c3 no spark

[Ty T.]

Looking for a little help with a 66 I recently bought. It wouldn't start today, and after a little checking I found I had no spark. With the key on,there was .68 volt at the coil and the same measurement at both sides of the ballast resistor. It is a transistor ignition car. There has been some "bubba like" rewiring going on and an aftermarket Mallory breakerless distributor has been added. Up to today it has run fine though. I'm thinking maybe a problem with the transistor ignition. Any way to check it or any other ideas? Thanks for your input.
Ty Truax

[Jack H.]

Re: c3 no spark

Very confusing post... TI is the common term used for the factory original, optional, solid state ignition. There was no ballast resistor used with this system.

Then, along comes a modern, aftermarket Mallory ignition system and voltage readings at the car's ballast resistor. Typically, the older aftermarket solid state ignition systems are wired in to eliminate the ballast resistor as there are no points to 'burn' and the switching modules need a full 12 VDC to properly power them.

From, what you say, I'll take a stab... You don't have anything stock in the way of an ignition system and the car's running off the aftermarket Mallory. Next, it 'was' running OK, but after some period of time it isn't. My wild stab is this:

Letting the car sit, the battery has discharged and has fallen low enough that there's insufficient supply voltage to power up the Mallory system. Try putting the battery on a charger and giving it another start attempt. One caution: some of these after market solid state ignition systems don't tolerate well being jump started (voltage/current surges associated with splicing in another car's electrical system can burn them out), so bring your battery back to full charge nice and slowly...

[Jim T.]

Re: c3 no spark

I have a Mallory breakerless ignition system that I installed in my 70 about 1974. Still have it, but not in the car. It lasted a couple years and then just like your 66 now, went to start it one morning and it would not start. Pulled the distributor removed the Mallory unit, installed the conventional points system. It started immediately and have continued with just using the realiable conventional points system. The Mallory system I bought was the Unilight system. If your Mallory breakerless distributor does not have a vacuum advance unit you could improve the performance returning to a tach drive original advance curve conventional points type distributor.