TheSamba.com :: View topic - Troubleshoot pertronix flamethrower and distributor

Thu Jan 02, 2020 6:22 am

This is my first forum question, I did search through old posts but was unable to find a similar issue.

Finally got back to working on my 1972 ghia. In it's original configuration it ran about as well as it did 10 years ago. I bought pertronix flamethrower ignition coil and distributor, plugs and wires. Pulled the plugs and they were pretty black (bad spark, too rich, probably both). Replaced plugs and wires, car fired right up.

Replaced coil and bypassed inline ballast resistor, car would not start (turns over, has fuel, no fire), added resistor back in, no change. 3ohms across coil, and with a better ground wire, I get 10.8V across +/- terminals (voltage across battery is 11.5, so there is some loss in the system but tech specs for flamethrower says 10V is in the ok range). Not sure how the old coil even worked with out the solid ground. Put old coil on, car fired up again.

With old ignition coil in, I replaced distributor (SVDA from jbugs) car would not start. It's wired properly, all cables tight, firing order right, good ground, etc.

With both new coil and distributor, car does not run (not surprised but thought i would try the last combo).

I am fairly confident that going back to the original configuration, the car will start. I know that coils can be cooked if left on too long without discharge, but I'd expect the resistance to go up if that were the case. I'd be surprised if both pertronix parts were duds. I opened the distributor up and verified that the hall switch is working.

Does anyone have experience with this? Do I need to track down my 1V loss? I could easily jump a wire with battery voltage as a test. Can the voltage regulator be the source? Why would all new combos not work? Other help or thoughts?

Thu Jan 02, 2020 9:29 am

You have to set the initial timing on the new distributor to get it to start.

What's the voltage at the battery?

Thu Jan 02, 2020 9:37 am

I get 11.5 across my battery terminals. And closer to 10.5 across my coil which is the same as my distributor leads.

At cyl 1 @ TDC i have the distributor pointing to the 1st cylinder same as i would do with my vacuum advance stock distributor. Is there another step to setting the initial timing on the solid state controlled pertronix?

Thu Jan 02, 2020 9:45 am

I usually go for 12V on the battery and no lower.

What coil (specifically) do you have?

What resistance measurement across the terminals do you get? It should be around 3?

What distributor do you have? Electronic ignition or points? How do you have the ignition hooked up? Would you post some pictures?

Thu Jan 02, 2020 9:58 am

Modified wiring diagram shows my connections. Spec sheet for distributor says 10V and greater is sufficient.

Dist: pertronix svda 186504
Coil: pertronix flame thrower 40611

3ohms across coil.

Original dist was points. new is electronic, verified hall switch is working.

Thu Jan 02, 2020 10:59 am

I experienced exactly the same problem when I converted over to the Pertronix III dizzy and coil.

The issue was the new sparkplug WIRES.

The dizzy is ONLY compatible with certain types of wires. I had some notes from when I talked with Pertronix technical service, but can't seem to find them now. I don't trust my memory except to advise you to call them.

Once I installed the correct type wires as they advised, she ran/runs like a champ.

IF you are CERTAIN (by verifying) that you have compatible wires, I have no further advice.

GOOD LUCK!!

Tom

Thu Jan 02, 2020 11:09 am

I bought pertronix flamethrower 7mm wires pt704101. They work with the old dist and coil. But maybe these are the issue for the new one, do you have any record of the compatible set? I bought all of these items from jbugs with the 72 ghia compatibility selected, but it doesn't mean i have the right combination.

Thu Jan 02, 2020 2:03 pm

Sorry, but I don't have the notes that I made during my phonecon with Pertronix Technical.

Look up the phone number for their tech line and give them a ring. They were most helpful when I talked with them.

Again - GOOD LUCK!

Let us know how it works out.

Tom

Sun Jan 05, 2020 6:54 am

I spoke with pertronix support, my wires and plugs are compatible.

I went back to the original setup with the old distributor and coil. In going back to the original setup I removed a grounding wire that I had added to match the wiring diagram. The car would run again in the original configuration. While it was running I touched the grounding wire to the negative terminal of the coil and the car immediately began to stall and recovered when I removed the ground. Without the grounding wire that I had added, with the car in run, I can't measure any voltage across the coil. When the car is running I measure 6v across the coil despite the coil being a 12v coil. On the + terminal of the coil there are several wires since it's being used as a branch point. One wire that I don't know where it goes is green and white, another is black and looks like it goes to an inline fuse.

Does any of this electrical oddity help diagnose my issue?

Sun Jan 05, 2020 10:58 am

Can’t tell you about your Grn/Wht wire. Seems like a replacement or an add on.
The black with the fuse is for your reverse lights.

Wed Jan 08, 2020 2:52 pm

Claymore12 wrote: I spoke with pertronix support, my wires and plugs are compatible.

I went back to the original setup with the old distributor and coil. In going back to the original setup I removed a grounding wire that I had added to match the wiring diagram. The car would run again in the original configuration. While it was running I touched the grounding wire to the negative terminal of the coil and the car immediately began to stall and recovered when I removed the ground. Without the grounding wire that I had added, with the car in run, I can't measure any voltage across the coil. When the car is running I measure 6v across the coil despite the coil being a 12v coil. On the + terminal of the coil there are several wires since it's being used as a branch point. One wire that I don't know where it goes is green and white, another is black and looks like it goes to an inline fuse.

Does any of this electrical oddity help diagnose my issue?

If you ground the negative post of the coil the coil won't work properly and the car will not run.

To check the voltage at the coil take your volt meter with the red lead touching the positive post on the coil and the black lead grounded to the engine block or alternator or generator body. You should be able to get a voltage reading then if the engine is grounded through the tranny properly.

Sun Jan 26, 2020 1:50 pm

Figured I would complete this post with some of the things that were going wrong.

Wiring diagram shows the negative terminal of the ignition coil is connected to ground, this was wrong but I have seen it in a few wiring diagrams.

There was also an issue with the distributor it was like 1/8 inch too high and not seated properly.

I was also having carb issues complicate the diagnosis (stalling engine when warm).

I have now gotten the car running with all old parts, new coil with old distributor, and new distributor and coil. It seems to run best with the old vacuum advance distributor than the new solid state device.

Sun Jan 26, 2020 1:58 pm

Sun Jan 26, 2020 2:57 pm

Wow, mine measured the same when I put them side by side.

I feel like the flame thrower doesn't advance as well as my old vacuum on quick acceleration/ throttling. Verified with my timing light, same problem as when I had a centripetal advance. It is slow to advance it can cause a backfire.