Odd door in ACDelco Gold Distributor Cap

[Mark E.]

I got this distributor cap from Summit because it was ACDelco Gold with brass terminals for $12.99. Turns out, the points adjustment door has a round screened "window" and the door itself does not slide open.

PN 19190541. See second photo in its parts listing:

https://parts.gmparts.com/product/acdelco-gold-ignition-distributor-cap-19190541

What's the purpose of this? There's no explanation in the parts description.

I can swap a normal door from and old cap so I'll keep it, but I've never seen this before.

[Jeffery C.]

Distributors generate heat during operation. Vented distributor caps help expel corrosive ozone gas that can build up due to electrical arcing inside the cap. Years ago, we used to drill holes in our drag cars Mallory distributor caps for that purpose.
That cap gives the appearance that it lifts from the bottom, and I think that is incorrect. It should slide up using the shelf at the top of the door; they are a little stiff to pull up.

[Owen L.]

Kinda funny, and sad, that the cap in their own promo pic is cracked in the lower corner of the door...

Screenshot 2025-07-08 at 4.36.29 PM.png

[Mark E.]

Distributors generate heat during operation. Vented distributor caps help expel corrosive ozone gas that can build up due to electrical arcing inside the cap. Years ago, we used to drill holes in our drag cars Mallory distributor caps for that purpose.
That cap gives the appearance that it lifts from the bottom, and I think that is incorrect. It should slide up using the shelf at the top of the door; they are a little stiff to pull up.

Thanks Jeffery. A cap for racing where there's little risk of moisture getting inside.

The bottom of the door has a tang protruding outward hooking the bottom of the cap that prevents it from sliding up. It looks like an intentional design but I don't understand it.

[Mark E.]

Kinda funny, and sad, that the cap in their own promo pic is cracked in the lower corner of the door...

Screenshot 2025-07-08 at 4.36.29 PM.png

Good catch Owen; I didn't see that. The cap itself appears high quality and it's made in USA.