VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 Early Model H spark plugs

Does anybody know what was the correct, proper original equipment Spark Plugs used in the earliest Baby Grand and Royal Mail cars? We normally think of the big "AC Titan" plugs for the early 4 cylinders, but I wonder if there was anything in use before that?

I pulled the plugs out of my recently acquired early '14 Baby Grand last week, and found two "AC 1" plugs, which are dis-assemble-able. The other two plugs were (I assume) after market "Mosler Vesuvius 775" plugs. There are several Patent Dates on the Moslers, a new date about once per year, with the newest date being 1919. So I think we can conclude that all of thee plugs have been in the car since the early 1920's, which agrees with when it was supposedly put into storage.

You should be in contact with Ken Kaufmann. He wrote several articles on spark plugs that were published in the G&D. Don't know of anyone better authority than Ken.

I have an 1918 Ac advertisement that shows the AC plug which you have , a STANDARD AC , as being fitted to Chase trucks , Lexington , Howard , McFarlan , Wilcox trucks, and Locomobile.

The AC spark plug shown in the advertisement as regular equipment on Chevolet , and Chevrolet 490 (two separate listings) is the AC Titan , with the "Crossed AC" above the "Titan" It is a 7/8" long spark plug , where as the AC 1 shown is a regular length.
They are also a single electrode to one side , and not double like the plugs above.

Thanks, Gents!

Clearly, the AC-1 has a shorter "reach" into the combustion chamber than a Titan, below is a photo of it beside a Titan. The difference is about 1/4".

That is interesting what the application in the 1918 advertisement shows. So, we now know that the AC-1 was in production by 1918 - and the ad would also confirm that the Titan was in production by then. And not all Titans are labeled as Titans, some simply say AC. Second photo shows one of each.

I have sent an inquiry to Ken K a couple days ago, Chip. Hopefully he will have something specific that reaches back to 1913-14. The 1914 Parts Book simply says "spark plug." I guess my question is about the concern that the Titan was already in production that much earlier. We usually think of it as being the plug for more like 1920-26 time frame. Now we know it was available at least by 1918, thanks to Jack's ad. But that still leaves 5 years.

If your Standard AC 1 plug was a 7/8 long reach with the same size hex as the AC titan long reach , then it would have originally been designed for 1908 Buick , and was used up to 1914. After 1914 , Buick used the same AC titan as Chevrolet.
The AC Cico is also listed as regular equipment on Chevrolet 490's , and was replaced by the Ac Titan around 1920.

I believe that the AC with the cooling groove around the nut is a later plug than the other AC titan shown , but cant find any info on that plug .

Hi Don!

I'm surprised that Ray has not told you to call Chad Windham, he is member in eastern Oregon that has the largest collection of Spark Plugs. He might have the information which you looking for. I'm planning on sitting down with him at the Portland Swap meet and talking about plugs for the V8. I know that Ardie was planning on using AC Titan plugs for the V8. He had some documentation showing what was used in 1918. I can look to see what I can find in his stuff.

Bruce

Thanks to some PMs and emails from Jack39Rdstr, it appears the answer to the original question has come into focus. A Chart that was put up some time ago by Chipper, combined with some very early advertisements that Jack had, pretty well show that the correct plug for the earliest Model H would have been an earlier version of the AC Titan. I will almost certainly never find a set of 4 of these, but I will be looking!

Bruce, I think the later Model D V8 such as yours would have used the more commonly seen Titans as pictured above in some of the posts here.

Here's a 1914 advertisement for the earlier Titan, followed by the Chart I mentioned. I notice that the 1914 Model H lists a slightly different plug than the 1915-16 version. Many thanks to Jack for pursuing this with me.

(Note: don't be confused by the "1914 D" listed in the Chart. This is NOT a misprint nor talking about the later V8 - this is a car that only a very small handful were built (if any!) called the "Durant Special" - kind of stillborn and lost between the Little and the Model H - confusing).



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Hi Don,

I find this topic very interesting as I have never really understood the AC Titan Spark Plug. When you look at them, there are many different styles and are they all the same heat. How do you tell which is which? Any clue? And sorry if I'm railroading your topic since I'm kind of talking more about Model D's then H's.

