1970 roadrunner stalling

[MO roadrunner]

Have a 1970 roadrunner with 383, running electronic ignition with accel coil, wouldn't start last week, ran checks on electronic control box and ended up putting old ballast resister on that I carried for a spare, and it fires right up. Took it for a drive last week and it keep wanting to stall out after about 15 miles, got it back home, dies pulling into garage, does restart after longer than normal cranking. Ballast resister feels extremely hot. This morning starts right up, meter shows charging 19 volts, electrical is not my best subject so I'm asking , do you think my voltage reg needs replaced or are there other issues to be checked ?

 

[Sixpactogo]

First thing I would do is take my digital Ohm meter and verify a good case ground at the CPU and voltage regulator. (less than .05 ohms) Ground reference is very important. 19 volts is way too high. Should be around 14 V. If you have good grounds at both units, you more than likely need to replace the voltage regulator. I suspect your CPU is getting hot from either a bad ground or the 19 volts is overheating it.

 

[R413]

19 volts will damage many electrical things, fix it first.

The negative battery cable should have a 14-16 gauge wire off of the battery end that bolts to the core support to ground the body. If not there then add one there or from the rear of the engine to the firewall bolt for the voltage regulator.

The blue wire at the voltage regulator needs to have battery voltage or it will go full charge.

the voltage regulator needs to be grounded.

 

[MO roadrunner]

First thing I would do is take my digital Ohm meter and verify a good case ground at the CPU and voltage regulator. (less than .05 ohms) Ground reference is very important. 19 volts is way too high. Should be around 14 V. If you have good grounds at both units, you more than likely need to replace the voltage regulator. I suspect your CPU is getting hot from either a bad ground or the 19 volts is overheating it.

Will check ground on regulator, I had trouble with CPU in the past and made sure it now has good ground. Car was repainted recently so I suspect I may need to scrap off a little paint behind the regulator. thanks for the info.

 

[Sixpactogo]

Will check ground on regulator, I had trouble with CPU in the past and made sure it now has good ground. Car was repainted recently so I suspect I may need to scrap off a little paint behind the regulator. thanks for the info.

When you re-install it, put a star washer between the firewall and regulator. Do the same with the CPU. It is good insurance since you can't have too good of a ground. It may solve all of the electrical issues you are having. Good Luck!

 

[R413]

Put the star washer under the bolt head.

Please don’t scrape any paint off the firewall. The car factories don’t do that and they build millions of cars per year.

Make sure there is a ground wire to the body. Post #3

 

[Sinitro]

On a 70 RR the voltage regulator is mounted on a metal bracket... In my installs I add a ground braid strap from the regulator bracket to one of the bolts holding down the end of the valley pan. Here is pix of the strap available at any auto parts place...

Just my $0.02...