ballast resistor question


http://209.208.111.198/Topic52640.aspx 		Print Topic | Close Window

By uncleaud - 15 Years Ago
Putting my 57 bird back togeather after a few years off the frame. All under the hood and the running gear is done and working. The dash is still out and the wire loom is hanging on the clips. Last weekend I put the switch back in so I could start it and get it off and on the hoist. Had some issues with stuck float and while I was starting and running to fix that, the resistor quit. Didn't think anything of it as it was old. Bypassed it and got everything running right. Last night I pluged in another one I had in the drawer (typical ceramic GM unit) started it up and everything worked fine. The resistor started smoking, I think it was from dust and being new (as in old but unused) but not sure. Before I get another new one from the Tbird suppliers thought I would ask what else would or might make one smoke. This one has run for 10 or 15 minutes and doesn't appear to get red, it just makes me nervous to have something that puts out smoke under the hood.
By bergmanj - 15 Years Ago
Uncleaud,

I don't know the specific resistance and wattage values; but, dropping resistors work by dissipating the "extra - unwanted" power as heat, some can become very hot to the touch.  IMHO, you're probably O. K., and probably right about dust/dirt/oils burning-off during its first use.  Electrical/electronics has been my area of professional expertise for about 45 years now - personally, I'd just try it for a while and make sure that it doesn't get red-hot; it will probably get hot enough to burn your fingers, though, that would be my expectation.

I hope that this information gives you a higher comfort level.

Regards,   JLB

By ejstith - 15 Years Ago
I think the stock one is 1.4 ohm. I just put a variable one on my '56 with a Mallory electronic module & MSD disributor. It is a .75-1.50 ohm. Got it from Summit.
By GREENBIRD56 - 15 Years Ago
E.J. - I had two of those Mallory "variable resistors" go "open" in a fairly short period of time. They are supposed to start out "cold' at .75 OHMs and go up as they warm up - which seemed like a darned good idea. Hot spark for starting cold ....but - they only worked a short time. I couldn't find any obvious reason at all.

MSD sells a .88 OHM ballast - fixed value - and since it was about halfway between the variable high and low - I decided to try it out. It has held up well - no unexpected failures.  

By ejstith - 15 Years Ago
Steve, how did you know the Mallory one went bad? Wouldn't run?
By GREENBIRD56 - 15 Years Ago
I have my car wired with the traditional Ford "jumper" around the ballast resistor - with a lead off the starter solenoid. When the resistor failed, the engine would fire in "start" - then shut off when the key went to "run".

An occasional "infancy failure" doesn't usually get my goat - but the second resistor failed in less time than the first. GRRRRR. The MSD part has never missed a lick - its just a fixed value, heavy duty resistor - .88 OHMs. 

UncleAud - When I brought my outfit home (a multi-hour trip on a 104° day) everything under the hood smoked. The power steering reservoir had been leaking since about 1960 - and the previous owner only knew how to add fluid. Even after I got most of it sopped up, the ballast resistor would smoke from the oil contamination. I took it off, opened the cover (it was the original Ford part) and washed it with petroleum ether (starting fluid) several times before it got replaced by the new ignition. There was smoke but never any fire.

By ejstith - 15 Years Ago
When I got my '56 it only had a one (small pole solenoid, the brown wire is just hangin' at both ends) and I wired it like the guy at Summit told me to so I don't guess I'd actually know if it quit working or not. Or maybe, according to your diagram, it may die.