Farmall MD spark plug size

SW EM · Nov 30, 2016

I was looking on this site for a set of new plugs for my MD and I remember being told to get the ones with the extended tip. It seems that there are 2 sizes to choose from...does anyone know off the top of their head which one I should choose?

14mm thread, 3/4 in reach
14mm thread, 3/8 in reach

I'm not at home with the tractor now otherwise I would remove one and match it. Thanks in advance!

Janicholson · Nov 30, 2016

The reach of the plug is more like an inch and a half. It is totally specific to that engine group and expensive. It will not run or run so poorly that makes no difference with conventional plugs in it. Sorry, but the electrodes need to be way inside the decompression chamber. Jim

SW EM · Nov 30, 2016

I did some more searching online and found that Champion D89D sparks plugs are the ones I should get.
This MD hasn't ran since we've had it. It does have plugs in it already, but I haven't paid attention to them. I was going to spend some time with it and see if it would start and run on gas first. I will need spark plug wires for sure, those were missing. It has a H4 magneto too, I'll have to see if it puts out a spark or if I will have to clean it up too.

Janicholson · Nov 30, 2016

There are some crossover part numbers for other brands. Steiners and other houses have the plugs, but expect wallet depletion. jim

John M · Nov 30, 2016

Keep in mind that magneto turns backwards from the normal H4. Heres a crossover chart for the Chmapion plugs:
Chart

jim warehime · Nov 30, 2016

Champion D89D was replaced with the champion 543 are getting hard to find as they are out of production. The 543 crosses over to a autolite 388. Both the champion and autolite are 18 mm thread. I have been running autolite in my md's and super md's with no issues and the autolite plugs are alot cheaper $2.50 ea vs $11 ea for the champions. As stated magneto fires counter clockwise on the diesel.

SW EM · Nov 30, 2016

Thank you all for your replies. I'll keep you all updated with any progress I make. This tractor will be one I tinker with in my free time while finishing up my Ag Engineering degree at ISU. It's missing quite a few linkage pieces...and some fuel lines.

jim warehime · Nov 30, 2016

You will need to find the missing linkage then once installed go thru and set the linkage and related parts to spec. To do this you will want a IT #8 manual, do not try and run the engine until every thing is together and set to spec. Good luck and keep us posted on your progress, what year is your md?

SW EM · Nov 30, 2016

Yes I have that manual from when I worked on our SMTAD. This MD is a 1950 model. Are you looking for a specific year? I saw you asked another guy that in an archived post.

jim warehime · Nov 30, 2016

No, just like seeing what years are still out there. Pretty much all the md's out there still are 47-51 with the large majority being 50 and 51. They didn't build many prior to 47. I have a 41 and 51 md along with a 53 smd and smtad. They are really neat tractors and fun to play with.

SW EM · Nov 30, 2016

I was looking at the M serial numbers on here, and it would be cool to find a 1944 MD. Any wartime tractor would be neat...

jim warehime · Nov 30, 2016

I have been looking for a 42-44 md for a few years just to do a stripped down wartime model on steel with no electrical system or hydraulics. Would also like to find a 52 super md as well. I think a wide front md on full steel would look cool.

SW EM · Nov 30, 2016

Yea that would be cool to take to shows. If I ever see one I'll post a picture of it! Do you have any pics of one?

jim warehime · Nov 30, 2016

Just my nf 41.

scott mcintosh · Nov 30, 2016

I use champion plugs for ford 300 hundred six cylinder.Tractor is in the shed so I cant give you part number,But look up 1987 ford 300 hundred six fuel injected engine as those have extended reach.Ben using them in my 450 diesel for twenty years.D89 plugs are to spendy for me.Scott

Brownie450 · Dec 1, 2016

Get the plugs out first & look them over closely.
Dad got our 450D new in 1956, & it still has the
original plugs in it.
When he had it overhauled, the mechanics wanted to
put new plugs in it. Didn't happen.

Dad said the plugs should last the life of the
tractor---as little as they get used.
Jim

SW EM · Dec 1, 2016

Great picture! Looks good the way it is. I would love to find one with that kind of "patina". Yours has the early Bosch pump I see.

jim warehime · Dec 1, 2016

Yes it's the early Bosch A pump, it also has the starting primer on the intake manifold as well.

rustred · Dec 2, 2016

the standard D 16 plugs will make starting hard but once running there is no difference. i did this as my own experiment. but yes, for easy starting u need the long reach plugs. they are about 20.00 each.

Farmall MD spark plug size

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