Ignition problems, bad coil? or is there something else that could be up? (1 Viewer)

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Dec 7, 2013
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So, if I accidently messed up my timing (was having issues with idling and got a new carb and still had issues so next guess was timing) and now its not starting at all. Im dumb, I know, but its cool cause im learnin

So far I have
1. messed up the timing to the point I had to start over from ground zero
2. opened up my valve cover to check valve clearances (not hot, I know... and they were all over the place so thats a start)
3. ensured cylinder 1's rockers were "rocking" as the repair manual states. (valves closed)
4. installed distributor so that it points to cylinder 1 at 7 degrees BTDC
5. checked and gapped the points per the repair manual
6. sent it with the key and nothing happened beyond the starter motor spun

so now I am convinced I am not getting a spark so I got a test light (in line spark plug one and a light on a stick) but I was getting 4 volts on the center point of the distributor cap, and not picking up any voltage on the LT wire going into the distibutor body.

So I think my coil is shot. I found this on here and i seem to be getting 4 somethin ohm on the secondary circuit, it kinda drifts around as I stare at it more. The primary and coil seemed to be accurate based on this diagram.
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Got any ideas if this is my problem for not having any boom boom when I crank it? If I fire the parts cannon and get a new coil from the auto store are they plug and play? Or do I need a specialized one to jive with the resistor?
 
You can visually look for spark. Put a plug on a lead and ground the plug body on the head or neg bat terminal and crank it over.
If you can see a good spark , your timing might be off .[the timing can be badly wrong, but it will still spark]. No spark ? the coil could be shot or a wiring problem.
 
There's a few things it could be. If electrical anything always check fuses first. Also you could be off 180° on distributor so yea check spark when cranking and get sparkplug close to a ground ~5mm (engine block or something) if spark check fuel and carb. Just continue following etc... coil or follow electrical back
 
Seems you are checking all the right places. When they say you may be off 180*, rotate the flywheel until the you can see the timing mark. Once there check the valves (closed)and 1 piston should be at the top. If you don't see these conditions rotate the flywheel one full turn and check it again. I'm going off memory so double check your oem. Having the valve cover off helps a lot if you are in the learning mode or not.

Just remember the flywheel rotates twice to get one complete cycle of opening and closing of all the valves. The valve adjustment procedure will make this more clear.

Not sure if your 40 has points but if it does make sure you are not shorting them out to the casing( dist.). If they are super old just replace them and align them. Also ohm out you resistor. If working correctly you should have a voltage drop. See oem. The last thing I would suggest is clean all your terminals on this circuit. I use a small wire brush. Good luck. By the way, nice multi meter.
 
Seems you are checking all the right places. When they say you may be off 180*, rotate the flywheel until the you can see the timing mark. Once there check the valves (closed)and 1 piston should be at the top. If you don't see these conditions rotate the flywheel one full turn and check it again. I'm going off memory so double check your oem. Having the valve cover off helps a lot if you are in the learning mode or not.

Just remember the flywheel rotates twice to get one complete cycle of opening and closing of all the valves. The valve adjustment procedure will make this more clear.

Not sure if your 40 has points but if it does make sure you are not shorting them out to the casing( dist.). If they are super old just replace them and align them. Also ohm out you resistor. If working correctly you should have a voltage drop. See oem. The last thing I would suggest is clean all your terminals on this circuit. I use a small wire brush. Good luck. By the way, nice multi meter.
I found the multimeter at one of them reclaimed baggage shops in alabama, and I appreciate the guidance hopefully after some long head scratching and learning tonight I'll have some combustion happening
 
Assuming your static timing is correct, the dizzy is installed correctly- Check that you have power to (+) on the coil. Run a new wire from (-) on the coil to the distributor body. Make sure the insulator is intact where it attaches to its terminal on the distributor. Rule out a broken wire. Then go from there.
 
So, update. I ran continutity checks on all of my wires. All passed, I installed an inline spark plug light on #1 and cranked the ol girl over and got nothing. So I am not getting a spark. I checked the LT wire going into the distibutor and it has 12 volts on it. I figured Id see what my voltage was on the HT line and it was reading 2.7 volts so that would mean bad coil correct? I also checked the voltage going into the coil resistor. it also read 12v. I think its time to fire the parts cannon, and suggestions on a new coil? Not really sure what else I can poke with the ignition on to tell me why I have no spark
1671159288945.png
 
one thing to try is run a wire from bat+ terminal straight to coil+ and crank it over. When cranking only, these trucks bypass the resister and put full 12v to the coil+.
If there is a problem with this system it's possible that there is no voltage to coil+ only when cranking.

