C3 - 68 BB ignition coil questions

[Dale P.]

I have a few basic questions around the ignition coil on my BB. First, I just want to confirm that the (-) post goes to the distributor and that the (+) has the "power" connected to it. Secondly, what voltage should I see when trying to start the car ( I assume 12 volts - I actually see 9 V) and what should I see in the normal running position (I am seeing 6.5 volts) - which both seem a little low.

Now for the tricky question >> how many wires should be connected to the "voltage" side/ (+) side of the coil? My set up has two yellow wires tied together with a connect which is then connected to the coil. So where do these yellow wires come from?

[John H.]

Re: C3 - 68 BB ignition coil questions

Now for the tricky question >> how many wires should be connected to the "voltage" side/ (+) side of the coil? My set up has two yellow wires tied together with a connect which is then connected to the coil. So where do these yellow wires come from?

Dale -

You should have a yellow wire, and a cloth-wrapped wire crimped to a common U-shaped spade terminal connected to the (+) terminal on the coil. The cloth-wrapped wire is a special resistance wire (replaced the separate ballast resistor used on all pre-'68 Corvettes), and it comes from the ignition switch, through the bulkhead connector; it supplies continuous running power to the coil (about 7-8 volts). The yellow wire is the "bypass wire" - it comes from the small outboard "R" terminal on the starter solenoid, and supplies a full 12 volts to the coil only when the starter is cranking; when not cranking, there's no current in that wire at all.