Distributor leaking spark from rubber(?)

[m-mman]

The car is a 1929 Cadillac, everything is rebuilt and new but it wont go over 40-45 mph. It is as if it hits a governor. No stalling, just loss of being able to do anything more. 

I expect a long troubleshooting process, thankfully I am getting expert help and advice from Ed Minnie.

 

It has a Classic & Exotic new distributor that Ed put on his machine and verified as functioning well. I reinstalled the distributor and while adjusting the timing and what not, I touch the cap and it bites me(!) It is leaking electricity from somewhere.  Since a loss of spark or cross fire could cause the symptoms I decide check it out where the electricity is coming from. 

 

I use a test light probe and connect a wire to a good ground such that I can touch and probe around the cap and look for any sparks with the lights out. Turns out there are plenty. All coming from the towers on the cap. Most are very small and seen only with the lights completely out, but they are there. 

 

I remove the cap and wash it in a degreaser soap and a brush just in case there is any dirt or carbon tracking. No cracks are seen on the cap. But it is an 'old original' cap. . . .

 

The wires are Packard 440 solid wire core, all new 6 months ago. The ends are soldered to the plug and distributor connectors. 

The rubber nipples are Steele Rubber from about a year ago.  All wires are shoved tightly into the cap. 

 

I continue getting sparking to ground so I wrap each plug wire in electrical tape and pack it back in under the rubber nipple. 

This stops MOST of the stray spark leakage, but it continues on one wire especially. (pic attached) It is bright and hot. As you can see it seems to be coming from either the rubber nipple or the plug wire. 

 

Strangely I am also getting a VERY SMALL spark from the clip that holds the cap(!)  It is very small and not photograph-able. As I understand things, there should be no electricity getting to this part. It is only one clip and I cannot see and cannot provoke any sparking from the distributor body itself. 

 

The only thing that is not new is the cap itself but the sparks are not seen when I touch anywhere on the cap itself, only where the wires enter the towers. (and the clip) 

FYI - I called Autozone and I guess they just cant get a new cap for a 90 year old car, so I will have to reuse it . . . . 

However if the cap is somehow leaking can it be 're-sealed' by spraying on a clear paint or nail polish? 

 

Any ideas? I am stumped. 

The car runs fine in the garage. I haven't tried it back on the road yet. Maybe this isnt really much of a problem operationally? 

 

To solve the main operational issue, Ed says he will next walk me through the carb and fuel system, but this is something. 

[edinmass]

Close the gap down on the plugs to half of what they call for and take it for a spin. Also too much fuel......running rich significantly increases the secondary KV’s. I would also replace all the wires as that is a very inexpensive elimination of a problem.  I’ll be on an airplane after 1 o’clock but you can call me anytime this morning. Ed

[TerryB]

Your cap and wire look wet, is it?  That will create leakage.  I’m thinking your old cap is porous and not insulating as it should.   In the parts for sale section there has been an ad for an ignition parts seller.  You might want to contact them for a new cap.  High voltage takes the path of least resistance and it seems your cap has low resistance.

[Old buicks 2]

Contact for NOS ignition parts is   Tom VanMeeteren   402-359-5762  from his ad in "parts for sale"

[Rusty_OToole]

The only time I have seen that, is when there is too much resistance in the plug wire or plug.  You say you have good solid core wires not resistance, so that leaves the plugs. Are they resistance plugs? Can you get the old fashioned non resistance? And as Ed says, don't gap them too wide.

[Guest]

The inside of the boots could be dirty allowing the current to short out.  I find the life of wires is at least twice the life of boots.

[edinmass]

I had this distributor on my distributor tester last week. It’s definitely a secondary problem, and possibly fuel also. One step at a time. I would install all new wires, boots, and plugs. Keep the gap tight, and take it for a spin and check for issues if high KV’s. Then you can address carburetor and fuel issues. 

Edited March 30, 2019 by edinmass (see edit history)

[TerryB]

Maybe something strange with how the block is grounded to the rest of the electrical system?

[m-mman]

Ok, I got to go to the garage for a few moments. 

The non-resistor plugs were gaped at .025. (book says .025 - .028) I reduced them to .020.

Wires are all new.  Rubber is soft, no cuts or cracks can be seen. (again wire core, no resistance) 

 

The boots are one year old from Steele Rubber. Again no cuts or cracks can be seen. 

I put a wrap or two of electrical tape around each boot. 

 

Running it in the garage and no more stray sparks are seen.  🙂 

However I still can elicit a big spark from the #1 wire on the cap. (the one in the picture) The others elicit no more sparks. 

Strangely I can still get some small sparks from the CLIPS that hold the cap(!)  Since these are 'grounded' at the distributor body, and they are not touching the ignition anywhere, I am wondering if this could be some static electricity????

 

Touching the probe to each plug connection and I get a good spark there (as you would expect) so each wire must be conducting well. . . ?

I can also elicit a small spark near the coil tower & boot. (smaller than the #1 at the distributor) but these do not stall or stumble the engine. 

 

Have not had chance to test drive. Leaving soon for family weekend event. 

 

I full understand that this strange situation is going to take time and Ed, I appreciate that you are staying with it and supporting me.

We will just keep digging slowly and methodically.

Its a hobby, this is the fun part correct? The only dead line is when you get out here to see it for yourself in June. 

Perhaps it can even develop into diagnosing something that you have never seen before?  Unlikely. 

Jim

[TerryB]

Change plug 1 with another plug and see if the spark issue stays with plug 1 wiring or follows the plug.

[tom_in_nh]

I suspect that your rotor is grounding out, thus creating a path for the secondary current to flow where it should not. 

Edited March 31, 2019 by tom_in_nh
Spelling error found (see edit history)

[edinmass]

You need to ohm out all the wires using a dvom and not a cheap one. You can also test for high KV’s using a scope. I still recommend changing all the wires, plugs, and clips. Too many weird issues today with modern substitutes in the ignition system. A bad rotor is a possibility, doesn’t make sense why number one offends more than the others. Retarding the timing using the starting control should drop the KV’s while running if you have an oscilloscope. It’s going to be something simple, but hard to see.