Update. Well I tried the MSD solution for one reason or another I could never get that upgrade to work - although I know now what was keeping it from working.

Anyway, I bought a new Ignition Module and plugged it in - Problem solved. I also changed the coil with a new Accel coil and I believe this resolve the Tach needle hop that I had from time to time.

I opened the original Ignition Module and it was full of Media Blast material from when the car was stripped during paint. The Media Blast particles were probably heating up and causing the module to shut down. Now Knowing this information, when someone is experiencing intermittent ignition problems (especially after the engine had been running for a while), it might be resolved by opening the module up and spraying the circuitry down with circuit cleaner to remove dirt and grime. These old school transistorized ignitions are pretty tough and durable.

IMO, the module (failing) was causing the tach to jump around.

I replaced mine based on suggestions from forum members. The car would suddenly start bucking, misfiring, eventually stallin, similar to runnung out of fuel. Restarting could happen immediately or it could take awhile.

It wasn't until this had happened a couple of times within a few days that I noticed the tach needle going nuts during an "episode". I'd not noticed it before 'cuz the sh@t would always happen on the freeway or in the middle of traffic. I was more concerned looking for a landing zone than to watch the dash.

Edited November 6, 201212 yr by Willoughby Z

I wanted to update everyone to my solution to the intermittent ignition problem that I was experiencing last fall. To catch you up here is the original post:

So, I took my Z for a spin today, zipped around for a bit and topped off the tank will 5 gals of fresh fuel. When I was done at the gas station I hit the frontage road (feeder road here in Texas) and just as I was going to enter the freeway - NOTHING, no bang, no pop AND no ignition. The engine just quit.:mad: The engine would crank strongly, but no ignition.

I checked the fuses, fusible links, cable to EFI -all good. The fuel pump is working well, because hear it and after much cranking I could smell fuel at the tail pipe. I bought a new Ignition Module and plugged it in. (I opened the original Ignition Module and it was full of Media Blast material from when the car was stripped during paint. The Media Blast particles were probably heating up and causing the module to shut down). I also changed the coil with a new Accel coil and I believe this resolved the Tach needle hop that I had from time to time. [\QUOTE]

So after all of this I believed the problem was fixed. Well I got it to the end of my street and the beotch quit again! While trying to restart, I noticed that the engine would sort of fire while I wiggled the key - this led me to start looking at the entire Key Lock and Ignition Switch assy. This made sense because this was the only part of the ignition circuit that I had not changed. So I ordered a new one and installed it. Now the Z starts right up and runs well - more importantly stays running! In retrospect I should have looked at the Ignition Switch assy earlier since it was kind of sloppy (I could pull the key out while it was running). It sure is nice to have the Z running and a nice tight Key Lock.

So there you go mates, I hope this can help someone else out who's chasing grimlin's in the ignition...

Thanks for providing additional info, Andrew.

My key comes out easily in the "Run" position, as well. I might be only miles from the same failure.

Carry a can of starting fluid with ya. If it'll start on faux fuel, then it's an ignition problem. You've got to determine if it's on the fuel or ignition side before you can go to step 2.

The fact that you JUST FILLED UP suggests to me you got a load of water in your gas, or debris which clogged the fuel filter.

If faux fuel doesn't allow it to start, pull a plug wire and see if you get an arc.

If not, check from the coil to the distributor.

No arc out of the coil, check the connector on the distributor and see if it's loose.

My '75 from long ago had a removable ignition key for years, without any running problems. The ignition switch is actually a separate part from the lock cylinder, so you can wear out the cylinder without affecting the switch.

But ye beware of cheap ignition parts! I installed brand new taiwan-made 20$ switch to my Z. It lasted couple of months and then started to behave just like that. Now i have ye olde switch on place and no problems..

This was a complete Key Lock and Ignition Switch setup - $150 from Advanced Auto Parts. I figured if I were in it, I might was well change all of it. The only part I am hating now is that I have two keys instead of one. Bummer.

If the new ignition key fits into the other locks but doesn't turn, you can get the ignition rekeyed. If it doesn't fit then it's a reversed key blank and you would have to find reverse lock cylinders and have them keyed to the new key.

I hate the 2 key way. One day I will change all locks out. Nice clean 78! Wish mine looked as good.

I hate the 2 key way. One day I will change all locks out. Nice clean 78! Wish mine looked as good.

Thank you, Sir! I agree, I am hating it too. I see a complete lock change-out in my future!

Wish I had 2 keys, I have one each for the ignition, doors and rear hatch. The local locksmith's wanted $100-125 per lock to re-key all the locks to one key! My ignition key also comes out in the Run position, but I haven't had any issues, yet.

Edited March 20, 201312 yr by mjr45