I just purchased a 70 f100 with a 360 FE in it. I have been working on getting it running again. Right now my main issue is I’m not getting spark. I have already replaced most of the ignition components (coil, cap, rotor, points, condenser, spark plugs, and wires). I have a new starter solenoid and cables for battery.

Even after replacing all of these I can’t seem to get a spark form the coil. Coil tests good, it is receiving power from the battery but only around 5.6 volts at coil. My thoughts are my battery cables are bad, but other than that might not 100% sure.

Any help would be greatly appreciated.

 

There's a resistor wire that is in the circuit when it's running. Cranking voltage is full 12 volts. You can test if it'll run by putting a wire from the battery directly to the coil with a clip so you can shut it off.

 

Okay, I’ll have to try that. If that works I’m guessing that means possibly the resistor wire is bad it’s self?

 

The ignition switch bypasses the resistor while cranking so it might be a bad switch. If you do what I suggested it bypasses the switch.

 

Keep your old stuff just in case. You've just changed out at least two of the most problematic new parts that we have these days. Condensers and starter relay/solenoids!
It's always possible for one of them to give you trouble even brand new. So keep the old stuff handy just in case.

The resistor wire bypass is the Brown wire on the "I" terminal of the starter relay on the fender.
The START signal wire is the Red w/blue wire on the "S" terminal of the starter relay. You can disconnect the S wire so the starter does not crank and verify that you're still getting volts at the coil's positive wire without worrying about spinny-bits and your fingers and arms!
If you disconnect the positive wire from the ignition coil (Red w/green stripe) and then measure voltage with the key ON, what does it read now? Should be pretty close to battery voltage. If not, you should find out where the voltage drops.

And speaking of voltage drops... These old rigs have plenty by now. Keep track of how many volts your battery is reading directly whenever you are poking around at other wires, so you can see just how much is lost in various points. If your battery reads 12.4v for example and the power wire at the ignition switch under the dash reads only 11.1v then you have a bigger voltage drop than is desirable. When it comes to voltage, more is better. A little drop is expected and acceptable, but when you start seeing more than a 1/2volt drop, start looking at wires and connections and broken wires and rusty contacts.
In fact, speaking of rusty contacts, even though your ignition does not run through it, your old glass fuse panel is probably needing some cleaning. A good practice is to (with the battery negative disconnected) remove all the fuses (your '70 should only have 5 fuses I think) from the panel, clean them up, clean the contact points, then re-install them. This usually ends up helping a lot of things.
Unfortunately not the ignition, since it does not run through the fuse panel on our trucks. But with a little detective work you'll find out what's going on.

Based on your description, no.
If your starter can crank the engine (the starter uses more battery power than the next 10 power users combined) then it can certainly power the ignition.
Were you able to test the ignition coil power with the key in the START position? That reading is certainly low, and it 'could" be the resistor wire, but not necessarily. Lots of other things to check first on an old truck.

Since the coil does have some voltage (low, but should still spark) have you verified that the rotor is turning inside the distributor? If so, are the points opening up and closing completely each time a cam lobe comes up to the follower on the points?

Good luck.

Paul

 

You could be right, because I know there are lots of quirks to these old trucks. But I mentioned the other way in my last post just in case, because all of the Fords I've worked on had the bypass at the starter relay instead of directly from the ignition switch.
Wasn't there also an ignition switch change from one style to another (more reliable) just about this timeframe too? Or was it between other year models? I know it's been talked about many times here, but I never remember the specifics on when Ford went to the different type of switch.

Paul

 

How did you adjust the points when you installed them? The rubbing block on the points has to be on the highest point of the Dizzy's lobe. Set the points to .017. Or better off as close to 30 degrees of dwell as possible. Also put a dab of di-electric grease on the rubbing block. This will make the points last longer. Disc brake caliper slide grease can be substituted.
Did the truck run before you changed the points and especially the condenser? As noted above in the past few years there has been a ton of bad aftermarket condensers sold to us. It was so bad at one time I started joking about how many.