Electronic Ignition and your Borg Warner Overdrive

The question often comes up when a customer upgrades the original mechanical points ignition system to a more modern electronic ignition...how to I make my overdrive kick down switch work with my new HEI electronic ignition? Well... there is no simple answer as it turns out. It depends on the kind of electronic ignition you have.

The most common upgrade appears to be a GM style HEI ignition from the aftermarket or from a salvage yard. They are cheap and fairly simple to adapt to most any application. The problem is using it with a Borg Warner overdrive... how do you ground out the ignition of an HEI type electronic ignition using the kick down switch so the overdrive can shift without being under load.

Originally the ground wire of the kick down switch went to the negative side of the ignition coil. Because that side of the coil was not fused and there were no solid states pieces and parts involved, all worked well.

But because and HEI uses a solid state module to provide the spark, that solid state module that is very voltage sensitive. So if you suddenly ground the ignition out on the output side of the ignition module just as you did with the old mechanical point ignition, you will create a huge voltage spike.

Because there is no condenser to absorb the voltage spikes (because solid state electronic ignition systems does not need one) there is nothing to absorb the voltage spike created by grounding out the ignition...except...you guessed it, the solid state ignition module, which quickly zaps your ignition module and your vehicle is dead in the water because you have no ignition spark.

Some HEI ignitions have an inline fuse that will protect the module from excessive voltage but the end result is that you will blow that fuse every time you hit the kick down switch. I know what you are thinking....I will just take out that fuse or put in a bigger one. Then you will for sure burn out the ignition module which is why the fuse was put there in the first place.

Some customers have tried to use the tach drive terminal on the HEI ignitions to run the kick down switch. While that terminal is a ground terminal, that typically does not work either... A tach creates no voltage spike unlike the kick down switch which does. It is that voltage spike thing again.

So basically any electronic ignition that has the coil built into the distributor will likely be damaged when you engage the kick down switch from the overdrive.

One solution might be to setup a way to interrupt the battery current going to the electronic ignition on the incoming (battery) side to the the electronic ignition itself. That is something you will have to engineer based on your application.

The other kind of electronic ignition you see is the Pertronix style that fits into the original distributor and replaces the mechanical points with an electronic ignition module, and the coil is still external just as it always was. Your kick down switch wire is connected to the external coil not to the Pertronix. You are grounding out the ignition at the ignition coil ahead of the Pertronix ignition module, ahead of the distributor. Those seem to work ok with the overdrive kick down switches, because the coil will absorb most of the voltage spike. This setup seems to work well with the Pertonix negative ground applications.

The positive ground Pertronix electronic ignition applications seem to have some issues with the kick down switch in the circuit. The manufacturer is not sure why there is a difference. Most positive ground applications work ok, however... a few do not. Something to be aware of.

I have talked to all of the aftermarket electronic ignition manufacturers and they are all telling me the same thing. We don't recommend grounding out the electronic ignition even for a brief time, because of the possible damage to the ignition modules from voltage spikes.

If it makes you feel any better we are not alone. Some boat transmissions also require a pause in the ignition the same as we do, to allow the boat transmission to shift from forward to reverse and from reverse to a forward gear. The reason was the same as for our overdrive transmission, so the transmission itself did not have to shift under load. Like our antique vehicles...those boats were manufactured when a contact point ignition was the standard.

So if you are thinking of adding of adding electronic ignition to your antique vehicle, you need to be aware of this issue with the Borg Warner overdrive transmissions.

If I figure out a good working solution I will let you know here.

UPDATE - 
It seem the best solution so far is to put a relay into the battery wire that powers the electronic ignition, that way you can safely interrupt the battery power going to the electronic ignition (before it gets there) so the overdrive can shift and you will not damage the module in your electronic ignition. This way should also not generate any voltage within the electronic ignition because everything is happening BEFORE the electronic ignition.

Our Antique Vehicles In Real Life...

Selective Memories...
Where did all of the antique vehicles go...?  "Why when I was growing up we "musta" had a dozen 1940 Ford Coupes in our neighborhood... " "and there were tons of old cars in my neighborhood back where I grew up...."

We have all had those conversations about all of the cool cars that lived in our neighborhood and how plentiful they were. So it would stand to reason that part of what we collect and drive today is a reminder of our youth and the cars we drove back then... or would have driven if we would have had the money.

The thing we often forget is that the antique vehicles we collect today were simply daily drivers back in the good o'l days. Not many people thought about their car being collectible someday.

When World War II came along many of the early "antique" vehicles from the teens and twenties, were simply worn out and had little or no value at the time, so they were donated to the metal scrap drives for the war effort, along with a few thousand porcelain advertising signs that we car collectors would die for today.

Because there were so many Model T and Model A Ford's built... despite the scrap drives, more than enough survived to be restored a generation later.

Also, many of our "antique vehicles" got destroyed or suffered major damage in wrecks. Just like today... when the damage was severe enough that it would cost more to repair the vehicle than it was worth at the time, it was scrapped. Some of the more rare ones we would no doubt try and save today, but back then, the repair costs exceeded their value.

So to put all of this in perspective, I am starting a page of car wrecks. Part of what makes our antique vehicles valuable is the number of survivors of a certain make and model. If every 1940 Ford Coupe ever built survived in drivable condition what would they be worth? Not much.

It would be the same for Ford vs Packard... for example. There were fewer Packards sold to begin with, as compared to Fords, in part because the Packards cost more... so they were not as affordable to as many buyers as compared to a Ford. That in part is what makes a Packard valuable today, there were fewer made resulting in fewer survivors. A Packard is also more expensive to restore today, as compared to a Ford or Chevrolet of the same era.

But when you are driving on the road with all makes and models, Packards got into wrecks just like the Fords and the Chevrolets, and all of the other brands on the road. Those wrecks took out quite a few cars expensive cars over the years.

And in some cases, there were no car owners involved when their cars got damaged. Being parked at the wrong place at the right time can also get your car destroyed without you even being there. I have a few examples here.

You can look at most of the following pictures and determine what happened to the antique vehicles and in some cases the drivers. We often forget that our collector cars were once daily drivers and were subject to the hazards of the road, which included bad weather, drunk drivers, speeding drivers, and those drivers who simply don't pay attention to the road.

So we should be thankful that we have plenty of antique vehicles available to us to restore, drive and enjoy. They did not all survive...




































































I was a tow truck driver in my former life and accidents like this are the most difficult to recover as there is little or no damage to the vehicle as it came to rest, but there is hardly any way it will not be damaged in the recovery process. Often times the insurance company fails to understand the situation and wants to blame the towing company for the damage to the vehicle after it is recovered.

More to come....