How do you get 12 volts to the coil

[Richard R.]

How do you get 12 volts to the coil on a 72 base 350. I am running the Petronix module and have some issues with the fuseable link breaking at the coil terminal. I have been advised to go around the fuseable link because it lowers the voltage to the coil for the old points setup. 12 volts at the coil should improve the performance and longevity of the Petronix unit. My guest ion is, we're do you tap into to get the 12 volts when the ignition switch is in the run position?

[Duke W.]

Re: How do you get 12 volts to the coil

12 volts at the coil should improve the performance and longevity of the Petronix unit. My guest ion is, we're do you tap into to get the 12 volts when the ignition switch is in the run position?

12V input (which is actually as much as 14.5V with the engine running) to an OE coil will likely fry it in short order. They're designed to operate on about 8 volts. I can't remember the last time someone had a problem with points. There are a lot of threads about problems with these electronic switches.

Duke

[Jim T.]

Re: How do you get 12 volts to the coil

Richard I have a GM crate engine in my 1970 that came with a HEI distributor requiring 12 volts. The factory wiring going to my 1970's original coil was a resister wiring reducing voltage to the coil. To connect 12 volts to the HEI I ran a new separate wire from inside the of my 70 from the fuse block through the firewall. There is a usable terminal available named IGN at the fuse block. Ran the new wire directly to the HEI from the IGN terminal. Only supplies power to the HEI when the ignition switch is used. No problems with this procedure since the early 90's. My original coil is not used with the HEI which was first available with 1975 Corvettes.

[Stuart F.]

Re: How do you get 12 volts to the coil

You didn't say which Pertronics unit you were using. If it is a II, and you are using a matching "Flamethrower" coil, then 12 volts is correct. If just a base unit or w/o a matching coil, then stick with the stock voltage drop input.

Stu Fox

[Dan A.]

Re: How do you get 12 volts to the coil

Just a suggestion, but if your 72 still has the idle solenoid wiring it is a switched 12 volt source.

[Frank D.]

Re: How do you get 12 volts to the coil

I have never heard of the problem you are describing with Pertronix vis a vis fusible link. Pertronix II and III units will operate with the full 12V; the III REQUIRES the full 12V - if you have a Flamethrower coil, dump it and get an MSD Blaster II; the Flamethrowers have a high failure rate.

I've installed dozens of Pertronix units and the failures I've seen are because somebody had a very early unit without all the protections, they used a dicey coil or else did a bad installation. They are Hall cells - you prob have 1/2 dozen of them in the new vehicles you drive.

And yes, every 3-4 months somebody has a points problem on the CF forum....sometimes a condensor problem.

[Michael W.]

Re: How do you get 12 volts to the coil

I think the OP means 'resistor wire'. There is no fusible link in that circuit.

[William F.]

Re: How do you get 12 volts to the coil

Pertronix web site has wiring diagrams for the various series. Basically you bypass the resistor. Again, must use a coil designed for 12V if your unit requires 12v.

[Larry M.]

Re: How do you get 12 volts to the coil

I think the OP means 'resistor wire'. There is no fusible link in that circuit.

Agree............resistance wire is all there is.

Larry

[William C.]

Re: How do you get 12 volts to the coil

The factory setup used a resistance wire in the wiring harness to drop the voltage to the dist/coil when engine was running. It was bypassed when starting by enabling a bypass wire from the solenoid to the coil.