Scout II Ignition issues

Just for giggles, take another voltage reading at the coil + terminal with the key switched on just long enough to get the reading. No starter cranking. Just put the red probe on the coil + and ground the black probe to the engine block rather than the coil - terminal. Not sure if this is how you've done it previously. Let's see if there's still a significant drop at that location. The drops you're seeing in the cab aren't all that huge.
 
Battery was at 12.6 volts and the coil reading was 10.4 volts. And yeah I've been doing it that way no worries. I've got my whole weekend free and a friend who wants to help so I've got time to do whatever.
 
Okay, good to know. I'll have sporadic and limited computer access the rest of the weekend, but no matter. One more thing just to be sure I'm still on the right track with this. Can you test that wire with it disconnected from the coil? Sorry, I should have had you do this before. If you suddenly get a reading in the 12's, reconnect it and post up your results. If you get the same reading as before, my next suggestion is to trace it back as far as you can, even if you have to peel back layers of ancient electrical tape in the process. The pertronix needs full voltage at the coil in order to work properly, and its not getting it for some reason. There must be a faulty connection or some other issue within that length of wire somewhere. Losing 2 volts at the coil seems huge.
 
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Alright I just tested the voltage with that wire removed from coil. Same voltage as battery. Good call on testing that wire. Is the coil acting as a major resistor? It's one of the pertronix flamethrowers. Thanks again
 
Just read my service manual and it has bolded text saying that it's equipped with a resistor type coil and resistor. Where can I find this resistor?
 
Okay good. Glad I finally thought to have you test the wire in that manner. I should have thought of that much sooner. It would have saved you a lot of tail chasing and this thread wouldn't be nearly as long. Major duh moment for me. Sorry. I'm a far cry from mayben. Yes, ignition coils do have a internal resistance of varying amounts, depending on the unit. So what this means is you don't have a severe voltage drop somewhere between the battery and the coil. Your Scout being a '75 with the gold box ignition never did have the resistor wire as found on earlier models with breaker points. And you certainly do not need one now with the pertronix unit. So what I'd like you to do now is measure the resistance of your coil. First, disconnect all wires from both the + and - terminals, but remember where they all go. Then on your voltmeter, look for a selection on the dial face with an icon that resembles a pair of headphones or earmuffs. Switch the selector knob to the smallest number in that section. Then probe both your red to coil + and your black to coil -. The battery can be disconnected or connected for this. Either way it doesn't matter, as we're measuring ohms rather than voltage now. You should get a number something like 1.8. That's just an example, but it should be a low number.
 
Okay, great. Its a low-resistance coil and should work very well with your pertronix. So now were back to squares with the overriding question being, why won't this thing start? Its not a voltage or resistance issue. If you've got a strong spark and adequate supply of fresh fuel, the engine should run. I know you had it running right after you did the p-tron swap, and you haven't messed with the ignition timing since that point correct?
 
It doesn't matter that I'm still losing 2 volts at the coil? And I did time it because it sounded like crap and didn't perform well and I had it timed pretty well and it still ran afterwards.
 
You're not losing voltage to the coil, which is what I'd incorrectly thought was the case. The test you did with the wire disconnected confirms that there is full voltage present in that circuit. The loss you see is with the wire connected to the coil + terminal and is a due to the coil's internal resistance. Its normal.

Were you using a timing light when you made the timing adjustments? Do you recall what you set the timing to when you last had the engine running?
 
Okay, well that May or May not be a tad high for base timing in your case, but definitely not too high to prevent the thing from starting and running. Was the adjustment bolt tightened down afterwards to prevent the distributor from being bumped?
 
To be real honest with you I never could find that bolt. But I just checked it and tried retarding the timing and starting it but nothing.
 
You're going to need a bolt and lock ring in place to lock that distributor down once you have the timing adjustment optimized. Its too easy to inadvertently rotate the distributor when you're messing around on other stuff, changing belts and hoses. I'm not saying this happened, but t could have even been nudged by one of your helpers at some point while you weren't looking. Do you have any ether/starting fluid? If you do, give a decent blast down into the carb and hit the starter briefly. I'm back to thinking this is a fuel delivery issue. If this is the case, the engine should give some sign of life pretty quickly. If it doesn't, don't keep cranking and trying.
 
Oh well hold the phone dude! I thought that was something I had you check eons ago! We need to get on that one asap. Forget the starter fluid for now. Remove any plug you'd like to from the engine block. Reconnect the plug wire to the loose plug and ground the electrode to the engine block. Don't hold it with your bare hands. Have a helper hit the starter for a couple revolutions. See a spark or not?
 
Damn. Not what I wanted to hear. I'm remembering now that I did have you check for spark before you got the p-tron, but not since. This thread has gotten confusing. And with all the gaps in between activity it gets tough for my feeble mind to keep track of current status and progress.

So you installed the p-tron and the engine was running, then all of a sudden one time it wouldn't start. If I would have had you check for spark right then, we would have gotten to this point a long time ago. My apologies again for leading you on such a wild goose chase for nothing.

The lack of spark is your main issue. I have to ask and hope you'll be honest to the best of your ability. Was the key switch left in the "on" position without the engine running for any length of time after the last time you shut the engine off?
 
Come to think of it I believe that did happen once. Not sure if it was before or after the pertronix though. Don't tell me I burned the friggen thing out...
 
If it happened between the last time it ran and the first time it failed to start, its a possibility. Did you hang onto the original packaging by chance? It would be good to know if the one you have is a pertronix II or a pertronix iii.
 
Alright. Well let's not jump to the worst case conclusion just yet. The problem May be in the coil, which would certainly be less costly to replace. Try this. Disconnect the high tension wire that runs center to center between the coil and distributor at the distributor end leaving it connected to the coil. Ground the contact probe to metal and crank the starter to observe spark or not. Be very careful with this. If the coil is still good, we're talking about seriously high voltage here and would zap the hell out of you.
 
So just ground the end of the cable to the engine block and watch for spark whilst trying not to get fried right? I already had a run in with this cable and understand how much juice it has
 
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