My 73 Ranchero 500 (302) likes to shut down while driving. Then it will crank without a spark and not start for a few hours. Then, everything is fine again and she's in a good mood. Since I'm not much of a troubleshooter, I've just been replacing old parts and hoping to get lucky. So far, I've replaced the coil, points, condesor, cap, rotor, plugs, wires and carbuerator. What now?
One more important component in the ignition circuit is the ballast resistor for the ignition
coil. If your spark quits when your engine compartment gets warm, it might be failing.
Thermal expansion and contraction over the years can cause them to fail. If you have a
meter, you could check its' resistance when you are getting spark, and when you get
no spark, or you can test by substitution.
Throwing money at the issue is only making you poorer, you need to have the problem properly diagnosed.
If you are in the SoCal area, call Bill at Bill's Auto Repair in Orange (714-639-3410). He is the BEST darn mechanic around on older Fords. He does most of the work for the SoCal Galaxie club members, and has done work for me. I highly recommend him.
There are other factors to consider. One is the ballast resistor (wire) mentioned above, others could be a bad ignition switch or point plate..and etc.
The ballast resistor is actually a wire on these models. Ignition switch to coil.
There's two different ones listed for 1973 Ranchero's.
It's prolly the first one, but who knows after 34 years what's been swapped around?
D1AZ-12250-A .. Ignition Coil Ballast Resistor Assy (Motorcraft DY-84-A) #16 gauge wire / color code red with green stripes / 1.30 to 1.40 ohms / 60" long.
D7AZ-12250-A .. Ignition Coil Ballast Resistor Assy (Motorcraft DY-213) #16 gauge wire / color coded red / 49" long.
Last edited by NumberDummy; 12-18-2007 at 08:06 PM.
Thanks. I will attempt to locate that ballast resistor first. I'm not brave enough to try to drive this puppy all the way to Orange but if I'm in that area, I will definately go see Bill and let him know he's spoken highly of. I appreciate the help.