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1971 Model 120 Restoration

3981 Views 73 Replies 15 Participants Last post by  CBGT
Hello GTT community,

Sorry for the long post here but want to give a thorough intro. I’m currently in the early stages of restoring a 1971 JD 120 and decided it would be a waste not to share progress pics and things learned along the way with people who would appreciate it. I’ve had a hard time finding a lot of info on the 120’s since they were only a two year run, so I hope I can help someone else that runs into the same problem in the future.

Background: the tractor was purchased locally by my grandfather sometime in the early 80’s as a package deal with a trailer. It came with presumably the original mower deck and the original snow blade. He and my father used it to mow several acres of grass every week for decades until after my grandfather passed away and his land was sold. It was also used to plow a 1/4 mile long driveway of snow and was even used to push a lot of gravel around the property. The tractor was always stored outside and was definitely After the land was sold, my father and I continued to use it for mowing/plowing snow over the last 10-15 years, although on a smaller scale and less frequently. The last few years the tractor has sat outside with little to no use and my father recently decided to pass it along to me. The mower has been losing oil quickly for a while now, but other than that it ran fine.

To the best of my knowledge, this tractor has never been tampered with other than my father rebuilding the carb once and some other light maintenance. The engine has never been rebuilt until now and it has never been repainted in any way.

My goal with this tractor is to make it show room quality or as close as it can be to that with my skillset. I have plenty of other equipment to do the things it can do, so I have no need for a worker tractor, although I’ll still subject it to light use.

Pictures to follow
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Do you know if there are any good threads or videos out there on how to do the swap? I.e. is it just the stator and regulator that get replaced or are there other things that would need replaced/adjusted to compensate for the change?

I really appreciate everyone’s help here! This is the first project of this kind that I’ve done so it’s good to hear from folks with more experience.
Assuming the 15amp regulator fits in the same hole on the cooling shroud, I assume you could just bolt on the 15amp stator in place of the 10amp, bolt on the 15amp regulator and go. Probably the same flywheel.
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Assuming the 15amp regulator fits in the same hole on the cooling shroud, I assume you could just bolt on the 15amp stator in place of the 10amp, bolt on the 15amp regulator and go. Probably the same flywheel.
Everything online seems to point to them having the same flywheel. I’m thinking the swap may be my only option if I want to replace the stator. I’ll keep everyone updated if/when I go this route!
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Here's a parts list for that engine:

Attachments

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What type of paint are you using on the larger green and other pieces?
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What type of paint are you using on the larger green and other pieces?
I’m planning on using John Deere branded AG & Turf Green paint. I know that may be a little lighter in color than what was originally on the tractor. I haven’t yet painted any of the green pieces.
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Don't know if they still do, but Deere dealers were carrying both Classic Green and AG & Turf Green (and Sabre Green)

Classic Green
TY25644 340 g (12 OZ) Aerosol
TY25655 946 mL (1 QT)
TY25670 3.78 L (1 GAL)

Sabre Green
TY25613 340 g (12 OZ) Aerosol
Silver Jubilee
TY25675 340 g (12 OZ) Aerosol

Ag & Turf Green
TY26019 12 mL (0.4 FL OZ) Pen
TY25624 340 g (12 OZ) Aerosol
TY25643 946 mL (1 QT)
TY25656 3.78 L (1 GAL)
TY25620 3.78 L (1 GAL) Fast dry
TY25629 18.9 L (5 GAL) Pail


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Don't know if they still do, but Deere dealers were carrying both Classic Green and AG & Turf Green (and Sabre Green)

Classic Green
TY25644 340 g (12 OZ) Aerosol
TY25655 946 mL (1 QT)
TY25670 3.78 L (1 GAL)

Sabre Green
TY25613 340 g (12 OZ) Aerosol
Silver Jubilee
TY25675 340 g (12 OZ) Aerosol

Ag & Turf Green
TY26019 12 mL (0.4 FL OZ) Pen
TY25624 340 g (12 OZ) Aerosol
TY25643 946 mL (1 QT)
TY25656 3.78 L (1 GAL)
TY25620 3.78 L (1 GAL) Fast dry
TY25629 18.9 L (5 GAL) Pail


Yep, they still carry both the Classic and Ag&Turf Greens. There’s a lot of argument on various forums over when and how often Deere changed the colors on their equipment. Some people say there was only one changeover in 1989, others say that the shades have changed multiple times over the years and there’s no public record of when those changes happened. I ultimately decided to go with the Ag&Turf green because it is a little brighter and I like shiny things. And very few people will be able to tell the difference unless it’s sitting next to another Deere painted in Classic Green.
I haven’t painted any of the green parts yet, but if I start painting and decide I don’t like how bright it is, then I’ll just change course and go with the Classic Green.
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I’ve been spending any spare time I get continuing to sand blast, clean, prime and paint parts. Here’s a couple parts that are finished. Sandblasting the parts is totally worth it and makes a great surface for painting. The black Rustoleum looks awesome, but only time will tell how it holds up.

As you can see, I’ve already blasted the air filter cover. I’ve been waiting to prime and paint that until it warms up a bit outside. It gets painted with Deere green paint and I want to make sure the temps outside are good before I start playing with that.

