Problems with an aluminum Vortec distributor

[speedygonzales]

Summary for those that don't want to read: Was going through distributor caps and rotors so fast, I had to bring spares on long trips. No joke, I had to replace them on a return trip from Jersey to Virginia at a state rest stop. I think this will correct that problem.

I think the inside corrosion was creating an environment that for lack of a better term, "bred" more corrosion.

So you know the drill, the OEM plastic distributor cracks at the cap mounting holes.
You decide to replace it with a nice aluminum aftermarket unit like the one from Summit.
https://www.summitracing.com/parts/sum-850098

All is good and life goes on. For a few years. Then you start eating caps and rotors like Hitler through Poland. I mean real bad. Here's a picture of the cap I took off yesterday with less than 400 miles on it. Incidentally for more than 10 years, I never had this issue with the OEM plastic POS.

https://s1371.photobucket.com/user/S...sfnzx.jpg.html
NOTE: Seems that no one offers caps with brass contacts any more.

Here's the inside with cap and rotor gone.

https://s1371.photobucket.com/user/S...spgic.jpg.html

Here is what I think is causing the issues. The corrosion on the top surface inside the cap.

https://s1371.photobucket.com/user/S...8y6oh.jpg.html

I removed the optical pickup and cleaned the inside surface and painted it. Then baked it on. My hope was to seal out the corrosion and prevent premature wear to the cap in the future. Time will tell if it works.

Incidentally, the 2 vents in the bottom, which for some reason were made to turn right angles were clogged solid with corrosion as well. I drilled straight down so the holes were straight and cleaned out the ones at a right angle so it will breath better.

My suggestion for those that live in a humid environment and buy one of these aluminum distributors, pull it apart and paint it before you install it.

[special-K]

Thanks for this info. It is surely helpful. I haven't had a Vortec truck as of yet.

I wonder if the black cap material has gotten better over the years. Way back when I learned black distributor caps were crap. The tan, blue, or red caps were of better quality bakelite. It's been decades of changes, but still I wonder.

My truck died on me one rainy night. A friend came and towed me in. He saw my black cap, took it off, showed me the carbon tracks, and tossed it in the can. I told him I just put that on there*. From that same can he pulled a dirty old tan cap he removed from a customer's car he did a tune-up on. He said you'll be better off with this old thing. He was right, carbon track problems solved. I went with Blue Streak ignition parts, or at least upgrade cap, from then on.

* I had been having no start issues when it rained or 4wheeling with any water/puddles involved. Lectramotive found a home in my glovebox

[speedygonzales]

Interesting point about the plastic cap material. As I posted before, I've had for lack of a better term "side firing" issues where internal shorts have caused missfires. Most likely due to either air bubbles during the molding process or using a low dielectric material.

That is an entirely different problem than the one I'm showing here. Here i have pictures of an extreme white corrosion on all of the cap terminals in just 400 miles.

I surmised it was due to the interior surface of the aluminum distributor having the same corrosion on it. I believe it's breeding more corrosion. However, I also noted the vent holes were clogged and not made correctly.

So I fixed the vent hole configuration AND painted the interior surface. Time will tell if it is going to help.

Incidentally, the good quality caps are getting harder to find.

Here is an article in on all cylinders about aluminum terminal corrosion.

https://www.onallcylinders.com/2016/...ou-avoid-them/

There are still a few good caps listed on Summit's website I may try that still have brass terminals.

[Mr_Rich]

If you come across a dist cap with brass terminals non-Vortec pre-95 and not made in China please let us know. I used to rely on Accel dist caps until they were made in China. I had fitment probs and gave up on them after that.

[speedygonzales]

Originally Posted by Mr_Rich

If you come across a dist cap with brass terminals non-Vortec pre-95 and not made in China please let us know. I used to rely on Accel dist caps until they were made in China. I had fitment probs and gave up on them after that.

That wasn't even a tough one......
Not knowing which version you need, I included all 3

http://www.taylorvertex.com/product-...=219916&sID=75

http://www.taylorvertex.com/product-...=219917&sID=75

http://www.taylorvertex.com/product-...=219921&sID=75

All made in the US and use brass contacts

All low priced at Summit

[special-K]

I bet you are right about the corrosion spreading/breeding. And the clogged vent seems the likely culprit. Small area and just a small vent, but it's needed or it wouldn't be there and that's all the passage it needs. Clog that up and you found out why they are vented. I bet this isn't an issue, or as much of one, in arid areas. Shoot, last year were we all in a damp environment jn the Eastern States. It's only gotten sorta dry once or twice since.

I am sure a low quality cap in this situation would serve to help the moisture problem along

[junksaver]

Here is the cap I put on my 99 tahoe last summer. It has brass terminals and is vented. I also have an aluminum distributor that is 3 years old. The cap has about 10k miles on it now and is doing fine. I think I bought it from rock auto.