JD D Spark Plug Number

[Bobl1958]

Can someone tell me that correct spark plug for a 1936 D. The one I have has very old plugs in it and I would like to change them out. Hoping for AC or Autolite plugs if they make them. Thanks - Bob

 

[JD Wayne]

So I looked up the part number, from John Deere it is AD2860R. It will cost you about 5.25 each from john deere and it is an AC Delco Spark plug. Also you can look for AC600R, which effectively replaced the original AC77L which was originally produced at the time of the tractor. If you want a Champion spark plug the part number will be Champion W-18. Here is a nifty link for a cross reference to spark plugs. http://wfmachines.com/discus/messages/96042/Spark_Plug_Cross_Reference_Chart-217247.pdf.

Hope this helps!

 

[Bobl1958]

That does Wayne. Thanks a lot - BOb

 

[gtx1967jewison]

If you have very old plugs they are take-apart ones & can be serviced. They are very scarce & worth a lot.

 

[Lee B]

W-18 is a 7/8 x 18 tpi plug where the hole calls for an 18 mm thread such as the D-21 champion which I use and recommend. Sometimes these one off cross reference charts have wrong info in them. W-18 belongs in a model A ford.

 

[Mike M]

IIRC the old fords and real early Deeres used a plug with 1/2" NPT.

 

[buickanddeere]

The Autolite 3095 or Motorcraft F11 are possibilities if it's a 1/2 pipe thread.

 

[Mike M]

I don't remember where the cut off is but I'm pretty sure his is too "new" for the 1/2" NPT ones.

 

[Lee B]

109,944 is the serial break between 508 R plug and a whole herd of turtles ever since then that include AC77L which I take to be 18mm.

I did read about Ford going his own way with 1/2 NPT on the model T, but the model A came along a bit after. What I didn't know was that the AC in AC Delco stands for Albert Champion and yes, THAT same champion. He was hired often it appears, all his former employers kept on keeping on without him, but they kept the name in one form or another. He must have had a knack close to a trade secret to have a name so sought after in that particular field. Even ford it appears after a little more searching on 508 R plug crosses to a modern champion 525 and it IS 1/2 NPT just like this one.


<img src="http://photos.yesterdaystractors.com/gallery/uptest/a190379.jpg"

 

[toot]

Autolite 3076

 

[Lee B]

My bad there - AC77L is 7/8 x 18 tpi so the D-21 at 18mm I offered wouldn't even fit. And the W-18 is a proper call after all. News to me that different sizes of spark plug holes were so varied. The A breaks at serial number 488,000 from the 7/8 size to the 18mm size. From what I can gather the D never makes it into the 'modern' age with a similar break.