Ignition Issues

[Rangepony]

OK....I've been driving my 73 Roadrunner 340 auto everywhere and she left me on the road the other day dead as a hammer. The coil was too hot to touch. Got her home, replaced the coil with an Edelbrock HEI coil to match the distributor (picture) and she ran great! Only problem she dropped me again after about ten miles.....

When I put the new coil on I by-passed the ceramic block as I understand the HEI distributors like 12 volts firm, not the reduced amount. The coil that died on me the first time was a standard coil run through the ceramic block.......

Not sure what to do now....I've not had this problem before....

Do I hook the block back up with a higher rated coil or do I upgrade the whole system?

Signed,

Befuddled in Greensboro

 

[Sinitro]

No experience for the Edelbrock HEI coil...
Note many ignition problems surface when mixing various brands
for different ignition component such as ballast resistor, coil, distributor and ECU.
Each brand is designed with slightly different specs,
so IMHO best to keep everything matched..

Just my $0.02..

 

[PurpleBeeper]

Are you sure the 2nd coil is bad?

 

[Canadian1968]

I don't see an hei distributor .

I do see a orange mopar ecu on thr fire wall though

 

[Bird 426]

Not a stock dizzy either. So what system do you think that you have?

 

[hunt2elk]

Distributor looks like a Firecore?

 

[twecomm]

Agree with Canadian1968, you have the "Orange Box" Mopar electronic ECU on the firewall. I also would agree that does look like a Firecore brand distributor. I'm running one on my 383. I would try a stock coil and have the Ballast resistor in series like it was originally. You might want to measure some voltages. In a stock system, with ignition key switch in the "crank" position, both sides of the ballast resistor should have full battery volts. In the run position, the coil or the other side of the ballast should have about 2-3 volts less than full battery. Don't think you need upgrade anything. Make it like original is a good place to start.

 

[Sixpactogo]

It sounds like the classic Piss poor ground at the ECU to me. If you have a digital ohm meter, test between neg post on the battery and ECU case. I'm betting you get a high reading. Anything much over .5 ohm will cause the issues you are dealing with. Sitting alongside the road with a overheated coil and an open circuit on the transistor in the orange box until it cools down and lets you go for a while again.

 

[Lefty71]

Not sure what to do now....

Im no expert on what goes with what, but coils need to match up to whatever ignition or box you are running. Id be curious to know how you are sure the second coil is dead too.

In your shoes, id give a shout out to Halifaxhops, follow his advice, and give him a few bucks if he has the parts you need.

 

[Geoff 2]

I am not surprised the coil is 'hot'. Mounted on a hot engine is going to cook the 'coil' & reduce the spark output. A most stupid idea from many manufacturers. You will need to swap the coil to see if it has failed.

As to the BEST coil, need to know more about the type of dist.

 

[Kern Dog]

I am not surprised the coil is 'hot'. Mounted on a hot engine is going to cook the 'coil' & reduce the spark output.

Let's see, one can trust a factory that built millions of cars that way OR we can do it your way.....

 

[Rangepony]

Are you sure the 2nd coil is bad?

I'm not sure...After I pulled the car out of the middle of my driveway (we were going to lunch with my dad) it was my snap thought as it acted just like it did when she left me on the road....All the comment here are great.....I'll do some more playing with her today. Never head of a Firecore but it looked like an HEI distributor....I guess it like a Pertronics? I'll try the original set up today and see how it goes

 

[Bird 426]

It also has the appearance of an FBO dizzy, but the FBO bypasses the ballast and has a 1.5 ohm coil.

 

[Rangepony]

I went in and re-wired everything back to original through the block and she fired right up....maybe the direct 12v overwhelmed the ECU? Anyway, I drove her for 30 minutes, 70 mph on the highway and never a giggle. Got home and laid a hand on the coil (picture) and it was not as hot as the engine which I would say is a good sign.....many thanks for all the help!!!

Oh.....now the headlights decided not to work.....I hate old cars.....

 

[Kern Dog]

I don't hate old cars at all.