Intermittent Spark Help

[wolk625]

Back again,

 

So last week, I was originally asking about a months-old overheating problem, only to find that my distributer was off-the-map in timing. After setting it somewhere in the neighborhood of correct, it ran great/cool, but raced in idle - traced it up and the idle adjustment screw was snapped off - extracted it and it idled great too. Drove it pretty much every day this last week with a mile wide grin.

 

But of course, maybe being dumb, yesterday I felt that it still wasn't tuned right - it was tough to start, stalled after letting off on a long straight. I had assumed that maybe the distributor had slipped back a little out of time, since that was the last thing I had adjusted. So I grabbed my timing light and went back at it - it was a little off, but not wildly out of time like before. After centering it to my line, it ran okay for about 2 minutes, then started to sound like a heavily cammed v8.. Wouldn't take throttle, and eventually would hardly stay running. 

 

In an attempt to diagnose, I turned on the timing light again and saw large gaps in time of no flash, then a few flashes, then no flash. I moved the pickup lead from wire to wire and saw the same thing. I then moved it to the two coil wires (signal and output), expecting to see very fast flashes, and again saw rapid flashing, no flash, intermittent flash, no flash, etc.      uuuuug......

 

Where do I need to start in my diagnosis to find this problem? Parts that are new - coil, dist cap, rotor, points, condenser, plug/coil wires, spark plugs. Other factors that may have played a part - this problem started happening right before an unexpected rain storm came through, and once I started getting soaked I pushed it back in the garage as fast as I could. I'm pretty confident that no water got in the engine bay, but I'm wondering if the air being soup may have played a factor. The distributor shaft I noticed has quite a bit of free play, but I would think that it would just drive to one side of the slop, and I'd be able to account for it in timing. Do I just buy a new one and cross my fingers, or will patience prevail?

 

Anyways, your favorite antique mopar millenial thanks you for all your help. Any suggestions are welcome.

[dpollo]

The distributor shaft play and worn cam lobes will cause a lot of grief and you will never get the timing correct

 

since even it you get it right for #1, all the rest will be off.  Try another distributor.

[Don Coatney]

First thing I would look at is this small flexible wire in the distributor. It is prone to shorting as it must flex every time the advance plate moves. This is a special wire and it is available. It was recently discussed on another thread so a forum search may tell you where to buy it.

 

[_shel_ny]

While in the distributor, make sure all the little screws that hold stuff are snug. Especially the condenser. Swap in a spare condenser?  Not sure if a condenser can be the cause of an intermittent problem, or if they just fail completely. Don't drop the little screw that holds the condenser. I dropped one down in while out on the road in the late 60's/early 70's. Good thing I had company along that was smart enough to pull a dizzy to dump the screw out, and get it back in the correct place.

[dpollo]

Looks to me like there is interference between the strap-like condenser lead and the flexible lead.

I prefer condensers with wire leads.  Note to Don, I just passed a line of cars when my car quit. After trying to look cool I raised the hood and found the little screw which holds the points spring had backed out.  I promptly dropped it in the gravel under the car.

Good thing I was a whiz at "Hidden in plain sight" at school.( my only A+ subject)   I lay under the car until I spotted it. Put it back with the aid of an antifreeze tag tie wire and we were on our way.  Thank heavens this was back in the day when 50 Plymouths were plentiful enough that I remained anonymous.

[vintage6t]

I'd be suspicious of a bad condenser. But whatever the cause, once you do find the problem and correct it check your point contacts to make sure they are on burnt. Also check to make sure your plugs are not fouled as a result of poor spark.

[wolk625]

There were some bare chunks on the flexible leads down in there. I took a donation from a similar sized speaker wire and dropped those in. It's firing pretty consistently at idle but under load I'm getting a lot of popping. Probably carb stuff? I'll play with it more after the holiday weekend

[greg g]

Are yourspark plug leads correct for proper firing order? I have repaired the internal wire using rubber cement and thread. Swab the deteriorated area with glue, wrap the thread around and then recover with more glue. You may also want to check the insulation block where the coil wire passes through the distributer body. Also make up a jumper wire with some alligator clips on the ends. You can use it to power the coil directly from the battery. The clips allow a quick disconnect to shut the engine off. Using that (after you remove the ignition lead from the coil) will bypass your ignition switch which, if the engine runs better, will tell you the fault would be between the battery and coil through the ignition wiring circuit.

[halffast52]

if it idles fine and backfires or pops under load I would bet the condenser is bad

[Don Coatney]

Have you checked the accelerator pump in your carburetor?

[wolk625]

Finally got a chance to put hands on the car again today, I decided to try just swapping out the condenser with the original one I pulled out, and sure enough, all of my issues went away... So my new condenser I bought was junk. It was this "BWD" brand, only thing anyone around here had in stock. Out of curiosity, is there another easy to obtain brand of condenser that anyone can vouch for?

[Plymouthy Adams]

outside of testing the condenser for the proper microfarad rating...not really...

[Dartgame]

I had a similar issue after I got the 52 running. I had it idling in the garage showing a buddy how nice it ran, and then the engine just stopped running. Kind of embrassing.... I checked for spark and was getting some, but not consistent. Turned out the new condenser which had only 1 hour running time was bad. Pain in the butt because when swapping the condenser - at least on my car - the point adjustment goes out and you have to reset it. Once changed out all was well again. I have another dizzy which I am going to convert to pertronix and keep the point dist. as a back up....

Damn cheap parts these days....found an NOS condenser/points from a specialty parts vendor, which I will use if it comes down to it....