Ford ballast resistor

[Mike K]

I am theorizing but I think the divers bell type dissy was adding to the erratic ignition issues. With the squat coil sitting on top of the dissy , it is in a terrible position, subject to the heat from the radiator . With the improved crab dissy setup , they located the coil away from the hot environment.

When I had the little 1941 11D truck , I was amazed at how it would start from cold on a almost dead flat battery, the motor would be barely turning over, but it would fire and start . The trouble appeared after the resistor had heated up , I used to stop on the roadside and by pass the resistor with a wire link , this bodge fix got me home more than once.

After fiddling around , I discovered that the Voltage reg. was set rather too high , lowering the Voltage setting really improved the ignition system reliability . lower Volts = less Current through that resistor and less heat.

[Jacques Reed]

Originally Posted by Mike Kelly

I am theorizing but I think the divers bell type dissy was adding to the erratic ignition issues. With the squat coil sitting on top of the dissy , it is in a terrible position, subject to the heat from the radiator . With the improved crab dissy setup , they located the coil away from the hot environment.

When I had the little 1941 11D truck , I was amazed at how it would start from cold on a almost dead flat battery, the motor would be barely turning over, but it would fire and start . The trouble appeared after the resistor had heated up , I used to stop on the roadside and by pass the resistor with a wire link , this bodge fix got me home more than once.

After fiddling around , I discovered that the Voltage reg. was set rather too high , lowering the Voltage setting really improved the ignition system reliability . lower Volts = less Current through that resistor and less heat.

Hi Mike,

That makes a lot of sense, Ford moving the coil from the divers bell distributor to above the block with the advent of the crab distributor. It has to be a lot cooler up there.

Your bypassing the resistor to start a hot engine is interesting too. I hadn't heard of that before but reading some of the info on hot rod and Ford Flathead V8 websites, that is not an uncommon fix/modification for improving the hot starting of these engines. Some even rig a permanent bypass switch to easily enable this function. All good I guess as long as you return the switch to the non-bypassed position after it starts!

Cheers,

[Rod Salter]

Quite a number of (12volt) starter solenoids have the extra terminal to bypass the ballast resistor on 'start'

I suggest a 6volt relay could be wired into service perhaps,

Early XL XP fords had the ballast resistor as a PINK wire buried in the wiring loom from the ignition switch to the coil
Also, an inline fuse for lights neatly bound inside the insulation tape in an inaccessible place up near the firewall

.