Bronco Forum - Full Size Ford Bronco Forum banner

1 - 6 of 6 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
I just bought a '78 F150 4x4 with a 351M yesterday morning. I drove it home (about 40 miles) and then to the DMV to get it tagged (10-12 miles each way) and on the way home, I went through the drivethrough at Wendy's (about 2 miles away from my house) to grab lunch and it stalled on my way out. I parked it, opened the hood and touched the coil and it was about 14,000 degrees!! So I ate my lunch and let it cool. About 15 minutes later I tried to start it and it fired right up and made it home without an issue.

So then I figured the coil must have been worn out, so I went to get a new one and installed it. Well that lasted about another 20 miles and it overheated.

So my question is, what is causing the coils to overheat?? Are these trucks supposed to have a ballist resistor in the coil circuit?
 

·
press ALT+F4
Joined
·
4,279 Posts
The stock coil doesn't need a ballast resistor. I've seen Accel Super Stock and other coils with too low of resistance that needed a ballast resistor to run without overheating.
 

·
Registered
Joined
·
455 Posts
......
So my question is, what is causing the coils to overheat?? Are these trucks supposed to have a ballist resistor in the coil circuit?
Yes they are. The 78's actually have a resistor wire that's located
under the dash coming off the ignition switch.

Your 78's coil is probably getting a full 12v feed off of some other source,
and that's what's causing it to heat up. You can get an aftermarket
ballast resistor and wire it into the coil circuit; that'll do the same as
a resistor wire and keep the coil cool.....
 

·
Registered
Joined
·
2 Posts
Discussion Starter #4
Thanks for the input!

I replaced the voltage regulator in case it was bad, cause I wasn't sure if it was causing the alternator to pump out too many volts and at the same time I went ahead and threw a resistor on the coil circuit. Not sure which fixed it, or if it was a combination of both, but its running fine again.
 

·
Registered
Joined
·
455 Posts
:thumbup
 
1 - 6 of 6 Posts
Top