Packard Forum Index » Pre-War (1899-1942)

Hi All,

It's been a while... I was curious if anyone could please tell me which end is the positive end on this coil? Please see the pictures. This is a 6V positive ground car and coil.

Thank you in advance,
Crin

Attach file:

---

  (264.39 KB)


  (264.26 KB)

bottom is to ignition switch, top to distributor.

Right, I had that part but which one is considered positive and which one is negative? The reason I ask is because I've converted the distributor to a Pertronix electronic ignition module and I don't know where to run the wires. I have attached the wiring diagram and unfortunately the coil shown has both terminals on top. Please see picture.

I think the positive terminal is the one that used to go to the points which are grounded (hence positive ground) and the connection on the bottom of the coil is the negative one - that's the one that goes to the ignition switch.

That's what I think but I wanted to run it by the forum to see if I'm right.

I'm also confused by the fact that the wire coming off the bottom of the coil goes to the ignition switch so according to the wiring diagram I should be able to connect both of the wires from the ignition module to the bottom of the coil. I hate wires ... lol ... help...

Thanks!
Crin

Attach file:

---

  (15.43 KB)

Crin,

The wiring picture from Pertronix should show the wire from the ignitor (electronic switch) going to the bottom of the coil, based on the coil in your car. The other wire from the ignitor will go to the ignition switch.

This way your ignition switch still controls the supply of power to your coil in the correct polarity.

Power has to go thru the ignitor before it gets to the coil, since the ignitor is the electronic replacement for your original points.

If you were to connect both wires from the ignitor to the same bottom terminal on the coil, power would always be on to the coil, as long as the ignition switch was on. The coil would not fire in sequence based on the distributor cam lobes and the engine would not run.

Hope this helps,

Dave

Your thoughts are correct. The terminal next to the HV output would be positive and the terminal on the base or bottom of the coil, negative.

Out of curiosity, have you verified the amount of voltage available at the coil -- particularly when cranking. There have been several reports that the 6v Pertronix is somewhat unreliable. One common factor even with the original ignition is the voltage drops so much when the starter is engaged that voltage to fire the spark is marginal if not completely inadequate. The Pertronix devices are much more sensitive to low voltage than a standard point ignition will be.

Hi,

I haven't but I have two distributors. One has the original points setup and the other has the Pertronix setup. I also did not modify the breaker plate of either distributor so if I run into trouble I can go back to my points. I actually reproduce a one piece breaker plate for this 662T distributor simply because I couldn't get myself to damage an original breaker plate. You can see it by clicking here.

I will give it a shot and carry the spare distributor with me just in case the Pertronix gives me trouble.

Thank you again for the help,
Crin

Just keep the voltage available to the coil and module in mind if it starts misfiring. Doesn't have to be only during cranking. If headlights and radio or some other heavy draw accessory is on and generator is adjusted low or cannot keep up with demand that current draw can also make the voltage drop too low particularly if wiring or connections are dirty or in less than perfect condition.

I believe the Pertronix uses TTL logic which needs a solid 5v supply and will only tolerate a very narrow range plus or minus that amount. With a 6.3 v supply in the car there is a limited amount of drop allowable before the regulator circuit cannot reliably produce the steady 5v the logic needs and ignition starts to act up. In the 12v module there is considerably more drop allowable before any issues so the most likely reason very few complaints have been posted about those units.

Just wanted to thank you all for the help. She fired right up and runs strong. A little tweaking of the timing and I'll be ready to drive.