It could be the coil, but it seems strange for it to just die when you started adjusting the timing.
Long shot, but check inside the dizzy cap and make sure the little graphite button is in place and springs in and out freely.
 
one thing to try is run a wire from bat+ terminal straight to coil+ and crank it over. When cranking only, these trucks bypass the resister and put full 12v to the coil+.
If there is a problem with this system it's possible that there is no voltage to coil+ only when cranking.

It could be the coil, but it seems strange for it to just die when you started adjusting the timing.
Long shot, but check inside the dizzy cap and make sure the little graphite button is in place and springs in and out freely.
I checked the graphite button and it was getting 4 volts and it rebounded when pressed. I think I was having some spark problems prior to playing with the timing. The exhaust seemed to be pulsing when it was idling (choke closed, it would die with it open)
 
A continuity test is not always the best way to check if you have a connection. I would not call the coil bad just yet. If you have one strand of wire it will pass a continuity test but will obviouslyfail with a load. So if ohm it will best... or put a load you will have a huge voltage drop if you have one stand of wire or bad connection. I would double check with the coil on the bench or disconnected from the circuit, you have have 3 to 4 ohms between the positive and negative(primary). To check the secondary check between the negative and center tap, should 6 to 9 Kohms. The spark wires should be 25kohms. You can also check the casing of coil to the negative., Pos., and center. Should all be open. I would to know what read on the resistor.
 
Just confirming the rotor was pointed to #1 on the cap (firing order) and not the actual #1 cylinder when you installed the distributor? Rotor should’ve been close to #4 cylinder.
 
If there is no spark even after the hotwire from bat+ to coil+ and the coil neg to points wire is ok and the HT lead from the coil to dizzy is ok, it's probably a coil problem. [assuming it's just a points system and doesn't have an igniter]
Grime on the points is also possible. Gapping the points should be done with the dizzy lobe like this pic. [i'm sure you did it correctly, just covering all possibilities]

DISTRIB.jpg
 
Just confirming the rotor was pointed to #1 on the cap (firing order) and not the actual #1 cylinder when you installed the distributor? Rotor should’ve been close to #4 cylinder

So... I probably messed up the spark plug wires if I am reading this right. But Even if those wires were 100 percent wrong, I still should have gotten a light on my inline spark plug bulb thing. Which says to me I am not getting a spark. So to this message
A continuity test is not always the best way to check if you have a connection. I would not call the coil bad just yet. If you have one strand of wire it will pass a continuity test but will obviouslyfail with a load. So if ohm it will best... or put a load you will have a huge voltage drop if you have one stand of wire or bad connection. I would double check with the coil on the bench or disconnected from the circuit, you have have 3 to 4 ohms between the positive and negative(primary). To check the secondary check between the negative and center tap, should 6 to 9 Kohms. The spark wires should be 25kohms. You can also check the casing of coil to the negative., Pos., and center. Should all be open. I would to know what read on the resistor.
tomorrow morning I am going to just redo the 2 wires that would be suspect (we put in a new wiring harness a few years ago) I was having a hard time getting my multimeter to read anything when I shoved the probe into the center, which is why I put the spark wires in it when I tested. If that gives me bad data ill retry the meter reading in the morning.
 
If there is no spark even after the hotwire from bat+ to coil+ and the coil neg to points wire is ok and the HT lead from the coil to dizzy is ok, it's probably a coil problem. [assuming it's just a points system and doesn't have an igniter]
Grime on the points is also possible. Gapping the points should be done with the dizzy lobe like this pic. [i'm sure you did it correctly, just covering all possibilities]

View attachment 3194715
The contacts looked good to me, no grime (has not really been driven since we placed new points in a few years ago) and no pitting. I gapped it to .018 like the manual said. Pain in the ass getting that done with all them moving bits not wanting to stay put. I dont fully understand the LT line in the distibutor, but aint nothing a little google and pondering cant fix
 
If the truck started before you removed the distributor, and now it doesn’t, I would make sure the distributor was re-installed correctly before trying to chase other potential issues. At TDC on the compression stroke, the rotor should point towards the #4 cylinder, which is #1 on the cap for firing order.

Have you tried checking for spark with an actual spark plug? Lay it against metal while someone cranks the engine for you, unless you can do it remotely?
 
4. installed distributor so that it points to cylinder 1 at 7 degrees BTDC
This is confusing. Read posts by "deliverance"

In case you don't already have this I'll post it.
Valve Adjust.jpg
 
This is confusing. Read posts by "deliverance"

In case you don't already have this I'll post it.
10/10 have the plugs going to the wrong spots. Gonna fix that later today, but that still doesnt explain not having a spark. Once I can get a second set of hands tonight I will pull the spark plug out and visually test the plug vs having a light installed in the spark plug line
 

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