christineman

I've got. 392 with mad ignition. I can let it run for about 1/2 hour then I loose all spark till it cools off. The coil gets so hot u can't touch it. Change the coil and she runs for another 1/2 hour.. Any suggestions????

bremereric

I would say you have a short in your primary ignition system somewhere. And is it mad ignition or msd ignition?

PK1

You have it wired wrong or there is an issue with the wiring going to it. You need a volt meter and start checking the wires going to it.

Be careful with an over heating coil. They CAN explode. I have had it happen and fortunately the hood was closed. The oil is like a gel and melted numerous components inside the engine compartment.

Archer

C -

Just curious, does your rig require a ballast resistor and do you have one (that's not by-passed)???

Archer

440roadrunner

Question numba ONE What is "mad" ignition?

Question numba TEU What are you using for coils? That is, are these stock factory 12V coils such as used in 60's/ 70's Mopars, or UN known coils that you drug out tfo the junk box, what?

Question numba Tha REE Are you using a coil resistor/ ballast resistor? If so, what are they, IE where did you get them?

Both original GM/ Ferd/ Mopar breaker points systems, AND the Mopar ECU system operates under the same general guidelines, AS ORIGINALLY conceived.

When starting, the battery is "loaded down" below 12V so you need something to prop up the starting spark

When running, the system is NOT 12v, but the charging voltage, closer to 14V

So you need a "ballast" resistor to even out coil voltage.

In earlier Ferd/ GM/ Mopar coil systems, when starting, the ballast is BYPASSED to provide hotter voltage to the coil for starting, dropping back through the coil / ballast resistor for "run."

The coil "load" presented to the ballast CHANGES with engine RPM, l because the RPM changes the effective duty cycle. The purpose of a ballast is to CHANGE RESISTANCE WITH HEAT and help to "even out" these changes.

So WITH a properly MATCHED coil and ballast in place------


Key on, engine off--- voltage at the "key side" of the ballast should be within a VERY few tenths of a volt as the same as the battery voltage BUT............

The voltage at the coil + WITH THE POINTS CLOSED will be VERY LOW, sometimes not more than 4-5V, and many times 6--8V

WITH the engine idling, voltage AT THE KEY SIDE of the ballast should again be same as battery, and with the engine running fast enough to bring the charging voltage up to "normal" this should be 13.8--14.2V

On the COIL side of the ballast, voltage "running" will vary from around 7---10V or sometimes as high as 11-12

THE POINT to all this is that MOST coils you run across are designed for the proper ballast resistor. On many Ferd/ GM legacy cars, this resistor is a special resistance wire in the harness, as opposed to the ceramic block style that Mopar uses.

You need to have a coil and resistor combo that is meant for each other.

There are 6v coils for older 6v cars and SOME of these do, some do not use a resistor. Early Ferds sometimes used a resistor on 6V coils

There are 12v systems, most coils requiring a ballast as mentioned.

There are 12V systems, HIGH PERFORMANCE coils, which require a DIFFERENT ballast than factory coils. SOME performance coils (The old Mallory rectangular coil comes to mind) uses TWO ballasts IN SERIES

There are 12V systems which do NOT use a ballast, such as many tractors and other industrial equipment. These coils are MEANT to operate with NO ballast right off the 12--14V system.

Gorts 5th

boy thats for sure use exactly wat the ignition manufacture recommends i had the same problem
i use mallory and use exactly wat they recommend
also check to make sure ur electrical systems not shorting or grounding through the coil check your engine and chassie grounds

TVLynn

Change the condenser! as a start to see if it fixes the problem