55 ballast resistor

[Keith Tholin]

I am having starting problems with my 55 and I wonder if it could be the ballast resistor. First of all, I have reinstalled the wiring harness after a year of restoring the interior. The wiring diagrams aren't specific with regard to the ignition switch. There are two leads from the ignition switch, one brown and one green. It appears as if the green lead bypasses the ballast and leads directly to the positive terminal on the coil. The brown lead terminates into the ballast which then leads out of the resistor with the green to the coil. Am I correct in assuming the green lead should be connected to the "ignition 2" post on the starter switch (ie when fully turned to the start position) and the brown lead connected to the "ignition 1" position (in the normal running position on the starter switch)?

Secondly, I have been able to start and run the car, but now it won't start and there is no spark. The ballast resistor is very hot after cranking and it appears there might be a slight crack in the porcelin underneath. Could the ballast resistor be shot and this causing the starting problem?

[Roy Braatz]

Re: 55 ballast resistor

Keith I have the original NOS main harness in my 55 haveing metal connecter for the dash lights, not plastic like the repro's which also have different color wires then original. On my ballaster one side has a blue wire and other side green, both coming from the main harness. the same green wire has a split wire also going to the coil static resister ( original shielding)at one end and at the other end a short shielded wire going to the coil.Then a black wire going to the points.At the key the blue and green wire are in the same connecter and yellow is the starter wire going to the starter solinod which has only one small post and the brown wire going to the positive large post .But your ballaster wire now may be broken.You can jump a wire from the hot side,blue wire stright to the coil to see if the car starts, and if so the ballister is shot.

[Bernard M.]

Re: 55 ballast resistor

Keith, I don't have a '55 or any wiring to refer to, but it seems your ballast resistor should not be hot after cranking. The object of having the two wires is to allow current to shunt the ballast resistor during cranking. It may well get hot if the ignition is left in the on (not start) position, whether or not the engine is running. Are you certain how the switch positions relate to the terminals?

[Dave Suesz]

I beg to differ...

The ballast resistor gets quite warm to the touch during normal operation. I guess that's why it's ceramic instead of plastic. My ballast resistor died about twelve years ago. I found a very clean original on a '55 Chevy in a yard. One difference- the back of the Chevy unit was open, allowing heat to radiate, while the 'Vette unit has a ceramic back cover, which reduces the heat on the fiberglass firewall. The brown supply wire and the wiper motor wire attach on the rearward end, and the green ignition wire attaches on the engine end. I filled in the backside of the Chevy unit with muffler sealant, and it has worked perfectly ever since. These wire colors are on the excellent 'Lectric Limited harness I installed, and match the colors on the original harness, which I still have.

[Roy Braatz]

Re: I beg to differ...

Well I must have had many miss-fits over the last 35 years because every ballaster I'v seen on my Corvettes 55-57 had the open back ballasters were you can SEE the wire like the car verson.

[Bernard M.]

Re: I beg to differ...

David, I don't think we differ. You simply restated what I said in different words. The resistor gets hot during NORMAL OPERATION. But when the ignition switch is in the START position the resistor is shunted, and virtually no current passes through it. Therefore, CRANKING the engine does not cause the resistor to get hot. The resistor will get hot with the ignition switch in the ON position, even if the engine is not running, but does not get hot due to cranking the engine.

[Dave Suesz]

Gotcha *NM*

[Dave Suesz]

I can email you a photo...

I kept the original, even though it was dead. Pity I can't post it here.

[Dave Suesz]

Roy, you have mail. *NM*