Small crack in a D308

[Jeff A.]

I was going through some caps - came across this Patent Pending cap with a small crack - it looks like it had been arching.

Can this old cap be salvaged, or is it trash? I just hate to throw these away.

[Dick W.]

Re: Small crack in a D308

It are trash

[Joe L.]

Re: Small crack in a D308

I was going through some caps - came across this Patent Pending cap with a small crack - it looks like it had been arching.

Can this old cap be salvaged, or is it trash? I just hate to throw these away.

Jeff------


You can keep it for configuration REFERENCE but not as a usable part.

[Jeff A.]

Re: Small crack in a D308

I figured as much - just hate to throw anything away.

Pulled that off an untouched junk car in a farmers field, Hate to think that was why they parked it all those years ago?

[Michael M.]

Re: Small crack in a D308

I hate to disagree but I have restored hundreds of D-308's. As long as the contacts inside the cap are in good condition the outside is just a cosmetic repair. Many things can be done to improve the outside appearance of the cap. I worked with AC - Delco years ago on this subject. They supplied me with the blueprints of the cap, "L" shaped lock screws with springs, doors for point access, and the center contact inside the cap for the coil wire. After the repair you must put the D-308 on a Sun distributor machine to test the cap. Most important the D-308's should just be used for judging not a every day cap these days.

[Paul J.]

Re: Small crack in a D308

I hate to disagree but I have restored hundreds of D-308's. As long as the contacts inside the cap are in good condition the outside is just a cosmetic repair. Many things can be done to improve the outside appearance of the cap. I worked with AC - Delco years ago on this subject. They supplied me with the blueprints of the cap, "L" shaped lock screws with springs, doors for point access, and the center contact inside the cap for the coil wire. After the repair you must put the D-308 on a Sun distributor machine to test the cap. Most important the D-308's should just be used for judging not a every day cap these days.

Michael, he said it was cracked. In my experience that means it's trash. How do you repair a crack to last more than a few minutes of operation?

Paul

[Jeff A.]

Re: Small crack in a D308

This is another cap I have.
Weird thing is - I seem to find a lot like these.
The center contact is melted away.
Most of these caps come off cars that look like they were running at the point of being junked - completely intact in every way.
Any way to save these?

[Dan D.]

Re: Small crack in a D308

I was going through some caps - came across this Patent Pending cap with a small crack - it looks like it had been arching.

Can this old cap be salvaged, or is it trash? I just hate to throw these away.

That is not just a crack, part of it is burned away. What happened is it arced and carbon tracked. The carbon track is a conductive path between the 2 terminals. Whatever you do to try and dig out the carbon, the dielectric will still be to low and it will probably cross fire if you try to use it. -Dan-

[Michael M.]

Re: Small crack in a D308

Jeff I have the center contact carbon balls from Delco. But to answer Paul's question, it's hard to comment on a picture. I would have to see the cap to examine the extent of the crack. To me the picture posted looks like just a piece of the cap is missing. Would be good to have a picture of the same area but from the inside of the cap.

[Jeff A.]

Re: Small crack in a D308

Can't see the crack from the inside - but it was arching, as you can see the burn trails. so I would bet the crack goes all the way through.

Is it possible to replace the melted center balls? I have a bunch with bad center balls.

[Jack H.]

Re: Small crack in a D308

The housing material is Bakelite. That's a form of compressed wood pulp (NOT a traditional plastic). You need wood working skills to properly restore an aged/damaged part...

Go Google the subject and you'll find this is a speciality area that's embraced by those trying to save rare antique radios & electronic items from the pre-50's era. In the hands of the right guy, 'miracles' can happen!

But, then we get down to the cost/benefit economics and methinks you'll want to pass on attempting restoration 'heroics' with this commonly available rather 'cheap' item...

[Michael M.]

Re: Small crack in a D308

Jeff, the deal is to find the carbon balls from a supplier. About 18 years ago Delco sent me 50 carbon balls, doors, and "L" shaped lock screws with springs. After using the first 50 I called again and they sent me 25 more but said that this is the last time they could send me these items. The balls are pressed in the center for the coil contact. I used a metallic epoxy on the sides for more insurance.