Reply to "Parts needed to convert duraspark?"

The Duraspark I coil had a primary resistance of 0.7 ohms, a secondary resistance of 7.3K to 8.2K ohms, and had no ballast resistor in the supply to the coil, the module controlled & optimized the charging of the coil primary by adjusting dwell.

The standard solid state module utilized the same coil as the breaker point ignitions with 1.17 ohms primary resistance and 7.7K to 9.3K ohms secondary resistance. It used the same ballast resistance as a breaker point ignition too (1.30 to 1.40 ohms in 1973 & 1974; 1.25 to 1.35 ohms in 1975 & 1976). In 1977 the ballast resistance of the standard solid state ignition was reduced to 1.05 to 1.15 ohms, and the coil and module were upgraded to handle the additional current and heat. The distributor cap was replaced with the larger cap to prevent crossfire, and the module was given the designation Duraspark II.

Duraspark I Coils: Motorcraft #DG-316 or Standard Motor Products #FD-477 (0.70Ω primary winding resistance). If you installed a 49 state Duraspark II coil in a Duraspark I ignition it will work, I've done it. The module will still do its best to optimize charging of the coil primary by adjusting dwell, and although its ultimate performance will be compromised it should still be as good or better than the the 49 state (Duraspark II) ignition. A possible source for the Duraspark I coil would be a NAPA store rather than a "speed shop". If you buy a NAPA coil I suggest taking your VOM with you to the store & measuring the coil primary resistance at the counter, since electrical parts are not returnable. I'd appreciate knowing what you end up buying and the part number.

Since I dug my ignition books out, I did a little reading, Ford solid state ignition was first used in 1973 Lincoln Mark IV (equipped with 460 V8s); in 1974 use of the solid state ignition was expanded to include all California emission controlled vehicles with 200 or more cubic inches, and all 49 state cars with 400 or 460 V8s. The solid state ignition was used fleet wide beginning 1975.

-G