Low voltage to ignition coil

[1969911T]

Started installing an MSD ignition in my stock 1969 911T, but waiting for new spark plug wires. Meanwhile, I did something wrong and it wonÂ’t start using the original parts. Points groundout OK, then get weak spark when checking the spark from the coil wire to ground. Checked voltage to coil 10.4 VDC. Battery voltage is 12.8 and the engine fuse panel, where the relays are is 12.5 volts(these wires are not switched).

So, it is pretty obvious that I am losing voltage at the ignition switch. Before I remove the switch, anyone has a similar problem and advice of where and what to check?

[Richy]

Probably a faulty relay for the ballast resister which will not be used with the MSD ignition . I hope you will be using an MSD coil .

[Jerry L]

Probably a faulty relay for the ballast resister which will not be used with the MSD ignition . I hope you will be using an MSD coil .

Richy, What is the difference in the MSD coil? I am aware of the needed wires but not sure on the coil, would appreciate the education. I have a late 65 912 with MSD and Bosch Blue coil I have been driving for 10 yrs, what am I leaving on the table?

Best Regards

[Richy]

Standard coils can damage Bosch CD units , so to be safe I would use all MSD components , but maybe not necessary .

[1969911T]

On the ignition switch are two 12 volt incoming wires(always powered). One spade terminal was loose. Crimped down the spades and went from 10.5 volts to 12.5 volts at the coil. So that seems to be my problem. When I plug the 12.5 volts onto the coil that is grounded through the points, the voltage drops to 11.5 volts, without starting the engine. Is this typical?

Richly, I do not think my 1969 car has a ballast resistor. What would it look like? Yes I have an MSD coil, but waiting for the new spark plug wires before installing.

[Jerry L]

Standard coils can damage Bosch CD units , so to be safe I would use all MSD components , but maybe not necessary .

Thank You, the 912 is stock kettering ignition with the addition of the MSD unit, I do have the Bosch Black "transformer" coil on the 71 w/ 3 pin CDI. Thanks was wondering if the msd unit needed something special from the msd coil that I was missing.

Best Regards