280ZX Distributor Upgrade

[RawlinSTR]

Hi all,

Going through the motions of trying to get my '73 240Z started.

I bought it without an engine but the car had previously been running (before I got it) with a 280ZX distributor so all of the modifications required have been done I think.

The car also came with a MSD coil (MSD blaster).

I'm getting no spark at the moment so I have a few questions.

1. When should I be seeing 12V at the coil? When the key is turned to 'start' only, or when the key as turned to 'on' as well?

2. At the moment the only wires I have going to the distributor are the ones from the coil to the 'B' and 'C' posts on the ignition module. In some posts/ guides on upgrading from stock to 280ZX, the dizzy mount is also grounded with a single wire. Is this necessary?

3. So I can check some things, is this definitely a correct schematic? Any key differences between a 71 - 72 and a 73 240 that I should know about?

I still need to do some proper diagnosis with a multimeter but I thought I'd ask in advance of me going and doing some further investigation.

Thanks and as always, advice is appreciated!

Simon

 

[jonbills]

Hi all,

Going through the motions of trying to get my '73 240Z started.

I bought it without an engine but the car had previously been running (before I got it) with a 280ZX distributor so all of the modifications required have been done I think.

The car also came with a MSD coil (MSD blaster).

I'm getting no spark at the moment so I have a few questions.

1. When should I be seeing 12V at the coil? When the key is turned to 'start' only, or when the key as turned to 'on' as well?

Both start and on. If you're using the ballast resistor still, 12v at start and 8 at on. But you don't need the ballast resistor so I'd move the feed from the rear terminal to the front terminal, then you have 12v at start and on.

2. At the moment the only wires I have going to the distributor are the ones from the coil to the 'B' and 'C' posts on the ignition module. In some posts/ guides on upgrading from stock to 280ZX, the dizzy mount is also grounded with a single wire. Is this necessary?

I've tried with and without the ground wire and found no difference. If you tried really hard to make sure the dizzy body was not in contact with the engine metal then maybe the ground would be needed.

3. So I can check some things, is this definitely a correct schematic? Any key differences between a 71 - 72 and a 73 240 that I should know about?

It looks right to me, although can't swear to the wire colours.

I still need to do some proper diagnosis with a multimeter but I thought I'd ask in advance of me going and doing some further investigation.

Thanks and as always, advice is appreciated!

Simon

 

[johnymd]

Diagram looks good. 12v to coil with key both on and start.

 

[RawlinSTR]

Thanks Jon, I think I need to start just ringing you every time I have a question!

I can’t see the ballast resistor anywhere so I think it’s been removed.

Thanks Johnny.

I’ll do some more diagnosis today and see what I can find.

 

[RawlinSTR]

Managed to solve the issue, I tracked it down to a faulty E12-80 ignition box, luckily I had a spare to try!

Thanks for the help both.

 

[Rob Gaskin]

This diagram is quite good at understanding the ign feed to the coil and how long it is! Consider that the ballast resister is actually located by the coil. Therefore the ign feed goes all the way from the ign switch to the coil area (across the front of the car), back to the dash loom and then back to the actual coil through the tacho. Then consider how many times at 6k rpm that circuit has to decay and build again in the coil!

 

[Faster Behr]

This diagram is quite good at understanding the ign feed to the coil and how long it is! Consider that the ballast resister is actually located by the coil. Therefore the ign feed goes all the way from the ign switch to the coil area (across the front of the car), back to the dash loom and then back to the actual coil through the tacho. Then consider how many times at 6k rpm that circuit has to decay and build again in the coil!

I don't suppose anyone has a copy of the diagram referred to above? I have similar issues and am trying to understand the ignition and tacho wiring. I have the 280ZX distributor, no ballast resistor and no working tacho also.

 

[Farmer42]

Try this website which I used to sort my 280zx dizzy a few years ago.

http://www.atlanticz.ca/zclub/techtips/distributor/

 

[johnymd]

If you don’t have a working tachometer then the 2 wires at the coil that make up the tachometer loop are not connected correctly.

I don’t have a diagram in front of me but the principle is this:
12v supply from ignition goes to coil area and connects to wire back to tachometer. Wire back from tachometer goes to coil +.

The tachometer just senses to pulses to the coil positive, simple.

 

[johnymd]

Just notice Rob explains it well and I’ve pretty much copied what he said.