Always appreciate useful feedback. The vent information is helpful although not in this case.
I got rid of the original plastic distributor many years ago and don't have filter screens in the aluminum replacement.
As I mentioned (maybe it was missed) there were 3 brand new caps out of the box that were DOA. No amount of humidity would account for that. Nor would the screens.
Brings me back to what I said in the first place. The internal traces are not being laid down properly prior to injection molding. You can see that referred to here in this page from Echlin ignition products.
http://www.napaechlin.com/media/2486...utor-Issue.pdf
They mention they use brass material which resists bending during the molding process. This is the problem with many new caps. Not corrosion.
Here is some really useful information if you have severe misfires and don't get a CEL. On other boards people have reported they had a misfire to cylinder 3. One guy found it accidentally when he pulled the 3 plug wire and his engine ran compared to with it on and it would not.
This is one of the problems areas which is occurring between the center post and adjacent #3 trace internal to the cap. Here's an inside look at a distributor cap showing the internal traces:
inside cap view
Don't give me grief about the white corrosion on this cap. I could have taken a picture of the new cap that failed but this used one was near by.
That boomerang trace next to the center contact is the #3 plug. It seems many fail right between the 2. Considering this type of failure wasn't a problem until a year ago, and I owned the truck for 20 years now. I would have to say the manufacturing process is suffering or as I said before, could be a dielectric strength issue with the plastic.
So if your Gen I Vortec is missfiring like a *****, pull the #3 plug wire off. If it then runs (better) or at all if it wasn't, the cap is surely bad. BUT be warned, I had this problem a year ago and the new cap out of the box had the same problem. I still have that new cap if
anyone wants to try it. There are other misfire conditions to these type caps but the #3 is no question.
Here are photos of the distributor vents:
top side dist
bottom side dist
These are for the people searching the internet for vent screens on a Vortec distributor.
EDIT one last item I researched the service bulletin .TSB # 03-06-04-041A
Here is the link:
http://www.oemautoparts.net/downloads/PB2.pdf
In it is not only the vents issue but I think more importantly an issue with oil vapors from a defective PCV system. Obviously this will be more of an issue with the OEM plastic distributor which suffers upper bushing wear.
Just FYI