Pertronix question (Ignition on 'safe-guard'?)

[KevinK7]

I recently installed a Pertonix Ignitor and Flamethrower II coil on my 68 C20 (396). Since I'm still doing work on the truck, I haven't yet attempted to restart it, but I have a question about IGN on and the vehicle not running. I realize this can/will overheat/damage the coil since with the Pertronix recommended hookup, 12V is wired directly to the Coil+ (ie bypassing the factory resistance wire).
Obviously being aware of this, I won't intentionally leave IGN on for any length of time while vehicle is not running, but has anyone implemented any sort of 'safe-guard' to protect ...in the event the key is inadvertently left in IGN when not running?

By "safe-guard" I'm thinking a fuse, ..switch, timer, something that will prevent 'runaway current' that eventually kills the coil and whatever else is in it's path.


Thanks,

Kevin

For reference, this is how I have my Pertronix wired:

[dmjlambert]

I don't think it is normally considered a big concern, because it should be pretty rare to leave the key in the truck and key in on position. If you want to address it anyway, you could add a relay controlled by an oil pressure switch. The oil pressure switch turns on the relay, and the relay connects the coil power, only if the engine is actually running. The yellow wire provides coil power during start before oil pressure is detected and relay is turned on. You would use the same design of wiring that people use to power and safeguard electric fuel pumps, and information about how to wire up an electric fuel pump should be something fairly easy to find online.

The safeguard to protect the coil and electronics is probably not worth the price you would pay introducing the additional potential point of failure and forgoing reliability and simplicity. It is worth the price for electric fuel pump because that is about safety. After a wreck and the engine stops, you don't want the fuel to continue pumping and possibly fueling a fire.

I have not implemented this sort of safeguard, just offering my opinion for what it's worth.

['68OrangeSunshine]

The Ignitor [I] was supposed to burn up if the ignition key was left on. The Ignitor II is supposed to avoid this problem.
Usually the coils and modules were paired up.
Ignitor I, Flamethrower I
Ignitor II, Flamethrower II
Ignitor III, Flamethrower II.
You have the Flamethrower II coil, and an Ignitor One distributor module?
Someone sold you the wrong parts, if so. Get an Ignitor II and don't worry.
'68 Model Year doesn't have the ACC position on the starter switch, so to check your turn signals [for example] you'd have to leave the key on for the test.

[KevinK7]

Originally Posted by '68OrangeSunshine

The Ignitor [I] was supposed to burn up if the ignition key was left on. The Ignitor II is supposed to avoid this problem.
Usually the coils and modules were paired up.
Ignitor I, Flamethrower I
Ignitor II, Flamethrower II
Ignitor III, Flamethrower II.
You have the Flamethrower II coil, and an Ignitor One distributor module?
Someone sold you the wrong parts, if so. Get an Ignitor II and don't worry.
'68 Model Year doesn't have the ACC position on the starter switch, so to check your turn signals [for example] you'd have to leave the key on for the test.

I do have both Ignitor II and FlamethrowerII pair and have heard the Ignitor II does have some level of protection, but the coil is still 'exposed'. Case in point, while troubleshooting my directionals (IGN on) for even 10-15 minutes...........my coil burst. Yup, just like that. My mistake, absolutely (unless defective coil) but there's a sense of uneasiness for that short of time to have an issue. My wiring is as posted and I don't see anything wrong with my setup.
I realize that even with a points set-up (points closed) we run a similar risk of heating up the resistive wire, etc. and I don't want to over-think this, but as you can imagine I want to look into this.
For the record, I've run Pertronix (II) in a couple 1st Gen Camaros and never had an issue so I'm not totally 'new' to them. Yet admittedly I haven't
focused on the IGN on issue(s) as much as I am now.

Thanks,
Kevin

[HO455]

For your piece of mind you could put use the oil pressure switch as suggested. I wouldn't add the relay to the circuit as it only adds more components and connections to fail. Most oil pressure switches will handle the amperage of your ignition system with no problems.
As to your "burst coil" I believe that it must have been defective in some way. I have done exactly as you did dozens of times over the years with no ill effects, as have other mechanics, hundreds of millions of times over the years. Let's not forget all the keys accidentally left on too. Unfortunately it appears you suffered a once in million failure.
The reason that cars started having an ACC position on the ignition switch is when people started using their radios without the engine running they would damage the points. Back in the days of point ignition if the points were opened just right when you had the engine off but the power supplied to the coil the points would continously arc and destroy the contacts. Then the engine would run poorly if at all. So there actually was a reason that car a wouldn't start after parking at lovers lane listening to the radio for an hour or so.
I do have a question on your wiring diagram. Why are you running the ballast wire to the starter solenoid instead of to the coil where the factory did? If you replace the ballast wire with a regular wire then you would not need to run the blue wire from the fuse panel.

