Distro Ignition Q's

[Wayne G.]

On a dual point distro, is the ballast actually filtering the power to the + side of the coil? Or is the feed wire acting as the resistor? If so what wire the short lead from the coil to the resistor? I am speaking specifically of a 60 FI car, but I have read different setups on other years.

The question at hand is how does one tell or check that the resistance is correct. (reading its important so one does not burn out the points) What is the spec? I am asking because I have looked at schematics and see were the green wire from the + side of the coil goes to the green sided wire from the generator, and the other side of the ballast is going to the wiper motor and ignition? Since current flows from + to - this sort of makes no sense? I power to the plus coming from the generator or from the wiper side?

I don't get the ballast use this way, its filtering the wiper motor? And the green short wire from the ballast to the coil + is the resistor? (as I have seen wires sold online that say they are resistor wires?)

Reason for the questions, is the FI is off the car, and she appears to have a Distro from a 62 and a coil, but the ballast is original as so is the generator. Should I follow the setup from the 62 Distro for dwell, points and wires. Or the 60 setup? I have not checked to see if the 2 are really all that different. Probably not, but I just want to make sure I am not frying the points with any wrong hookup or setup. I found the duals were set to 29 total Dwell and that did not match settings listed in the Service Shop manual covering the range of years for 283 motors. (yes it's a FI high perf setup but ) I checked each point one at a time one was at 19 not good, the other one way higher, so using the shop specs I set them at 29 each and that gave me about 34.9 and then I just backed each one down about .4 to get her at 34, made a hudge difference in idle and throttle response. It can be a hard task to tune when you have a mix of different components on a stock motor.

[Duke W.]

Re: Distro Ignition Q's

All C1s had a 0.3 ohm ballast as OE, and you can measure it with a sensitive ohmmeter. Measure it at room temperature because the resistance increases as it heats up from current flow.

As a general rule, the plus side of the coil is wired directly to the battery bypassing the ballast during cranking, and once the ignition switch is rotated back to the "on" position, voltage to the coil is routed through the ballast. You should be able to verify this with your schematic.

The 0.3 ohm ballast allows high primary current for greater spark energy, but it's tough on points, which is why GM began using the 1.8 ohm ballast as a running change on 250/300 HP engines in 1963 and all engines with point ignitions in 1965.

If you've experienced burned points, it might be a good idea to replace your OE 0.3 ohm ballast with a 1.8 ohm ballast.

Duke

[Wayne G.]

Re: Distro Ignition Q's

All C1s had a 0.3 ohm ballast as OE, and you can measure it with a sensitive ohmmeter. Measure it at room temperature because the resistance increases as it heats up from current flow.

As a general rule, the plus side of the coil is wired directly to the battery bypassing the ballast during cranking, and once the ignition switch is rotated back to the "on" position, voltage to the coil is routed through the ballast. You should be able to verify this with your schematic.

The 0.3 ohm ballast allows high primary current for greater spark energy, but it's tough on points, which is why GM began using the 1.8 ohm ballast as a running change on 250/300 HP engines in 1963 and all engines with point ignitions in 1965.

If you've experienced burned points, it might be a good idea to replace your OE 0.3 ohm ballast with a 1.8 ohm ballast.

Duke

Sweet explanation ! Thank you! I get it now - I missed the ignition switching, its not all that clear on the schematic. I will put on some new points and set them up and see what happens, the miss adjustment may have fried them... so the thinking here is the higher R value will provide less current over the point area? Less heat, less attack? Would think this would slow the quickness of the coil charging just a little? Can't see it really hurting all that much for normal driving... Maybe effect if racing or looking for every drop of top end power? Once again thanks - I see sparks now!

[Duke W.]

Re: Distro Ignition Q's

The higher the ballast resistance, the lower the steady state current.

But above about 2500 revs current in the primary circuit doesn't reach steady state due to coil inductance and the short duration that the points are closed.

Also, use a coil that's matched to the ballast resistor.

The higher the current the greater the current density, and too high current density can burn points.

So the worst conditions for points is cold weather and low speed.

Duke