I have electronic ign that is acting up. How many volts are supposed to be coming to the key side of a duraspark coil? I'm getting 7.8 right now. I'm thinking it should be around 11 or 12 ( with the key off ) just like it is up by the box on the fender.

Anybody have any ideas? I can't think of any reason other than old wiring that I wouldn't get full volts to the hot side of the coil.

Thanks.

 

with the key off there should be no volts to the box or the coil if there is you have a bad switch the coil has a built in resistor so 6.5 to 8.00 volts is fine

 

The key side wire is a calibrated resistance wire. You should not have 12 volts. Like ford390gashog said, you're voltage sounds fine.

 

For duraspark wiring diagrams:
https://www.ford-trucks.com/forums/member.php?u=1811

 

I have problems as soon as you load the engine. It pops back and has no power. I've run the timing all over forward and back. The vacuum advance works, I have fuel pressure. Everything seems to be working like it should. I have a new ignition box, wires, plugs, cap, coil etc. I'm usually pretty good at finding things that are wrong, but this one has me stumped.

Any ideas?

 

set the ignition with a timing light to 8 to 12 degess btdc check the firing order

 

This sounds like a lack of fuel. I don't know what year this is, but if it has a carb, I would pull the top off the carb and unscrew the jets in the bottom of the bowel and see if they are clogged up with dirt. Also make sure you have two strong streams of fuel pouring into the carb throat when you move the throttle open.

If you can continualy pump the gas pedal, and it will surge forward and run ok, but as soon as you hold the gas pedal constant, it loses power, then I bet it is dirt in the main jets.

 

Carb is clean. I just went completely through it. It's an edelbrock 600.

Symptoms are it runs just fine till around 2800-3K rpm on the flats. Then as soon as you step on it, it falls flat. Sounds like it isn't getting any fuel at all. Then it will backfire through the carb. If you let off, it will pick up a little, but it plays heck passing 3500 rpm. As soon as you hit a hill or require any power out of it, it won't pull at all. Doesn't matter if I'm in 3rd or 4th gear. Gas tank has been taken off and cleaned. New filters, new pump. It's holding 5.5-6 psi of pressure right at the carb when this happens. I put in a new ignition box, new coil, new rotor. The wires all check out o.k. The plugs are fairly new. The vacuum advance is working. I timed it to 13 BTDC with total of 36 by 3500 rpm. It starts and responds well everything is fine till you need a little power. Then it's over. I can't find a vacuum leak, it holds around 14" at idle. It doesn't smoke or knock or anything like a slipped timing chain. So far I'm stumped. I've tried 3 different ignition boxes thinking I got a bad one. I even borrowed one I knew was good. I'm going to try a different carb just in case, but if that isn't it, then I have no idea what it could be.

Any ideas? My only other thought is that maybe the induction pickup in the distributor is going bad. Anybody ever have one act like this?

 

I would be curious as to what the outcome of the spare carb would be. I am still suspicious of the one you have now.