from the tach adapter into the RED wire from the MSD unit.

The last step was to tidy things up a bit by doing a final tape wrap and to zip tie it all up nice and neat. I'll get some pictures tomorrow if I have time and post them here.

Adam

Here's a link to the thread with the install pics.

http://www.classiczcars.com/forums/showthread.php?p=171512

Thanks Adam,

Nice write up. I recieved my MSD stuff yesterday. Getting it all ready and I will hopefully attempt the swap this weekend.

Ed

Here's another link to more pics with a description of each.

MSD Install Pics

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I am a wiring moron. I'll state that right up front just for the record.

What I don't see in your description is wiring for the trigger plug on the back of the MSD unit. If you use the trigger, then you can eliminate the module on the side of the distributor. I had mine wired up with the module to start, then later eliminated the module and used the MSD's internal module.

No hard evidence, but from getting zapped before and after I can say that the MSD does a better job of it.

Adam,

Thanks for the tips and pictures. Nice job. I really like your less cluttered wiring.

jmortensen,

Which way did you connect the two wires on the dizzy to the magnetic

pickup on the MSD? The dizzy wires are red/green and the mag pickup wires are green/violet.

Thanks,

Chris A.

IIRC it doesn't matter.