Reply to "Installing Ford DuraSpark Module - Glenn C"

The only reason the MSD ignition requires a special "add-on box" for the tach is because of the multiple spark feature. The tach can be connected to the coil in the normal manner as long as the ignition does not have multiple sparks, like the DuraSpark modules.

Glenn I can scan & post a schematic of the DuraSpark module wiring this evening if you would like.

DuraSpark modules are identified by the color of the plastic wiring strain relief. The DuraSpark I modules with the red strain relief are a bit more sophisticated than the DuraSpark II versions, they require no ballast resistance in the coil circuit, which is a nice feature for custom installations. Instead of having a ballast resistance to limit current in the coil, the DuraSpark I with red strain relief adjusts current in the coil primary to control current in the secondary and is therefore capable of supplying a "healthier" spark. All DuraSpark modules are designed to sense when the motor is being cranked by the starter motor, and to retard the ignition timing during starting to make the motor easier to crank over. The last nice feature, the DuraSpark modules seem to have about a 20 year or 100,000+ mile life span.

They're a good "street" ignition module. On the other hand, the Ford dizzy is reliable, but not the most wonderful instrument, as it will scatter the ignition timing at around 6000 rpm & above, and the advance mechanism gets "sticky" with age. They are worn out and in need of an overhaul at 50,000 miles or sooner.

One last bit of info regarding Ford ignitions, a paper distributed by Ford in the '70s revealed the performance of the coil decreases with use (mileage). As the coil ages, performance at higher rpm worsens. On a vehicle with a high performance motor, replacement of the coil every couple of years (20,000 miles?) would be a good idea to insure power is not dropping off at high rpm. This information only pertains to Ford coils, aftermarket coils may be better or worse in this aspect.

cowboy from hell