Product Automotive tire Auto part Household hardware Adhesive
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Replacement muffler came in from Hapco today! Looks to be the right size and everything. Super happy I was able to get this and didn’t have to settle for something a little different.

Grey Art Gas Font Cylinder

Automotive tire Wheel Tire Synthetic rubber Gas

Automotive tire Comfort Grey Gas Synthetic rubber
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I’ve been pretty busy lately with other commitments so I haven’t had as much time to work on the tractor, but I’ve still got things cooking. One item I’ve been working on is this heat shield for the top of the engine. It had quite a bit of pitting on it after sandblasting the rust away. I know this is a little over-the-top, but I’m a perfectionist and know it’ll bother me if I don’t fix it. I’ve been priming, wet sanding, then re-priming to fill in the pits. Hopefully they’ll hold up over time with normal use.
Table Rectangle Wood Gas Tints and shades
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We’ve also started fiberglassing the hood. Upon closer inspection, it looks like the original owner may have busted up the leading edge of the hood at some point and used body filler to rebuild it. In the one photo below, that is body filler that is cracking and there’s very little fiberglass underneath it. They did a good job blending the paint, but they would’ve been much better off redoing the fiberglass. So overall the hood will take more work than originally anticipated. I will hand sand everything after building up the fiberglass to get the contours right.
Hood Rectangle Automotive exterior Fender Automotive design

Automotive tire Motor vehicle Rectangle Automotive design Automotive exterior
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After honing the cylinder for a while, measuring and re-measuring, we decided it was time to take the block to a machine shop. The cylinder was too far out of round and it seemed like the best thing to do. The valve seats needed ground anyway and the head needed flattened, neither of which did we have the tools to accomplish. We got the block back and it looks fantastic. The cylinder is already honed, the valves seats were ground and the valves were ground to match. On top of all that, the block is way cleaner than it was when we gave it to them. All in it cost $233, which may be a little steep, but it was well worth the time saved and the tools I would’ve had to buy to do it myself. My goal this week is to get the block painted and primed and ready to start some of the reassembly.

Gas Machine Audio equipment Auto part Wood

Rim Automotive tire Wood Auto part Circle

Automotive tire Motor vehicle Automotive lighting Fender Gas
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The only downside here is that the cylinder was so far out of round (and there was a pretty deep scratch inside the cylinder), that they had to bore it .030 over to get everything back into spec. So this does not leave me much, if any, wiggle room in the cylinder size for a future rebuild. But it had to be done so it’s all good with me.
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And the block has been painted! Again using high temp Rustoleum engine primer and engine enamel. We’ll see over time if it holds up.

Automotive tire Motor vehicle Bumper Automotive exterior Fender

Automotive tire Gas Machine Nut Auto part
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Spent the day today reinstalling one of the main bearings, oil seal, governor gear, valves, and camshaft.

Word of advice to anyone thinking of doing this: buy yourself a cheap valve compressor. You can get the valve keepers on the valves without one, but it takes a lot of time and is a true pain in the rear.
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For anyone who doesn’t know what the inside of a starter looks like, here’s a pic. We took it apart so I can paint the housing and everything and so we could clean the internals up. There was a surprising amount of dirt inside of it.

Automotive tire Gas Rim Auto part Wheel
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Today was a productive day. Did a lot of sandblasting, got some painting done, set the valve tappet clearance, and put the rings on the piston. One surprising find of the day was in the pic below. When looking at the old piston, I noticed a very dirty and difficult to see marking on the face of it that said .010. It seems that this motor was rebuilt at some point in the first 10 years of its life. This was a huge surprise to us as we assumed it was all still stock.
Artifact Fur Rock Font Fashion accessory
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This week I received a 15amp stator in the mail. Based off some reading online and advice on this forum, I had assumed it would be a pretty straightforward swap since the 10amp stator is no longer manufactured. Unfortunately this is not the case. The 15 amp stator is approximately 1” larger in diameter. The 10 amp stator that was in it sat inside the flywheel pretty snugly and the 15 amp, due to being much larger, will not fit inside of it. Pictures below for reference. The old stator did still work so we will just move forward with the old one and I’ll have to return the new one I got.

Wheel Tire Motor vehicle Automotive tire Tread

Automotive tire Fixture Red Automotive wheel system Circle
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Finally sprayed my first green part today! Turned out pretty good, we’ll see how it looks in a couple days. I did this first photo to compare the original color that was on the tractor with modern JD Ag & Turf Green. Keep in mind that the factory paint is extremely old and this thing sat in the sun for a long time. There’s no gloss to it anymore so it’s a little harder to compare. Overall, I’d say it’s pretty darn close to the original and I’ll plan on continuing to use the Ag & Turf paint for the rest of the project!

Helmet Green Hat Personal protective equipment Bumper

Tire Automotive tire Wheel Motor vehicle Fender
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Very productive day today again. Got the crankshaft put in, bearing plate with bearing, oil seal, piston assembly, stator, and a few other things. Also painted the oil pan and part of the clutch assembly. The bearing plate didn’t appear to have been painted from the factory, so I polished it up using White Diamond polish/sealant to make it shine a bit more.

Automotive tire Motor vehicle Rim Gas Automotive wheel system
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