So this picture shows what Ardie had installed in the V8 display engine. Notice that the ball end or tip, not sure what it really is called, is very long. You have some which are shorter. In my box if stuff I also have some which are short also. Anyone know what is really correct?



This next picture is of the boxes of the 8 AC Titan plugs which I think Ardie was planning to use in the car. Can you tell me what the 7/8" Regular means? or the 78RT means? Is this telling me that they are 7/8" long, in to the cylinder, and they are regular temp?



Now in the next picture is a sample of all the AC Titan's which Ardie had collected, I went through all of them and picked out one of every type or style. The left 3 are all 7/8" long or reach.



So what is the difference between all of these?

PS.....what does "Fancy Logo" mean Chip?

The only advertised terminal(nut) for Chevrolet's is the short ball nut. There is advertised a long terminal similar to the one shown on the display engine, but it has a flared out bottom adjacent to the spark plug is for a 4 cylinder Willy Knight. The one shown looks to be a new manufacture , perhaps by Ardie to keep the plug wires clear of the push rods.It may be unique to the D V8 but I don't know, what is shown in the workshop manual ? or on the V8 that was in the ford museum?. The spark lead end is the same as Chevrolet used on 4 cylinder 490's.

The AC spark plug on the left is a AC titan long, 78LT
2nd from left SAELT = SAE Long
3rd 78LT later version seen in 1925 advertisement
4th possibly MTCP Metric titan Carbon proof "possibly"
5th 78RT ( regular thread length)
6th SAET (regular length with reduced nut size "SAE" size)

The fancy logo on the spark plug list is the crossed over "AC" as seen on the AC1 spark plug seen above.

The only spark plugs listed in advertising for Chevrolet is the AC titan long 7/8 - 7/8 (ACTL 7/8- 7/8 in),and the AC cico (ACCL 7/8-7/8 in) for the earlier 490's
The CICO stands for Champion Ignition Company .

The Cico and versions of the Titan were the only types of spark plug produced by Champion Ignition company in 1915-1916 (at least)
There was also extra long , extra long body, and an in between
LONG and REGULAR , 78DT which looks similar to the regular , but just with slightly longer threads. Plus other specials for Ford Dodge etc etc,,

Heat ranges? most drivers and mechanics wouldn't have known back then and would have fitted the manufacturers recommendations only.( or what ever they had in the shop to sell to the customer and make a sale, as long as it screwed into the head and the car started,)

Jack has done an excellent job of summarizing and commenting on information in this thread and elsewhere.

FYI, There is several articles on early spark plugs published in the G&D. The articles I have copied start with an article by Chad Windham July 1993 and continue with several articles written by Ken Kaufmann and co-authored by Parker Little and Ken Kaufmann starting in late 1993 and extending through 1995. A careful review of those articles can help understand what spark plugs were factory installed and available as replacements for early Chevys.

I think a lot of the confusion or lack of understanding on the AC plugs comes from the fact that the early parts books and owners manuals does not give the part number for spark plugs. They do give you part numbers for spark wires and the terminal with the two prongs which connect to the ball nut. but no sparks plugs anywhere, even up to the 1924 combined parts book. I found this out when I got my 490 and started looking for the correct plugs, so started collecting the early Advertisements for AC when I found them. Even then a lot of the 1918 19 20 adds only show an AC plug and list Chevrolet, and the plug pictured in most AC plugs is the Titan Regular , not the titan long as needed. It took me a while to find the 1914 early AC plug add ,as I had it on my computer under "Champion 1914 spark plugs" so didn't come up when I was searching AC plugs.

Chevrolet didn't sell spark plugs or tires, tire valves, tubes through their part system. Guess they felt there were plenty of other places to get those items so why take up the space in the book or on the shelves.

Here is some information which I found in the stuff which I got from Ardie. Thought everyone might like to see it. One document show that the AC Titan Long was used for all Chevrolet's, not sure on the year.







Also what to say thank you to everyone, I think this has been very helpful.

Bruce, I can "Now" confirm that a Chevrolet 8 used a AC Titan Long 7/8 spark plug .

AC SPARK PLUG ADVERTISEMENT

The grooved Ac plug started in 1925 , but this one looks like a 1926 .

I just noted another AC 78S plug, this one is a "Sphinx". Are they common enough?

Regards
Al

Sphinx are made in England

Hi Jack,
Thanks, that figures !!

Regards
Al