Duraspark Ignition Question

Just friday I was told that the correct coil for a duraspark has the risitor built into it. The wiring diagram I had gotten on line. Believe it or not my friends just went bad also and he called tech support and they helped him thru it. Ford Motorsport TEch Line.

Ron

Scott,

Duraspark modules are identified by the color of the plastic wire "strain relef" where the wires exit the aluminum module housing.

I have never run across a Duraspark module with a black strain relief (they all had black connectors). The Duraspark II modules I am familiar with all utilized a "ballast resistor" in the form of a resistance wire in the primary ignition circuit. Not the coil. It was part of the cars wiring harness.

The Duraspark I modules had a red strain relief and had no ballast resistance anywhere.

The Duraspark I coil had a primary resistance of 0.5 to 1.5 ohms in 1977, 0.71 to 0.77 ohms in 1978.

Duraspark II coils had a primary resistance of 1.0 to 2.0 ohms in 1977 and 1.13 to 1.23 ohms for 1978 and later.

The ballast resistance for Duraspark II systems was 0.7 to 1.7 ohms in 1977 and 1.05 to 1.15 ohms for 1978 and later.

This info should be good for Duraspark modules having strain reliefs in the following colors: red, blue, yellow, white, brown.

Modules with a green strain relief are pre-Duraspark modules installed in 1975 and 1976 vintage Ford autos.

The Duraspark I module is the most robust module, it produces the fattest spark. However the Duraspark II module with the white strain relief featured a "cranking retard" mode which is ideal for cars equipped with hot camshafts that rquire a lot of ignition advance at idle.

your friend on the DTBB

Hi George,

The part number on my ignition box is D4AZ-12A199-C. That number crosses to Motorcraft part number DY-157B. It has a black colored strain relief.

I found a site that lists most of the Duraspark ignition modules. On page 4 of their document you will see the (black "grommet" or strain relief) unit.

http://www.mitechignition.com/automotive.html
Click on "Control Modules"

I guess I will get out my ohm meter and see if I can find a resistor wire anywhere and if not I suppose I will add a ballast resistor.

Thanks for your help, Scott

Well Scott,

I'll be dammed. There was electronic ignition on '74 California cars, I can remember that much. I never stopped to consider what module they used, but I guess it had the black strain relief. The "D4" in the D4AZ part number decodes as 1974.

So I pulled out my books and here's what I learned:

The '73 - '74 vintage ignition was installed in some 460 V8 equipped Lincolns in 1973. In 1974 it was standard in the 49 state cars equipped with 400 or 460 V8s, and California cars equipped with 6 cylinder motors or any V8. In 1975 electronic ignition was installed in all Ford products, and the box with the green strain relief was introduced.

The ballast resistance for this module is 1.4 ohms; the primary resistance of the coil is 1.0 to 2.0 ohms, measured between the "bat" & "dec" terminals of the coil; the secondary resistance of the coil is 7K to 13K ohms, measured between either the "bat" OR "dec" terminal of the coil and the center tower.

your friend on the DTBB

Thanks George,

Sounds like missing the ballast resistor may be why my coil went bad. I will add it now...

-Scott