short in distributor keeps reappearing - any ideas?

[Tom Wesenberg]

Two important things to look for in the distributor are the insulating washer that goes under the condenser screw head, and the bottom plate wire terminal. The insulating washer not only keeps the buss bar on the lower plate from hitting the cast body, it keeps the screw from bottoming out in the end of the condenser, which can lead to the condenser terminal spinning and ruining a good condenser. The flag terminal MUST be bent at 90* (as Marco has pictured in the past) so it hugs the hex nut on the points pivot stud. If it isn't bent down at 90*, it can reach the spring and short out.

I better add one more thing to check is that the points spring and thin copper strap must not touch the distributor cam at any time, or it causes problems.

Just to be sure, when you check for voltage at the points, you DO HAVE THEM OPEN, don't you? If the points are closed, then you are sending the ground path to the coil, and will have no voltage reading.

[dumb person]

Not sure if anyone mentioned this already but the lower plate in mine has a metal thing riveted to it that the condenser is screwed to and the armor cable makes contact with. Mine appears to have decaying insulation where the rivets are. Could be worth checking if you think it is shorting there.

[30ccpickup]

Over painting the distributor body or the head can prevent proper grounding.

[SDJason]

Another update -
I remembered that I had my old condenser (with a broken off tab) still laying around; I figured duct-taping the tab on would be enough to have a connection to test things out.

Success - sort of. I successfully got voltage back to the points arm (yes Tom, I made sure to keep the points open with a piece of paper when checking - I have forgotten to do that before in the past, though, so thanks for the reminder).

But - still no go on starting the engine. So, I tried pulling the coil wire and holding it near a stud on the engine block and manually pushed in the starter button - yes, there's spark.

I guess maybe I should have loosened a brass strip and actually witness spark going to a spark plug; I'll try that tomorrow, it's getting kinda late & my brain's frazzled (and a bit frustrated).

At least I know that the "new" condenser (that had less than 200 miles on it) is probably bad. Maybe the duct-taped old condenser is good enough to generate spark, but not good enough to get the engine started? I guess I'll find out once I buy another condenser - thanks Joe K for the NAPA tip - there's plenty of them around; I'll try calling them and see if I can get one in short order.

Thanks for all the tips - I feel like I've been going over the innards of my distributor with a fine-toothed comb over and over again now...it was kinda fun at first, but now is just a bit frustrating...

[Tom Wesenberg]

You can solder the ground strap to the condenser body.

If you've never experienced it before, a shorted rotor can leave you scratching your head for a while. The first time I saw this was in the 70's when I was tuning up a customer's newer Ford. The coil had good spark, but then engine wouldn't fire at all. I finally traced it to a rotor sending the spark from the flex contact, through the plastic, and to the steel shaft.

[Fred K-OR]

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Another thing to check may be your points-are they in good shape?

Just a thought again.

[mleder]

Would you happen to have a different lower plate that you can swap out for a test run?. When the plate goes bad the tab on the bottom will show continuity to the main part of the plate. The insulating washers that the rivits pass thru may be old or on the intermitant part of being good/bad.When pressure from the ingnition cable or even reassembly into the distributor body or vibration from engine running might possibily cause the the plate to go to ground. This condition may only happen possibly when you've gotten everything togather. This could disapear when you remove part of the assembly or move it to the bench for inspection and testing. You would not be able to determine by a visual check of the rivits or washers if this odd thing were happening. A long shot but one more thing to consider.

[jmeckel]

All kinds of ideas listed so far, and all good ones to!. So to add some "out of the normal" problems I have seen on coil type ing. issues. One thing to try, is watch the coil, and dist in the dark, you maybe surprised to see sparks at places you never thought. I have found both coil and dist cover problems this way. The smallest carbon path in the wrong place can cause all kinds of problems. I posted it before but now I found a picture to add, take a good look at the copper strap on the points, I am here to tell you I spent hours working on a dist "shorting out" problem, no matter what I did it would start to work and then fail, it was all caused by the point strap that would touch the case whenever it felt like for just as long as it felt like. It about drove me crazy (maybe a short trip to crazy anyway!).

Model a points.jpg

[P.S.]

Originally Posted by 1931 flamingo

The NAPA condenser in post #16 says 36 month/36,000 mile guarantee. FWIW
Paul in CT

Here's the link to the Napa condenser.

Was really surprised to see all the Model A parts that Napa has, especially the original style Champion spark plugs for less than the Model A houses sell them! Here's the link.

Some other distributor parts from Napa:

Points
Rotor
Oil pan gaskets
Head gasket
Intake/exhaust manifold gasket
Full engine gasket set
6 volt ignition coil
Ignition coil mounting bracket
Fan belt
King pins
Generator brushes
The list goes on....

[Joe K]

There's still some Model A stuff out there in the real world.

Too bad not Midas Muffler. I have one of those on my truck still.

Do you think the warranty is still in effect?

https://www.youtube.com/watch?v=mFOWdIPQImk

I loved the commercial. Trouble is I find as the years pass I more and more resemble John Hoyt. Well, maybe Jack Benny.

Joe K

[[email protected]]

I am thinking that I have a short also and appreciate any help. I am not a mechanic as you can tell.

1. About 3 yrs ago, replaced all parts inside distributor, coil, points, lower and upper plate with new black wire, all new wiring harness, stem to crank. Car ran nicely for short period of time.

2. In that same timeframe when we had it running, I tried to start it and would not start. Traced it to no spark. Changed coil again. Still no spark.

3. Traced lack of lack of connectivity to a 90 yr old ignition switch. Replaced it last week with new one from MacÂ’s.

4. Replaced old style (lower unit) condenser with new.

5. Car started for only 3-5 seconds - ran rough so I tried to advance points manually on column and engine quit. This has happened 2 times in about 30 attempts to start. Again no spark. Seems like it might initially have spark and then it goes away (why I think a short).

6. Noticed that Mac’s sells point terminal mounting kit with insulating washer so I ordered that. Also noticed in thread that condenser screw should have insulated washer. My condenser has 2 screws, one to hold it in place and other screws to ground lower plate. Which one gets the insulated washer?

7. Any other advice would be great.

God Bless

[Jim Brierley]

The dist. plate needs a good ground. I've had such a problem and moving the advance/retard lever while driving was a temporary solution.