What you need:
Duraspark II distributor
New plug wires
New or donor coil
Mr. Gasket recurve kit #925D
Assortment of tools including electrical tools
Assortment of cleaning utensils
Dial back timing light
Start by finding a 1976 or later donor car with the Duraspark II, or you can buy it new/rebuilt. When you pull the distributor also take the coil (If using the donor coil make sure to get the horse shoe connector as well, plug wires, plugs, as much wire as you possibly can. I got mine from a 78 Fairmont, the recycler I used already pulled it and didn’t have the control module or wiring harness available. I bought a new Dyna module from Classic Inlines in place of the stock 78 module. I highly recommend reading other articles on this project.Classic Inlines DSII Swap Dramatically better MPG with the DSII Ford DSII Recurve Duraspark II DSII Diagram
Here is a picture of my restored Duraspark, painted red. As you disassemble the distributor ensure that all
Parts are clean, move freely, and that the bushing is in good condition.
Remove the distributor cap base to expose the breaker plate
Next remove the vacuum canister from the distributor. After removing the two screws the arm should just
slide off the pin.
Remove the reluctor by prying upward with two screw drivers, making sure the blades are against the base not the teeth. If this doesn’t work for you, it didn’t work for me, you can try the next step. When pulling the reluctor be careful not to lose the pin holding it in place.
I had to sacrifice an allen wrench by cutting off the arm and using it as a punch to push the pin down
through the reluctor.
Remove the top half of the breaker plate and clean under it, reassemble.
Remove the two screws holding down the breaker plate and remove it exposing the mechanical advance
Toughly clean all moving parts and ensure that that operate easily. Replace the lighter spring with one of the
Springs from the Mr. Gasket Recurve Kit # 925D, I got my from Jegs, then move the arm from the heavier spring
3/32 of an inch in towards center.
After replacing the breaker plate replace the reluctor and pin, I had to use the allen wrench again to push the
Pin into place. After the pin is in place use a spark plug socket to tap the reluctor down into place.
Reverse the disassembly steps and completely reassemble the distributor.
Out with the old and in with the new. First line up the firing arm with the number one plug wire, this can be done
by manually rotating the engine. First ensure the battery is disconnected and the transmission is in park or neutral.
Now rotate the fan blade to rotate the engine. You may have to push down on the belt in order to create enough
friction to rotate the engine. Once done the firing arm should be in about the 6 o’clock position. Now remove the
bolt and hold down for the distributor on right side. As you pull the distributor out the firing arm will move clockwise
note its final position.
Before you drop the DSII in set it’s arm to the approximate spot the Load-o-Matic arm ended when you pulled it. As
you drop it in the arm should move counter clockwise down to the 6 o’clock position. Replace and lightly tighten
the distributor hold down.
Mount everything in a safe cool location. The drivers side fender wall in front of the shock tower is a popular spot.
Here’s a rough sketched wiring diagram for my 67 mustang. First lets cover some of the basics behind the wiring.
The solenoid is a switch that powers both the starter and a full 12v to the coil. The switch is closed by sending 12v
to the “S” terminal, so when you turn the ignition to “start” you close that switch sending power to the start and
the coil. Because the points could only handle 6v without burning up Ford installed a pink resistor wire, more on
that latter. When starting the engine the coil needed a full 12v, in order to do that Ford bypassed the resistor
while cranking. When the solenoid closes it also sends 12v to the “I” terminal, through the brown wire, and up through
the red wire to the coil. While the engine is running the solenoid is open, 6v is sent through the resistor, through the
red wire and to the coil. It also back feeds 6v to the “I” terminal. It is important that you remove this back feed
other wise you risk wearing out the solenoid sending 12v back through the blue wire burning wires under the dash.
So now that we have an idea of how the old system worked let wire our new setup. First let ensure our battery is
disconnected and its safe to work. Next pull the ignition out so you can work with it. I will not detail this step
because of the many different setups there are. Once out locate your pink resistor wire, keep in mind after
40+ years and multiple paint jobs it might not be so pink. Luckily for me mine was very well marked. Cut or
Remove the pink wire, if you cut it make sure to properly end the wire so it doesn’t short anything out. Now you
can either connect to a 12v ignition source to the coil or splice into a 12v wire. Run this new wire, yellow
in my diagram, through the fire wall and to the coil, if needed install the resistor that came with Dyna Module kit.
Keep in mind those using other modules may not need this resistor. Remove and cut the old wire running to the
Coil and remove the brown wire coming off the “I” terminal, again making sure the wires are not exposed.
Now lets test it all, you will need a helper. With the battery connected turn the ignition to the run position.
Test to see that your getting 12v to the “+” terminal on the coil. Now disconnect the wire going to the starter from the
Solenoid. Have your helper hold the ignition in the start position. Again make sure your getting 12v to both
the “+” terminal on the coil as well as the “I” terminal on the solenoid. If not you car is worthless, if that’s the
case I would be happy to buy it from you for next to nothing. If that won’t work for you rework it and retest.
If you still can’t figure it out that’s what the forum is for.
The colors I refer to are in my diagram, actual wire colors in your vehicle may vary.
Reconnect everything and put it all back together, remember your new duraspark needs different wires. Use
Now that you have everything wired and put back together lets get ready to fire her up. When choosing plug wires for your new DSII remember its needs a different style wires. The old caps are smaller and have well type connections whereas the new cap is much larger and has post type connections. Use Either the ones from the donor or you can get a set from your local parts store just ask for the wires from The same vehicle and year you pulled the parts from, a mid 70’s Fairmont or something. Now’s also a good Time to make sure you have a step colder than stock plugs gapped at .045 - .055, start at the lower number drive it and decide if you can go bigger. When setting your advance you may need some one to crank the engine over while you adjust the distributor until you can get it in the ballpark. Set your advance either using timing light or even better a vacuum gauge. This can be done by connect a vacuum gauge to a manifold source, disconnecting the vacuum advance and plug its source starting the engine and rotating the distributor clockwise or counter clockwise (counter clockwise for more advance, clockwise for less) until you get the highest steady vacuum reading, then back off 1-2 inHg. Shut down the engine, tighten down the distributor hold down bolt and recheck it to make sure it didn’t move while tightening.
Now to go one step further, track the new curve on the DSII. You will need a tachometer, dial back timing
light, graph paper, and a friend. First note what your initial advance was and what RPM’s you were running.
Next start the motor and check the timing with the vacuum advance disconnect connected at idle. Increase engine
Speed by 500 RPM increments noting the total combined advance at each step. You may need to dial back the
timing light to keep the timing notch within the numbers. Continue to increase engine speed until about
3000 RPM. The goal is about 32-35 degree’s of total advance in before 3000 RPM.
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