Had same problem. Check your red/green wire from the coil to the ignition switch. Mine had bad spots in the insulation in the harness and was shorting with the black wire form the solenoid on the fender apron.
If you want more info email me.
nelsons565@yahoo.com
Ted

 

Hey everyone, sorry I haven't replied lately... I appreciate the help and still have a problem with it. I got sick a couple weeks ago and didn't feel like working on it. I did mess with it one day, and my brother came over to see if he can figure anything out.


To answer a few questions: The carb hasn't been rebuilt since I've owned it, but I was thinking it will need to get done, if for nothing else, to have a nice clean, working carb. I did check wires in and out of the coil, and we found cracks in them, so I'll be running new ones probably this weekend and see if that helps. I will check the Ohms with my multi meter and make sure my plug wires are good, and at this point, may just replace them so I know they're new.

We did check compression, and all eight cylinders were around 105, which if I remember correctly is low, but it ran before I jumped a tooth so I don't see why this would suddenly be an issue. All the plugs looked good, though they needed re-gapped. We got it to run for nearly a minute, but with the timing advanced at around 10º, it was rough (vacuum advance disconnected and plugged) and it wouldn't stay running well until we upped it into the 20s. Anyway, that's where I'm at. I'll be trying suggestions and continuing to chip away at it until it runs again. I've been wanting to pull and rebuild the motor (turn into a 390), but have been putting it off, so maybe I'll have to look into doing that soon.


Thanks again!

 

Even if you do replace the plug wires, I'd "Ohm out" / check the new wires too, just for your piece of mind.

Other than that, sounds like you've got a good plan of attack! Good Luck and keep us all posted with your progress!

BarnieTrk

 

It's been a while, but I've managed to get a little more done lately. I replaced a few wires that were fraying and in poor shape, rebuilt the carburetor, and some other small maintenance items. I started testing things with my multi-meter so I can rule things out. My manual is old and vague, and searching for info this old doesn't help me at times. My coil has 12v with the key on, and the resistance measures within spec. I was still having a weak spark so I pulled my plug wires (they've been switched around so I didn't keep track of which was which). I'll post the sizes and the ohms below, but two were open loop, which could explain my misfire from a few months ago. I'll be picking up a new set of wires today and pulling all my plugs to clean and double check the gap.

32" wire - 3560 ohms
34" wire - 2120 ohms
34" wire - 2860 ohms
34" wire - 2100 ohms
34" wire - 1340 ohms
37" wire - 4410 ohms
37" wire - Open Loop
38" wire - Open Loop

The two open loop were from the same side of the engine. My book says to change if they exceed a certain resistance, but nothing on whether or not their too low. That one reading 1340 ohms seems pretty low but won't matter too much since I'm replacing the set anyway. If anyone has any more suggestions, I'm all ears!

 

This is the first time I have heard of measuring the resistance of the plug wires and I like it. To me there is no such thing as too low because less resistance equals more current which is a hotter spark. Resistance is needed on the primary power wire going to the points to keep them from burning out. I would be curious as to what the new wires ohm out at.

 

Well, I'm done. I can't keep screwing with this thing with no results. New plug wires, correct firing order, spark plugs cleaned and gapped to .034, new points and condenser with the points gapped at .017. Everything is getting the power it should. Carb is rebuilt and getting fuel. I had it running and driving a few months ago, but only for a day. Drove 30-40 miles that day with no issues. Sat for a couple days, drove it again, maybe 20 miles, and it wasn't running right. Since then I can't even get it to idle. It seems like a timing issue but even with it timed I get nothing. I am at my wit's end.

 

A lot of guys on this forum speak very poorly of "new" ignition condensers. Maybe try and find a new old stock original type. Several people here have had the same complaint as yours with random running even after replacing the points and condenser. They put the old original condenser back in and problem solved. Somewhere in another thread I asked about what the capacitance is of the condenser (it is actually a capacitor that you can buy from an electronics store) but I forget the answer. TA455HO Chad knows of this thread and is an electronics guy so mybe PM him if he does not come around.

 

600 volt 0.22uF poly film should work fine.

 

Bad vacuum advance diaphragm ???

 

Centrifugal advance freely moving? Is the distributor shaft gear tight or does it have free play? Was the new timing chain installed at the 0* mark or was it advanced/retarded 4*? This last one is a long shot but do you have the correct heat range on the spark plugs?

 

Everything in the distributor seems to move freely, and there seems to be no excessive play. When I replaced the timing set, I had to rotate it a few degrees so the points lined up, so I assume that's all good. One thing I have neglected to check, and I'm kind of kicking myself now, is the vacuum advance. Thanks Masked Rider for mentioning that. I took it of and immediately could see the diaphragm pieces falling out of the back. I blew through it and there was no resistance at all. A parts store in my area shows one in stock, so I might run over and pick it up. Not sure if it will solve the problem, but it needs replaced and can only help. Thanks again, guys! Without this forum I wouldn't be this close to having my truck back.

 

Hopefully your diaphragm prevents unwanted issues (bad joke I know). If this does not fix your problem I am concerned about your comment about rotating your dizzy a bit to accomodate the points dwell. Your problem could be there.

 

I'm getting ready to put it on now. I should have clarified, I had to rotate that crank a little to line the points back up on the timing gears after I jumped a tooth. Not the distributor. I reread that and that's was poorly written.

 

Ok, I got that vacuum advance on there and it ran more than it has recently; a whopping 3 seconds on its own. I need to get my timing light on it and see where I'm at for sure, but it's getting closer at lease.

 

Thinking about it after almost getting it running, I may pull the motor and replace gaskets and seals, because I have a clear exhaust leak. I have the ability to do it, so I might as well. My parking spot at work is pretty well defined by my oil slick, and I'd like one day to not be leaking as much (pretty sure front of the intake and rear main are the culprits). I suppose while I'm at it, I could tear the suspension out of my '85 Jag (parts car for my '73 Jaguar XJ6 build) and put it on my truck...