Model U

avant 1735 · Jan 6, 2016

I just bought a U, I was told it was running then parked then the owner passed away. I was doing some maintenance on it prior to trying to start it. I pulled the plugs and discovered there were two different plug sizes. 2 cylinders have a Chanmpion D9 (18mm width), and the other 2 cylinders had the champion J6 (14mm width).
The heads have different #'s on them, one has 6E3OT(D9 plug), the other has 10A4207(J6 plug). Which head is the correct one? which plug is the correct one? or can I run the tractor with 2 different plugs? Obviously the tractor has been worked on before. Any help would ber gfreatly appreciated.

jnf · Jan 6, 2016

I have a 1950 U that has been on the farm since new. It has two different head numbers with two different plug sizes. I did not discover this until after Dad passed in '83, so I did not have an opportunity to ask him why the difference. I can only assume a head was replaced at some point in time. Anyway, the tractor has run this way for many years with no problems.

avant 1735 · Jan 6, 2016

What plugs do you use?

jnf · Jan 7, 2016

The tractor is 45 miles away at another farm. We leave it there to power a grain auger. I will try to take a look at the head numbers and plugs some time and let you know. Mine is an LP model.

avant 1735 · Jan 7, 2016

My U is an LP engine as well.

Curt Cooke · Jan 7, 2016

Look around either on this site or another for a cylinder head reference chart. I think you'll find that the heads may be the same, just a different # and year. I believe the GE30T head was probably original and I'm sure the 10A4207 is an LP head for a U. Likely a head cracked and was replaced by a comparable head.

mmfan55 · Jan 7, 2016

Web search Minneapolis Moline head specification. You will find a very comprehensive chart on those heads

mmfan55 · Jan 7, 2016

I had time to look it up. 07 and T show same specs on compression ratio and chamber specs.

jr1983 · Jan 7, 2016

Ive run into several like this. A result of a head being more or less the same from 1947 (?) To 1960 (?). As long as this is the worst problem I just used different plugs and called it good.

unc · Jan 7, 2016

My 1950 U also runs two different heads- I thought I was the only one! It's too cold to go out and check numbers, but IIRC, one is a 30 number with a 7/8 plug, and the other is a 10A number with an 18 mm plug (can't remember either number, both are Champions). The point to this ramble is that I worried about this mis-match, even though the tractor seemed to run okay for a beat-up ranch tractor. I pulled the beads, cc'ed the combustion chambers, and miked everything it's possible to measure. Zip difference aside from the different plugs. Reassembled with a bunch of new parts and now " Marlon the Minnie" is my working favourite. My better half says Marlon is staying even if some of the others leave!

MMDEL · Jan 7, 2016

The 30 heads and the 10A heads, if they match on the chart for compression chamber are exactly the same, except when they changed the number, they went to the smaller spark plug and installed satellite valve seats. However over the years many 30 heads have had satellite valve seats installed.
MMDEL

jnf · Jan 11, 2016

Avant 1735, I check the heads on my tractor today. GE30T head has J8 Champion plug, 10A4207 head has D14 Champion plug.

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