FSI ignition question

Del in NE Ohio

Del in NE Ohio

Senior Member
Been running FSI 12v distributer in my town sedan now for about 7-8 years with great results. No problems! Love it! So.... this winter I bought one to install in my '31 Truck which has become my weather permitting (NE Ohio)
daily driver. First outing with new distributor, crapped out after approx. 10 minutes. Got a lift back home for rescue distributer. Called FSI and JD sent me another ignitor module. Installed and went for drive today. Same thing again! I think something is going on with my truck (same 12V NuRex Alternator as my town sedan). Talked to JD at FSI and got another ignitor module coming along with a couple of diodes. JD tells me that his late partner, Mel, had come up with a diode install that could protect the module. but he doesn't remember how Mel had customers install those diodes.

Any 'Barners have experience with these?
 
Del in NE Ohio said:
Been running FSI 12v distributer in my town sedan now for about 7-8 years with great results. No problems! Love it! So.... this winter I bought one to install in my '31 Truck which has become my weather permitting (NE Ohio)
daily driver. First outing with new distributor, crapped out after approx. 10 minutes. Got a lift back home for rescue distributer. Called FSI and JD sent me another ignitor module. Installed and went for drive today. Same thing again! I think something is going on with my truck (same 12V NuRex Alternator as my town sedan). Talked to JD at FSI and got another ignitor module coming along with a couple of diodes. JD tells me that his late partner, Mel, had come up with a diode install that could protect the module. but he doesn't remember how Mel had customers install those diodes.

Any 'Barners have experience with these?
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What wire and plugs are you using?
 
My FS ignition has been in my truck since 2015 and 3000 miles no issues. 12v conversion stock dist. 1.5 OHM coil with external resistor. Neg. ground.

"Mel, had come up with a diode install that could protect the module. but he doesn't remember how Mel had customers install those diodes." Sounds like someone that has this modification needs to chime in and share the installation with FSI.
 
FSI module is pretty failure resistant if you install a dedicated ground wire from the distributor points/module plate to the ground side of the battery terminal(no short cuts).
 
Found a guy locally who received a replacement igniter plate with a diode modification done by Mel Mallory last Summer. I'm going to go inspect it this weekend. Both Mel and JD stressed the importance of good ground. On this truck, I've just followed their instructions and utilized lower terminal box screw with paint removed underneath connection. It makes sense to me that if ground is so critical, to go ahead and and run dedicated ground to battery minus terminal. I will post what I find if anyone is interested.
 
I promised an update. I was able to get my hands on a 12V FSI distributor that Mel Mallory had modified for a customer who had experience multiple almost immediate (within a few miles) ignitor module failures. Mel had installed a small diode on the red lead that goes from the module to the positive (+) terminal on the coil. The diode is an IN5404 that is readily available on line or at Radio Shack. It is installed with the silver band (cathode) orientated toward the distributor module. In the photo below, I have peeled back the heat shrink tubing to expose the diode.

As noted in my initial post, I had two similar almost immediate failures. I installed a diode as above, and have been driving for several days now with no problems. My friend who let me check out his modified distributor, has been going for almost a year now.
 

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Del in NE Ohio said:
I promised an update. I was able to get my hands on a 12V FSI distributor that Mel Mallory had modified for a customer who had experience multiple almost immediate (within a few miles) ignitor module failures. Mel had installed a small diode on the red lead that goes from the module to the positive (+) terminal on the coil. The diode is an IN5404 that is readily available online or at Radio Shack. It is installed with the silver band (cathode) orientated toward the distributor module. In the photo below, I have peeled back the heat shrink tubing to expose the diode.

As noted in my initial post, I had two similar almost immediate failures. I installed a diode as above, and have been driving for several days now with no problems. My friend who let me check out his modified distributor has been going for almost a year now.
Click to expand...

Great news!!
 
Thanks for the information regarding the diode installation. I don’t want to beat a dead horse (or Ignition Module), but there are a couple of other thoughts that may help protect the ignition module.

PerTronix recommends not using solid copper plug wires with the module. The solid core wires can cause interference or possibly misfiring. Either situation would not be good for the module. Their recommended plug wire resistance is 500 ohms/foot.

Additionally, PerTronix has an ignition Power Relay Kit (12Volt) , Part Number 2001, that can be purchased from Jegs or Summit, about $35. This relay kit can also be used in a Model A to provide isolation of the 12 volts being supplied to the module from the potential noise on the 12 volt supply, maybe from a fuel pump, fan or generator/alternator. The power could be connected directly from the Battery to the relay, and the relay switched by the ignition switch power.
 
Del in NE Ohio said:
I promised an update. I was able to get my hands on a 12V FSI distributor that Mel Mallory had modified for a customer who had experience multiple almost immediate (within a few miles) ignitor module failures. Mel had installed a small diode on the red lead that goes from the module to the positive (+) terminal on the coil. The diode is an IN5404 that is readily available on line or at Radio Shack. It is installed with the silver band (cathode) orientated toward the distributor module. In the photo below, I have peeled back the heat shrink tubing to expose the diode.

As noted in my initial post, I had two similar almost immediate failures. I installed a diode as above, and have been driving for several days now with no problems. My friend who let me check out his modified distributor, has been going for almost a year now.
Click to expand...

Are we talking positive ground or negative ground?
 
My experience with a electronic ignition was on more modern cars (50s&60s cars) that I had to install a diode to keep the circuit from back feeding and keeping the distributor energized after you turned the key off. Other words, the motor was still running on a back feed. I installed a diode which prevented that problem. I have two As both with FSI ignitions. I wired them exactly according to the wiring instructions and never had a problem. My question is WHY I don't need a diode and Del does.
 
Exactly! My Town Sedan and my Truck are equipped and wired exactly the same by yours truly. The Town Sedan never had a problem, never missed a beat for going on eight years now, but the in the truck, no such luck! Anyway, she's good to go now!
 
im running a 6 volt positive ground fsi will I have the same type of problems or is it just the 12 volt
 
I've been running the Per-Lux Ignitor (now called Petronix) for 30 years in hot rods,classic cars, Model A's and boats with only a couple of failures. Both of the failures were self inflicted and involved grounding. Mickey Remund (Mickey Thompson's engine builder) perfected the Model A and early V-8 systems before selling the operation to FS ignitions.

This product was designed for industrial engine applications running 24/7.
 
Del in NE Ohio said:
I don't think FSI offers a 12V positive ground system
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Thanks for that information as I didn't know that. Shortly after I bought my Model A, I contacted Pertronix asking them if they had a kit for the Model A. They said no but that FSI has a kit that works very well and to contact them. They also said they make the ignitor and sell it to FSI.

I know from another application I have a pertronix in use and at the time I had the choice of 6 or 12 volt positive or negative ground in each both voltage. Choice of 4 ways to go.
 
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