My 63 max wedge clone has the over the counter Mopar electronic distributor that has the mechanical tach drive, no vac advance. The ignition box is a light gold color. I currently have an Accel 8140 coil. Wanting to replace the coil. What should I get? It's in a laying horizontal position, I was told that's not good for oil filled???
Looking up ign boxes I see one that looks same color, isted as 72-74, 76 A B body.I'm sure it's just a stock type box
The current Accel 8140 with a 1.4 ohm primary resistance is fine for a Chrysler stock to a moderate level Direct Connection/Mopar Performance electronic control unit (ECU), depending on the ballast resistor used. With this coil primary resistance, a ballast resistor of 0.5 - 1.5 ohms at 70-80 degrees Fahrenheit should be used.
The Chrysler 1960 - 1979 production coil primary resistance at 70-80 degrees Fahrenheit measures 1.6 - 1.79 ohms for the Prestolite 2444242 type coil and 1.34 - 1.55 ohms for the Essex/Echlin 2444241 type coil (part numbers 2495531 and 2084847). The Chrysler ignition ballast resistor used in the 1960s through 1972 for point systems measures 0.5 - 0.6 ohms at 70-80 degrees Fahrenheit and has specific, expected thermal design properties. The resistance of the compensating side of a dual ballast resistor used from late 1971 (some) through mid 1975 electronic ignition remained the same at 0.5 - 0.6 ohms but changed to 1.25 ohms from mid 1975 through 1979. WIth the change to the “4-pin” ECU in 1980, the single ballast resistor remained at 1.25 ohms.
A stock Chrysler ECU for a “72-74, 76 A B body” application covers several different, but interchangeable ECUs as follows:
- 3656127: For 1972 400 & 440 HP manual transmission, engine speed limited. Black case, red heat sink. 5-pin.
- 3656128: For 1972 340 manual transmission, engine speed limited. Black case, blue heat sink. 5-pin.
- 3656900: For 1973 All with black case with white dot, gold heat sink. 5-pin.
- 3755550: For early 1974 All with black case, gold heat sink. 5-pin.
- 3874020: For late 1974 through 1979 All with black case, gold heat sink. 5-pin.
A light gold color sounds like an aftermarket ECU which would replace the foregoing ECUs as a 5-pin or 4-pin unit. If you have a single, two terminal, ballast resistor, it is a 4-pin ECU. With a dual, four terminal, ballast resistor, it could be either a 4-pin or 5-pin ECU. If your ECU has a black finned heatsink, it may be the Direct Connection/Mopar Performance P4120600 ECU, which will work, but depending on the situation has some other component considerations.
Factory ignition coils are oil filled and were mounted horizontally from the 1960s into the 1980s. Operating a factory coil, or an Accel 8140 made 20+ years ago, will not pose a problem for the coil. If the coil is still healthy there is no need to replace it if the rest of the system remains the same. Modern oil filled coils may not behave the same, and some do list advisement against horizontal mounting.
The coil and other components for direct current limiting are based on the resulting cumulative resistance of the primary circuit. The cumulative resistance of the primary circuit including the ballast resistor, the coil primary winding, the wiring, the connections, and the effective junction resistance of the switching transistor or contact point resistance, should be such that the direct current (neglecting dynamic impedance factors) is less than or equal to the capacity of the series connected components, under the applied primary voltage. Depending on the applied voltage, primary current should be kept at four to six amps, with spikes less than 10 amps for production ECUs, or three to four amps with spikes less than six amps for production contact point sets.
For estimating purposes, the coil and ballast resistor are the primary resistances to consider. With good wiring and connections, their resistance is negligible. For these same purposes, the effective resistance and voltage drop across the transistor for an ECU, or the resistance of healthy contact points, in a point contact system, can be considered to be zero.
For a coil with primary resistance of ~1.5 ohms, use a ballast resistor of 0.5 - 1.5 ohms to keep direct current resistance at a point to limit coil and ECU, or points, current as previously described. If replacing the 8140 with a similar coil of similar primary resistance, use a ballast resistor resistance of 0.5 - 1.5 ohms at 70-80 degrees Fahrenheit. The lower resistance can yield a little more spark energy than the higher resistance.
MY Accel coil has 1.4 ohm pri and 9,9k sec. The MSD has half as much ohms, .7 pri, 4.5k sec. Is this only a concern when you have points?
The current through the coil and ECU switching transistor, or coil and points, is a concern for both. Select the coil primary resistance and the ballast resistance to keep the direct current to the same levels as described earlier. In the case of a 0.7 ohm primary resistance coil, to keep ECU transistor current to a reasonable level, use a ballast resistance of 1.0 - 1.5 ohms. For a high performance ECU, such as the P4120600, higher primary current can be tolerated. For a points system, a little higher resistance will be more friendly to point life. A coil such as the MSD 8202, with the 0.7 ohm primary resistance, can handle higher current levels, but the ECU, or points, are the limiting factor in primary circuit current.
