71 distributor wiring

[Chas Henderson #28127]

I asked a corvette magazine this question and got nothing for an answer. My 71 270HP 350 Auto coupe, according to the AIM manual and the GM service manual, the distributor wire should be hooked up to the positive side of the coil NOT the negative side of the coil; is this correct and why? The car has a negative ground for the battery, so why would the distributor be hooked up to the positive side of the coil? Has anyone ever noticed this before? Also, I have a pointless ignition system that I want to install; I also bought the more powerful coil, if I hook it up the way the book instructs, will this damage the distributor? Finally, I have noticed that in other service manuals, suchs as Haynes Manual, that the coil is hooked up to the negative side for my 350, is this just an error on GM's part, or the other manual's error? It seems incredible to me that both the GM and AIMs manuals would be wrong?

[John H.]

Re: 71 distributor wiring

Chas -

If you have a point distributor, the black primary wire from the distributor goes to the negative (-) terminal on the coil; the positive (+) terminal is for the power input from the ignition switch, either through a ballast resistor or a resistance wire; that (+) terminal should also have a yellow wire on it from the "R" terminal on the starter solenoid, which provides a full 12 volts when cranking. The 1971 factory wiring diagram is wrong - it shows the distrbutor primary wire going to the (+) terminal instead of the (-) terminal.

[John H.]

Re: 71 distributor wiring

Chas -

Follow the manufacturer's instructions for whatever pointless system you install, with particular attention to the power feed for aftermarket coils; some want a full 12 volts, and some want the same resistance-reduced voltage your stock coil requires. In any event, ignore the factory/A.I.M. '71 wiring diagram for the coil - it's shown backwards.