Spark plugs

[Ed K.]

AC Delco plugs for a 64 327 come without the washer installed on the plug. The washer has a large diameter face with a small diameter on the opposite side. Does it matter which face is against the plug?

[John D.]

Re: Spark plugs

Ed, I often thought the same question for an eon . I don't think it makes a difference at all. I never saw anything in writing about it and I also have never seen a post here asking the same question. Now to wait for a better answer. John

[Ed K.]

Re: Spark plugs

I just sent an email to acdelco.com regarding my plug question. I was hoping to put the plugs in this AM but instead will wait for their response (NCRS responses are much quicker). I'll post their answer.

[Duke W.]

Re: Spark plugs

It's not a washer. It's a gasket - made out of copper - and designed to crush as the plug is tightened to the proper torque. It's made from two pieces that are crimped together leaving a crush space. It shouldn't matter which way they are installed, but I always installed them with the crimp facing the plug.

I haven't bought AC plugs in decades, but I recall that over-the-counter plugs always had a gasket in the box, and, of course, there were gaskets on the Flint-installed plugs.

Back when I had "plug fouling" problems and was always removing plugs for cleaning (which later turned out to be a sloppily assembled distributor all along) I bought a box of 100 of those gaskets.

Some racers installed the plugs without gaskets, which reduced combustion chamber volume slightly for more compression.

Don't expect much from "Delco". It's just a marketing organization, and I doubt if they have any job classifications that contain the word "engineer".

Duke

[Ed K.]

Re: Spark plugs

Thanks Duke. Yep, Delco suggested I contact an authorized AC Delco parts distributor, which turned out to be a local repair shop.

Their response was to install with the larger face towards the plug unless the mating head surface was rusted or damaged, thereby creating a bad sealing surface.

And............I should have referred to them as gaskets - oops!

[Bill M.]

Re: Spark plugs

Back when I had "plug fouling" problems and was always removing plugs for cleaning (which later turned out to be a sloppily assembled distributor all along) I bought a box of 100 of those gaskets.

Duke

The gas station I worked in had a plug cleaner and I cleaned a lot of plugs until I learned to run a hotter heat range. I always installed new gaskets. I still have a few gaskets left. I don't think I've seen these since the 60s! I believe that my first box had copper gaskets.