Duraspark II Conversion

[Dragon]

A crossed wire???? I did one day and had the same symptoms.

[BobbyFord]

Check the timing. What carb are you running?

[f1shermun]

The timing is set at 10btdc and it has the motorcraft 2100 carb. I will double check to see if it is cross wired. I hope that it is as simple as a crossed wire.

[Dragon]

Every time an autolite backfires and even worse if the choke is closed it will blow the power valve.

[f1shermun]

replaced the power valve and I still have the same problem.

[FORDification]

Backfiring is almost always the result of faulty timing. Maybe the distributor holddown bolt has vibrated loose allowing the distributor to move, or the rubber portion of the harmonic balancer has slipped, causing an inaccurate reading when setting the timing. Maybe it's simply that the plug wires were set up in an incorrect firing order or the timing plate in the distributor is sticking. You'll need to check all these things out.

[f1shermun]

how do I check for a slipped balancer or a sticking timing plate?

[Dragon]

Timing plate remove the dizzy cap and turn the rotor. The mechanical advance should just turn and spring back. The vacuum advance you can supply vacuum and watch the plate move or remove the 2 mounting screws and leave teh inside hooked up and move the unit and see if it moves easily.

The timing ring will have really bad rubber if it slips it will look like it is coming out or is torn up. I have had fast revving light flywheel race FEs slip the ring but I have never seen a street motor that way.

[Thunderfoot]

Could also be a bad module...

[f1shermun]

I took my time rebuilding the carb. I soaked it over night in berrymans carb cleaner. That stuff ate the rubber mat on my work bench. It will not dissolve rust though. I used paint sprayer brushes and torch tip cleaners to work all of the rust out of the little holes. I was amazed at the amount of crud that came out of the boosters. I also replaced the fuel filter and added another inline filter before the carb.

[f1shermun]

following Dragons advice, I checked the movement of the vacuum advance. I had the stop adjusted almost completely out. Luckily I live at the base of a HUGE hill. Now the rattle is gone when I gas it under a load. Thanks guys!

Is there a difference in the spark plugs i should use since I upgraded to duraspark ignition? Do you guys have any suggestions?

[Dragon]

I found that Autolite 45s where usually gapped for Duraspark not points when you buy them. Ford only changed the gap when they went from points to Duraspark. Of course that means you need a Duraspark coil or a hotter one too.

[Dean]

I upgraded my 1968 f250 10 years ago useing a 1976 DS1 distributor that was used in the F350 391 engin and the DS2 Box fron a 1977 and up.
I used the origonal plus resistor coil wire to a DS2 coil . It is nessary to add a non reristor wire from the Ignition switch same terminal as where the resirtor wire is fed going to the red run wire on
the DS2 box . The white wire on the box must recieve 12v from the i starter solenoid terminal while starting. It has been trouble free. Dean

[Dragon]

Honestly in my years with Ford only 3 Durasparks ever failed that I saw and my Dad's 79 F150 had a failure of the Dizzy internal module.