Engine Electrical Question

[David J.]

My '66 originally had the GM transistor ignition. I needed to switched to a breaker point system. At the time, it was recommended that I put a resistor on the firewall to go along with the non-transistor set up. Can anyone verify the necessity and reason for doing this? Thanks, as always, for your expertise.

Dave

[Wayne W.]

Re: Engine Electrical Question

You need it to cut down on the voltage at the coil.

[John H.]

Re: Engine Electrical Question

Can anyone verify the necessity and reason for doing this? Thanks, as always, for your expertise.

Dave

Without the ballast resistor in the circuit between the ignition feed and the coil, you'll eventually fry the coil, which is designed to operate continuously at 7-8 volts. The only time it sees 12 volts is when the starter is cranking, which engages the bypass circuit from the "R" terminal on the solenoid direct to the (+) coil terminal.

[David J.]

Re: Engine Electrical Question

John,

Thanks for the detailed reply. I guess my next question is why wasn't there one there when I was using the transistor ignition? Finally, can you give me some information on the correct resistor for this application? Thanks so much for your help. Dave

[Timothy B.]

Re: Engine Electrical Question

David,
On a transistor ignition there is a resistance wire that's part of the TI harness and it's purpose is to reduce voltage from the ignition switch to the amplifier. There is no resistor mounted on the firewall on TI. There is also another resistance wire to reduce voltage to the coil and this is either the + or - wire depending on year. I think 64-65 used negitive wire for resistance and it was changed in 66 to the + wire.

[David J.]

Re: Engine Electrical Question

Thanks, Tim. I really appreciate your time and expertise. Of course, this leads me to an additional question. When the breaker point distributor was put in, the resistor was simply spliced into the wire. Nothing else was modified. Since there are already resistance wires in the TI harness, has an additional problem been created by adding the resistor?

[Timothy B.]

Re: Engine Electrical Question

David,
The TI harness runs along the firewall and down the drivers fender from the distributor to the amplifier. Points type distributors did not have this harness so a resistor is mounted to the firewall for your 66. If you want to run a points distributor remove the TI harness, (it should unplug) and install the correcr resistor on the firewall.

The only wires you have to worry about is the pink from the ignition switch to resistor and out the other side of the resistor to the coil +. Then a pink from the starter solenoid to the coil +. Black wire from distributor goes to coil - and the car should run.

[David J.]

Re: Engine Electrical Question

Thanks, again, Tim. I am very appreciative. This is a great site!
Dave