Transistor Module swap *PLS HELP*

[SteveJ]

Here is the page from the FSM with the tach schematic. I would say that the resistor matches the photo.

[Zed Head]

Indeed it does.  The 1975 FSM wasn't available for quite a while, the 76 was a proxy.  Nice that we have a correct copy on CZCC.  I think that mine came from xenonzcar.

The 75 FSM looks like it was typed out using a home-made typewriter.  The worst quality text.  Maye some sort of translation machine.

Edited April 13, 2018 by Zed Head

[EuroDat]

Im not sure where it is exactly on a 75, but on the 77 it's very close to the TIU. Easy to reach and check. You could mistake it for a end plug or end cap to protect the wires.

It has blue wires.

I hope Im not sending you on a wild gose chase. I have never seen it on a early 75.

I snapped a couple of photo's of my 77

[SteveJ]

The 74 FSM has a picture of the resistor that is the same as in the 75 FSM. I did a brief search to see if I could find the old part number. So far, no luck.

On the other hand, I did buy a bunch of 2.2K Ohm resistors about a year or so ago. They are stashed away in my garage somewhere...

[Zed Head]

Aren't we at the point where he just needs to unplug one of those bullet connectors and measure voltage with the key on?  That's my thought.  Seems clear it is the resistor, right?

[SteveJ]

Yes, once he finds which end has the voltage, the other end of the resistor should go to the negative post on the coil.

[Halo8u]

I'll do some more troubleshooting tonight when I get off work. I have the gm hei up near the coil in the engine bay. The wires that ran to the factory tiu in the pass. floorboard are in limbo. What should I do with them? Cut them back and tape them up? Or is there a way to completely delete them?

"Do it in a Datsun"

[Zed Head]

2 minutes ago, Halo8u said:

I'll do some more troubleshooting tonight when I get off work. I have the gm hei up near the coil in the engine bay. The wires that ran to the factory tiu in the pass. floorboard are in limbo. What should I do with them? Cut them back and tape them up? Or is there a way to completely delete them?

"Do it in a Datsun"
 

You probably left the blue wire disconnected in the engine bay.  You should have a wire from the coil negative to the C terminal on the HEI, which you do because it works, and a blue wire to either the C terminal or the coil negative (since they're connected anyway) that runs in to the harness.  It ends up back at that resistor, which is connected to the tach.  It just lets the tach "see" what's happening at the coil.

[Halo8u]

Welp, I'm a dummy. I didn't have the blue wire hooked to the coil. It works great now. Perfect response. Now just to figure out this temp sensor. I bought a new one today. Hope it works.

"Do it in a Datsun"

[Halo8u]

Hey guys. Quick update. Did some research and visual inspections. I have an e88 head on my l28 block. I've heard mixed things about that head. I like the higher comp ratio but idk. I also need a fuel cell because my tank is toast and I'm not trying to spend $400-$600 on an OE tank.

"Do it in a Datsun"

[Halo8u]

Hey guys, so I'm back with more issues haha. So I've been wrenching on the Z for months. It's getting really close to driving condition. I'm just running into another spark issue now. The car cranks, runs, and is quite rev happy when the carb is dialed in. But I seem to have an issue where the car will start, then die maybe 3 seconds of running if the idle is anything under 1500RPM. After I tried all sorts of carb tuning, and idle adjustments, it still wont idle correctly. I pulled a plug wire and did a spark check. Very strong spark, but after a few seconds of running, it stops sparking, and dies. Could this be a wiring issue (I did the gm hei swap as guided through earlier in this thread), or could it be an alternator or voltage regulator issue? Been messing with it for weeks and I'm stumped. Any suggestions? Thanks in advance.

Sent from my [device_name] using http://Classic Zcar Club mobile

[Zed Head]

Are you saying that it will stay running if you keep it above 1500 RPM?  But won't hold an idle below that?  If you set the idle at 1550 it would idle all day?

What is voltage at 1500 RPM and above and below?  That would be a clue about voltage being a problem.  You can watch the ammeter also, if it goes from positive (charging) to negative (draining the battery) when it starts to lose spark, it's a clue.

The magnetic pickup coil in the distributor has an air gap that needs to be set correctly, to generate the voltage for the ignition module.  The voltage passes through the red and green wires to the module, and oscillates from negative to positive.  Also, if you have the red and green wires on the wrong terminals you'll get a rough idle as timing will jump around.  Make sure that green goes to G and red goes to W.  Sometimes the reman distributors use blue wires.   If you're not sure, just swap the wires, and see if it gets better.  It won't hurt anything.  It changes the shape of the trigger pulse from the distributor.