Newbie with a 420c - Power Question

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lrolla
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Newbie with a 420c - Power Question

Post by lrolla » Thu Aug 09, 2007 10:23 am

Purchased a 420c on ebay about a month ago. Still goes against my better judgment buying something without getting a close look but I asked a lot of questions, felt comfortable with the answers and it turned out ok.

Now that I've had a chance to use it a couple of times I'm wondering about the power of these tractors in general. I find that it chugs along just find but doesn't have much torque and when pushing a load or crawling up a steep hill. It doesn't take much before it starts to bog down and almost die. It almost feels like if I could only get more rpms, I would get into the torque power band and it would do just fine. The governor prevents me from going any higher on the rpms so I don't know if my theory is right.

I was going to start with a tune up and see what I get. It runs great but I'm just not sure about the power. Does anyone know when the dwell should be on the points? I know the gap but would prefer to work with the dwell to get it right on.

Thanks,

Larry

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Lavoy
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Post by Lavoy » Thu Aug 09, 2007 11:13 am

There are a host of things to check on, timing, fuel mixture, compression, high idle speed to name a few. Extra RPM will gain you little other than potential engine damage, I would not go that way.
Lavoy

lrolla
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Post by lrolla » Fri Aug 10, 2007 9:11 am

Thanks Lavoy. I'm with you on the suggestions. I have the tune up parts and will start with that and a compression check.

Larry

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hunter41mag
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Post by hunter41mag » Fri Aug 10, 2007 10:15 am

Larry,,

Be sure to check base ignition timing and that you are using
the correct marks on the flywheel. Another thing to check
(if equipped) is that the timing advance weights and springs are
functioning.
Don
Eastern PA
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Stan Disbrow
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Post by Stan Disbrow » Fri Aug 10, 2007 12:23 pm

Hi,

Watch your fuel as well. I ran into a problem with that last year. I used to buy 93-94 octane as I felt it stored better. Well, they changed the fuel formulation for emissions reasons around here and then the old engines lost a lot of power as a result. I went back to 85-87 octane and, gee, the power came back.

I actually accidentally figured it out. The 420c had lost power, but my old 'M' was still fine. While using the 'M', I had to refuel and then *it* lost power as well. So, after dumping all the 'new' 93 into the wife's pickup truck and reloading with 87, the problem magically went away.

Note that I messed on the fool 420c for two weekends trying to find the reason for the loss of power before I figured it out.

After thinking about it for a while, I tried a 50/50 mixture of pump 87 and 100 octane unleaded racing fuel and noted a significant improvement in running in the old JD 2-cyl engines.

BTW, I run the 100 octane straight in my 2-cycle engines. It runs cooler than pump gas, and it also has this wonderful property of never varnishing, so one can leave the gas in the tanks and carbs for months and the things always start right up. ;)

The only problem with racing gas is it's costly. It's up over $6 a gallon these days. However, since I don't use any of the old iron on a daily basis, it doesn't hurt the wallet too badly. One of the local gas stations caters to the local racer crowd, so they have a pump for 100 octane, which makes it handy. :)

Stan
There's No Such Thing As A Cheap Crawler!

Have: '58 JD 420c 5-roller w/62 inside manual blade
Have: '78 JD350C w/6310 outside manual blade
Useta Have: '68 JD350, '51 Terratrac GT-25
Also Have: 1950 M, 2005 x495, 2008 5103 (now known as 5045D)

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Tigerhaze
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Post by Tigerhaze » Fri Aug 10, 2007 1:18 pm

A lot of the Super Unleaded around here in the the Midwest (93 Octane) is 10% ethanol- I don't know if that is a reason for the power loss or not but it seems like it could be an issue.
(1) JD Straight 450 crawler dozer with manual outside blade; (2) JD 2010 diesel crawler loaders; (1) JD 2010 diesel dozer with hydraulic 6-way blade; (2) Model 50 backhoe attachments, misc. other construction equipment

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Stan Disbrow
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Post by Stan Disbrow » Mon Aug 13, 2007 8:47 am

Hi,

The Ethanol won't help. Around here they stuck MTBE in to the 93 and that's when it went bad as far as my 2-cyls go. The 87 they don't mess with as much as there are still a lot of older cars for the politicians to think about when it come to election time. ;)

Stan
There's No Such Thing As A Cheap Crawler!

Have: '58 JD 420c 5-roller w/62 inside manual blade
Have: '78 JD350C w/6310 outside manual blade
Useta Have: '68 JD350, '51 Terratrac GT-25
Also Have: 1950 M, 2005 x495, 2008 5103 (now known as 5045D)

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klittle
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420 power question

Post by klittle » Mon Aug 13, 2007 3:38 pm

When we bought our 420 some years ago, we had a problem with power also. After we put in new plugs, points and condensor, and done the carb, most of our problems were gone. You might want to check the throttle shaft where the governor connects to the carb, ours was broken and the governor couldn't open up the butterfly fully. A new shaft came in the carb kit.

Oldhousehugger
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Power loss on gas engine

Post by Oldhousehugger » Fri Aug 17, 2007 1:45 am

Like many of you I have rebuilt carbs out of necessity many times. One of the most exasperating was a Briggs And Stratton 18 HP downdraft which just wouldn't run right. I must have pulled it apart 4 times until I finally put on my magnifier glasses (I’m sure none of you need them yet).

With the added close up acuity I was able to see a little tiny opening in the throat of the carb which I proceeded to ream out with an insulin needle which happened to be the right size. Voila. It ran great after that.
I sold that dog to a guy who I guess is still mowing grass with it. Lesson learned, Dirt gets in the smallest spot and jams there and won't let the fuel or air thru as necessary.
I’ve run Coleman fuel in my old Homelite and it goes like a raped ape until the rubber fuel lines and gaskets dissolve. Kind of cool and kind of expensive. Anybody tried mixing a little diesel with their gas to get more octane and more BTU’s. The old multi fuels started on gas and then switched over to kerosene after they warmed up. It might work.
John

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CCWKen
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Post by CCWKen » Sun Aug 19, 2007 10:34 pm

I think KLittle hit the nail on the head. Check the governor. Mine just started bogging down under load and it has new everything. After hooking a wire to the throttle for a test, the thing couldn't be stopped. I haven't gotten into it yet but I'm pretty sure it's the governor.

They operate similar to a lawn mower engine. As the rpm drops from a throttle setting, the governor opens the butterfly more to compensate for the load.

lrolla
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Great information

Post by lrolla » Mon Aug 20, 2007 9:25 am

Thanks all for sharing your JD experiences.

I'm going to start with the tune up and see what that gets me but I'm sure the carb will be close behind based on the sediment I found in the glass bowl. I'm also going to check out the governer linkage.

Broke the generator fan belt this weekend so I'm chasing another problem at the moment. :)


Larry
Larry Rolla

lrolla
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Post by lrolla » Tue Sep 04, 2007 9:48 am

Just to close the loop on this thread. I put fresh plugs, points and condenser in the beast and can't believe the difference.

I'm able to drive around in second gear without a problem when before it would bog down and I had to revert to 1st. :D

Thanks for all the suggestions.

Larry

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