Need Spark Plug Cross please

[Guest bofusmosby]

I have a 1937 Pontiac 6 cylinder, and according to my book, the park plugs were AC K-7. I have not had any luck finding these anywhere, and was wondering if someone could look this number up, and cross it to a number that is easily avilable at most auto parts stores. The plugs that are in the car now are not the K-7's, so (in case the wrong ones were intalled by the previous owner) I just want to make sure that I put in the correct plugs. According to the service manual, these were 14 millimeter thread on the originals.

Thank you so much!

[lemondana]

I have an old 1942 Motor Manual and it calls for a AC-45. Then I have a old Champion book and the cross-reference appears to be a J-8 Champion. I'm not sure if these are available anymore, but I've seen them at swap meets quite often. The Champion book also states that these are 14mm, 3/8" reach plugs. Good luck!

[Guest bofusmosby]

I did a quick search on Ebay (for reference purposes) and I see that for example that there are a lot of different types of AC-45. There is 45L, 45XL, 45XLS, 45S, 45L, etc.. Will all of these fit, or do they have to be just AC #45?

Thank you!

[Larry Schramm]

Each one of the 45 spark plugs listed are different. Only the heat range is the same which is the 45. The 45xl has an extended length. 45xls has an extended length and a skirted - non threaded area below the end of the threads. The 45s has the threads with an area not threaded at the below the threaded area. And the differences continue.

Forgot to say the the 45 was the heat range. I think 44 was a hotter plug and a 46 a colder plug, but that might be backwards. Do not remember for sure.

Edited December 17, 2010 by Larry Schramm (see edit history)

[Guest Albert]

AC45's are a very common Plug, the champion J8's are used for briggs and straton lawn mower engines..

[Dave Henderson]

There was the plain "AC45" plug which was just that, AC45, with no suffix. The variations of it apparently came later. While AC would have been the car's original plug maker, (ironically standing for Arthur Champion), some consider Champions to be a better plug. On two pieces of original Champion literature I found the J11, set at .025, listed for your '37 Pontiac on a peep hole slip chart from the '50's. J8's were listed as the "old type" and J11's the "new type" on a 1965 Champion brochure showing their plugs for cars built from 1920 thru 1940. Hope this is helpful.

[Larry Schramm]

It was Albert C. Champion.

http://www.hemmings.com/hcc/stories/2006/01/01/hmn_feature21.html

Edited December 17, 2010 by Larry Schramm (see edit history)

[Guest bofusmosby]

Thanks guys, you have really been helpful. You have not only told me what I wanted, but needed to know too!