77 280z Restoration

[SteveJ]

Looking at the wiring diagrams:

For the 280Z, I would think the grey wire would connect to the blue wire that goes back to the TIU and tach.

 

[Zed Head]

2 hours ago, SteveJ said:

Looking at the wiring diagrams:

For the 280Z, I would think the grey wire would connect to the blue wire that goes back to the TIU and tach. 

That seems right.  You'd have to guess that they were aware of the tach problems with the MSD boxes and engineered a "tach adapter" right in to the system.  Looks like the same signal that the old ignition module would deliver.  On-off-on-off...12 volts.

The blue wire is branched at the ignition module.  You might be able to just attach the old ignition module blue wire at the Pertronix box, since it's there, (Edited >and cap the blue wire end in the engine bay.)  Not clear if the 2200 ohm resistor is needed.  Probably won't hurt, it's good insurance against shorts.  Stuff to think about.

Edited August 27, 2022 by Zed Head

[SteveJ]

Just now, Zed Head said:

That seems right.  You'd have to guess that they were aware of the tach problems with the MSD boxes and engineered a "tach adapter" right in to the system.  Looks like the same signal that the old ignition module would deliver.  On-off-on-off...12 volts.

The blue wire is branched at the ignition module.  You might be able to just attach the old ignition module blue wire at the Pertronix box, since it's there, and cap the blue wire end in the engine bay.  Not clear if the 2200 ohm resistor is needed.  Probably won't hurt, it's good insurance against shorts.  Stuff to think about.

Agreed. I'm going to write up my suggestions. 

[SteveJ]

I'm thinking this is right, but I'm open to critiques. This is how I would see it going for the wiring. You would need to make sure you lift the wire between the ballast resistor and coil positive. Could this be done without running a single wire out to the coil? sure, but that would require more wire modifications between the dash harness and engine harness.

Edit: Yes, it could be done without running the wire out to the coil, but it would require buying 2 sets of connectors to make jumper harnesses between C-2 and C-3 to intercept the BW wire at those junctions.

Edited August 26, 2022 by SteveJ

[SteveJ]

If I'm correct, these are the same style connectors as C-2 and C-3, though photos of those taken apart would be helpful to confirm.

[SteveJ]

1 hour ago, SteveJ said:

If I'm correct, these are the same style connectors as C-2 and C-3, though photos of those taken apart would be helpful to confirm.

D'oh, Mouser doesn't expect to get any of the 172508-1 until mid December.

[Zed Head]

My comment about capping the blue wire in the engine bay wasn't right.  You need it on the coil.  So you'd just cut the tach branch off of it and use the branch for the trigger wire.  Seems like all of the needed wires are almost ready to go.  It will all make sense once it's in hand.

Looks like SteveJ is trying to get to plug and play, with connectors and all.  I'd probably just set up a terminal strip. 

Anyway,  don't forget to position it so you can see the adjustments.  Good luck.

 

[SteveJ]

51 minutes ago, Zed Head said:

My comment about capping the blue wire in the engine bay wasn't right.  You need it on the coil.  So you'd just cut the tach branch off of it and use the branch for the trigger wire.  Seems like all of the needed wires are almost ready to go.  It will all make sense once it's in hand.

Looks like SteveJ is trying to get to plug and play, with connectors and all.  I'd probably just set up a terminal strip. 

Anyway,  don't forget to position it so you can see the adjustments.  Good luck.

 

It's not exactly plug and play. I just don't like cutting factory wires if I don't have to.

One could back out the BW wires out of C-2 and C-3 and put them into smaller AMP connectors. The dash harness side would go to the key source on the Pertronix. The BW on the engine harness side would go to the BW on the Pertronix. That would save running a wire all of the way from the Pertronix in the passenger footwell to the coil.

[Av8ferg]

Great posts guys.   I’ve already removed my old ignition unit when I swapped to the ZX distributor and e12-80 ignition. I’ve also removed the ballast resistor.   Steve, that’s an interesting approach using the oil ignition wires, might be worth a look.     
 

ZedHead the problem with my mounting in the foot well is that it will be hard to adjust those settings.  I don’t think I’ll ever adjust these once it’s set up.   I’ll se the rev limiter to 6,000 rpm and won’t need the other limiters.   I could mount in the engine compartment and it would probably be fine and I’ll go that route if mounting in the cabin is too hard.  

[Av8ferg]

Was working on the Pertronix Digitsl HP install yesterday without luck.  I wired it up exactly as stated in the manual, and I couldn’tt get the car to start.   Spent 45 mins on phone with tech rep and no luck.   The module has an led that flashes error codes and mine came up as possibly a bad unit.   Bought it on Amazon (because of ease of return),  box appeared to have been opened and instructions were missing.  I think it may have been used before and returned.   So I pulled it out and sent it back today,   You get one shot with me on products.  I won’t come back if I get a bad one.  
So, I’m back to the drawing board.   All this research on ignition units is creating lots of questions. 
It seems the primary cause of many of these ignition unit failures is one of two things.   Heat and/or using the improper coil, burning it up.  The E12-80 module is in a terrible location right under the rad hose on the distributor.  This is a hostile location.   What if you moved it to where the coil is located and just extended the wires from the distributor?  This is what is essentially done on a GM HEI module mod.  
I went ahead and bought an Pertronix HEI to test it out.   Again on Amazon so I can send it back,  it’s a $50 version.   I also bought a heat sink to mount it on.   
I know this discussion has been done before on here and I’ve been looking at those posts.   It seems the GM HEI needs a matching coil to keep it from burning up.   I saw mentions of a .5 ohm coil.    I have a 1.0, .6 and a 1.5 ohm coils here.  (Primary resistance)   
which is more likely to burn up the module to coil a low resistance coil or a higher one?   
I really don’t understand the relationship with coil resistance and what that really means and how that effects the module.  
The HEI seems  to get s bad rap because I think guys have the wrong coil and are just cooking them and/or buying crappy cheap ones,  

I was at my local NAPA , the manager was chatting me up and we are talking ignition units and he was swearing up and down how great the GM HEI is.  He was confident I’d be happy.   
So. I was thinking I could  move the Nissan module mount it on the heat sink I bought and also test the HEI there  Question is can I safely use the 1.5 ohm coil for both.  
Also what do you do about the hole left behind in the distributor where the module wires exit?   I thought o screw a plate where the old one mounted and have the wires pass through a small hole and put a rubber grommet there,  

 

[SteveJ]

Low impedance would translate to more current. More current means more power. More power means more heat.

[Av8ferg]

Thanks Steve, so more likely to burn up a module with a low primary resistance coil.   Safer using a 1.5 coil over a lower one.  
The spark to the plugs would technically be lower too on a 1.5 ohm coil vs a .6 ohm coil.