1952 B Spark Plug Recommendation

Hi there. Yep I have an orphan which I believe will be spending it's remaining days in my barn. Neighbor Ernie still owns it but I thought I would stick one of his #5 sickle bar mowers on it and use it this summer.

I did do site search and in Champions I saw the recommendation for D21 which is what I use on my Farmall Hs.

What do you recommmend in AC? I have had real good luck with AC C86s on one of my Farmall Hs. Thanks in advance.

My question was pertaining to the reommended spark plugs for the 1951 JD B using unleaded 87 octane. Besides the Champion D21s, what do you recommend in the AC and Autolite brands? Thank you in advance.

I have on my computer table two examples of this, a C85S and a C87 no Alpha suffix!
The primary difference is the number of the heat range #5 versus #7 and the S versus no suffix which is a very traditional sparkplug with no extended core nose insulator.

The present lineup of Delco AC 18mm plugs with a 1/2” reach are as follows:
C81, C82, C85, C86, C87 & C88 and altho I have made an extensive research into these plugs I may have missed some of the various numbers. One of the numbers I left out is the RC85S and the C83S as both of these have extended nose insulators and the R prefix indicates a Resistor sparkplug. The heat range numbers are C81 cold to C88 hot.

To find out more about Delco AC sparkplugs go to this address;
Link

Yours, M.L. Anderson