Couple of questions about 1957 420W

mr.precision · Dec 30, 2017

Recently brought home a pretty nice 420W that hadn't been run in several years. Carb was full of debris/rust, so I cleaned in and installed a kit. The tractor started right up, makes good oil pressure and doesn't smoke. The tractor will not idle well unless the idle screw is turned all the way in. Looks like I didn't get the carb cleaned properly. I could not remove the main jet as it was stuck. Any tricks to getting this out without ruining it? I did get the power jet out OK and cleaned all the passageways in that area.

Second question concerns the throwout bearing carrier. My 40T has a grease zerk visable through the inspection port. The 420 doesn't. The shaft that the assembly slides on is dry. Any thoughts on what's going on? Even the shop manual shows a zerk in there.
Thanks in advance.

M-MAN · Dec 30, 2017

I would suggest going to napa and buying a wider screwdriver. Can't remember if it's a 5/16 or 3/8 but you want one as wide as the nozzle. The edges will have to be
ground so it will fit in the hole. Once there give it a good whap with a hammer and unscrew it. If it's damaged it will have to be drilled out and chased with a fine
thread 3/8 tap. Nozzles can be had for about $30 so it's no bigge if you have to go that route.

I don't think your problem is in the nozzle. That is the load circuit. High speed and throttle response. The idle circuit is where you missed something. On the top side
there is a idle jet and a economizer jet. Both need to come out and be cleaned with a tig tip cleaner. There are three tiny holes in the center of the throat that go to
those chambers. They have to be cleaned/reamed out as well. Yep, you'll most likely have to grind new screwdrivers for those as well. Make sure your venturi isn't
damaged. Once the idle circuit is opened back up you should be able to idle it down to a gallup if you want to.

mr.precision · Dec 30, 2017

Thank you, MMAN.
I did remove and clean the economizer jet and passageways, however I didn't see the idle jet. It is identified as #7 on the JD parts book, but I don't know where it is located in the upper carb body. Will take the carb apart again and have another look.

machineryman1945 · Dec 30, 2017

Use firearm screwdrivers on the jets....this will prevent rounding you can be very careful and put some heat on it an let it cool will aid in removal....[/quote]

Jreb10 · Dec 31, 2017

(quoted from post at 20:58:41 12/30/17)

Second question concerns the throwout bearing carrier. My 40T has a grease zerk visable through the inspection port. The 420 doesn't. The shaft that the assembly slides on is dry. Any thoughts on what's going on? Even the shop manual shows a zerk in there.
Thanks in advance.

As far as the bearing carrier goes, I have seen versions with and without the zerk. If I recall correctly the JD parts book shows a series of revisions to that part number. I suspect the revisions are not complete and/or not accurate. I am guessing here, but I suspect they added the zerk in response to problems and tried to do some retrofits. My 1957 420U had a zerk but the access hole for it looked like an "after-the-fact" addition.

Perhaps others can add their comments about this part.

Couple of questions about 1957 420W

mr.precision

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M-MAN

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mr.precision

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machineryman1945

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Jreb10

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