['68OrangeSunshine]

Sounds like a defective coil to me too. They should swap it out under warranty.
The Ignitor II is not supposed to burn up when the key is left on. If you connect to the Coil with a blade style terminal, you can make a temporary disconnect, for tune up purposes.
On the other issue HO455 is right. You should have a cut out switch on the elec fuel pump.
I learned that the hard way. I didn't think I needed yet another impediment to starting, so I skipped the oil pressure switch on a Holley Red fuel pump inline with the fuel tanks feed to the 454 in my '67 K/10 Suburban. One morning, after topping off with the wrong fuel, I had a stall and a backfire and my oil-saturated K&N air filter caught fire. I got my dog out of the truck and safely in a ditch but had left the key on and the fuel pump was flowing 91 octane into the carb fire. Lucky for me, some guys came out from the business across the street with fire extinguishers, but that killed my Suburban.

[Corts60]

Here is the oil pressure switch you'd need to run if you want to avoid a relay. Read in the comments that this switch can handle 10 amps. Easy and cheap fix to your problem.
https://www.summitracing.com/parts/c...caAvQCEALw_wcB

If you wire it per the instructions, you will have no power going to the coil with key on, engine off position. Coil will only get power during crank and when oil pressure is there.

[KevinK7]

A huge Thanks for all the replies, seriously. Also,, I am looking into the oil pressure switch idea for sure.
HO455,
The ballast wire (assuming you mean the resistive wire) was running to the starter solenoid 'R' lug from the factory. The only thing I added was the wire to the coil + (from fuse box IGN).

I had planned to call Pertronix today (re: possible defective coil), but got too busy at work and never had a chance. I'll update what I hear from them.

['68OrangeSunshine]

You can take the Yellow 20 wire [Or/Pur/Wht] resistance wire going to the coil and tape it off, and tie it back. You don't need it any more. Keeping the line allows you to fall back on points when the Pertronix fails, before you swap for a GM HEI.

[HO455]

Originally Posted by KevinK7

A huge Thanks for all the replies, seriously. Also,, I am looking into the oil pressure switch idea for sure.
HO455,
The ballast wire (assuming you mean the resistive wire) was running to the starter solenoid 'R' lug from the factory. The only thing I added was the wire to the coil + (from fuse box IGN).

.

Interesting I was working on a pretty unmolested 70 a couple weeks ago that had the ballast to the coil and the yellow on the coil.

[HO455]

Originally Posted by '68OrangeSunshine

You can take the Yellow 20 wire [Or/Pur/Wht] resistance wire going to the coil and tape it off, and tie it back. You don't need it any more. Keeping the line allows you to fall back on points when the Pertronix fails, before you swap for a GM HEI.

I've seen too many HEI failures over the years to trust one over a basic Pertronix unit or points. Around town daily driver okay, but no way I would go offroad into the back country or any other place with no tow truck nearby with an HEI.
Just my opinion.

[Corts60]

Originally Posted by HO455

I've seen too many HEI failures over the years to trust one over a basic Pertronix unit or points. Around town daily driver okay, but no way I would go offroad into the back country or any other place with no tow truck nearby with an HEI.
Just my opinion.

Funny all the different experiences we all have. I have never had an HEI unit fail on me, but have had several pertronix units fail including an entire pertronix distributor that wouldn't keep timing due to loose tolerances.

['68OrangeSunshine]

Originally Posted by HO455

I've seen too many HEI failures over the years to trust one over a basic Pertronix unit or points. Around town daily driver okay, but no way I would go offroad into the back country or any other place with no tow truck nearby with an HEI.
Just my opinion.

Surprised by your Pertronix loyalty. They haven't done anything to earn that kind of loyalty from me.
I ran the Ignitor II/Flamethrower II set up for about 7 years. Then it would cut out on my 292 just as it got above 3000 RPM on the freeway, and cold-crank, the whole operating assembly spinning at 60 -65 MPH with no spark. Cutting the Ign switch off then on, slowing to 50, I could pop start it and get running again, but that put a lot of strain on the moving parts. It did this everytime my RPMs went into that range.
I sent the unit back to Pertronix, at the suggestion from their tech rep. And never heard from them again.

I went back to points for a year. I had a lot of old school NIB parts, a Dwell meter, and experience with that system.

Finally I got an HEI L6 distributor with a low profile cap and remote coil, and have run that for about 4 years. Really great performance upgrade.
Parts logistics is much better with the more common GM HEI system. If a module burns out, I can go into any parts store and have my old one tested and buy a new one if it's shot. Swapping out the GM Module can be done in situ in 10 - 15 minutes. No further adjustments necessary. I keep spare [known good] HEI modules in the glove boxes of both my trucks. It's the same part for L6 or V8.
If a Pertronix module burns out? Good luck. It was 5 years ago and I'm still waiting.