[60sstuff]

I know ..... just wanted to share what some may not be aware of. LOL.

The style of the AC spark plugs used from 64-70 +/- had the 4 green rings, plus a “Star” tip as shown below.

The large AC box (holding the 8 individual boxed plugs) only has “AC” on the boxes.
Later in the early 70s the square GM logo was inked next to the AC on the boxes.

When your looking for vintage AC plugs this information will quickly let you know roughly what years they were manufactured.

The price is typically higher on the early version dated sets.

This holds true on “all early parts” from the AC on their boxes.

Chris.

[rare4k]

Thanks, I learned something new today did not know about the tips

Sent from my moto z3 using Tapatalk

[unruhjonny]

huh - Cool!

I also didn't know about this.

Thanks for sharing!!

[Held for Ransom]

My white box set (R43) has a brass looking gasket.

[unruhjonny]

I will try posting this here, and if no reply here, before making another new thread;

Can anyone clarify for me the "commercial" versus regular plugs?

I found a set of C44S, that I bought over the weekend that as best as I can tell are a commercial version of the 44S;
The plugs shown in post #1 are vintage 44S plugs - so this IS related;

I am wondering if the commercial plugs just don't have the star shaped 'fire ring' tips - or something else to make them cheaper??

I did some searches, and found earlier printings of Delco catalogs that (as an example) show C43 plugs for 1968 Chev trucks w/327-2bbl motors, while the later catalogs have the same application as a regular 43 plug.

Thanks in advance for helping me!

[Jeff Hamlin]

It's my understanding that "Commercial" plugs are/were a hotter plug for use on vehicles that do a lot of stop and go driving i.e. commercial driving.

[unruhjonny]

so would that mean an in between heat range?

because in the case of C44S the 44 is the heat range...

??

[Jeff Hamlin]

I had an old AC book but be dammed if I can locate it.
Anyhow probably shouldn't have used the term Hotter.
IIRC it's the make up of the plug that resist on off heat better then the standard plugs,
but again don't hold me to that.

I'm going by memory and that's not so good to do anymore

[unruhjonny]

i have a 1993(?) issue, and I cannot find any further explination about "commercial" plugs;
it seems as though every other prefix, and suffix is explained, except this one.

[geeteeohguy]

The 'star' tip on the old AC plugs was advertised as the "Acinter Tip" back in the '60's. In the early '80's, at a shop I worked at, we had a huge supply of 20+ year old AC parts, including these plugs. I used them exclusively on my multiple GTO's at the time, including the old blue GF61 and red fuel filters. On my old tool box, I even had a decal showing the Acinter plug blasting off like a rocket. Neat stuff, as usual.

[unruhjonny]

I did some more digging;
I bought three Delco binders last year that I believe were owned by a zone manager.
Within 'AC Service Manual' SD-1000 I found a 1974 wholesalers catalog that had the followin chart:

According to this chart the 'Commercial' plug is actually in between heat ranges!
Interesting!

[dld]

What year were the three green rings with one wider green ring used .

I'm thinking that would be the correct plug style for 64 65 cars .

[NYGTO]

Does anyone have the AC part number for those plugs? Thanks

[60sstuff]

Gary,

Factory correct AC spark plug for 1965 is what I mentioned in my Original post.

Part number is 5612386 as shown below on all my dated boxes from 64-70.
They all have four green rings, same size and star tips.

Chris.

[NYGTO]

Chris, thank you for the info and additional picture. I needed to clarify.

[60sstuff]

I was looking through my 67 Pontiac Service Manual today and saw this illustration.

Same Same as above ^^^ four equal green rings and star tip.

[AllisonPontiac]

I had a neighbor in 1974 that was left her husband's 1965 Poniac G.T.O. , yellow car with white convertible top, tri-power, 38000 original miles on it. She used to take it out(cranking that wheel hard) and commented "I love it when I step on the gas, the front end lifts off the ground". She was in her 70's !