Fuel problem, maybe carb 1970 ford 2000

Ford2000guy

New User
When I start up my tractor, it will "buck"
when I put it in gear, then it will level
out and ride smooth. Then throughout
driving, it will occasionally "buck" or act
like it wants to die. Sometimes to fix this
problem I will barely pull out on the choke
or throttle up a little. This sometimes
fixes it as well. I cleaned out the fuel
bowl. When I cleaned out the fuel bowl I
made sure that fuel came out of the fuel
inlet line. It streamed out pretty good. I
know gas is getting to the carb because I
unscrewed the brass plug in the bottom of my
carb and gas came streaming out. Is a carb
rebuild the next step? I have a Holley carb
12R-3589B.
Also what it the vertical black cylinder to
the left of the rubber hose connecting the
carb to the intake tube?
 
Here is the picture I forgot to attach.
a157390.jpg
 
I'm not a carb man.
But I do like to fish.
So I treat those Holleys like I do some fish - catch and release. I release them into the nearest, swamp, ditch, trash can or scrap pile.
Then I go spend the dough for a new Zenith.
New Zenith will use more fuel. It'll also get rid of all those niggling darned 'Holley problems' and make a man out of your tractor again.
 
That is a air restriction indicator. A red band will show in the little window if your air cleaner is getting plugged. The button on top is a reset.
 
Ultradog, that is the best description I've ever read about this, this is a link I'm saving. And for the OP, when Ultra says it'll use more gas, keep that in context. If you're not using your tractor day-in/day-out, you're probably not going to use more than a few bucks more. If fuel burn really is important, get a diesel.

Have had our Zenith for at least 7 yrs, never ever had to fiddle with it, and it has always started, even after sitting for awhile (like between end of mowing & first snow plowing). Zeniths aren't cheap but, for my money, well worth it.

Counterpoint - there are a couple of Holley gurus on here who love 'em. If you can learn enough from them to get yours in shape, props to you.
 




I haVE never had a tractor buck... but I have had them cut out...

The holley has an accelerator pump on the bottom of the carb bowel, that was used to give the carb a sudden burst of gas when applying quick throttle, as when the tractor loads up and need more gas.. This accell' pump being in the bottom, was subject to any water as the water settles to the bottom. and then the water would rust/ corrode/ freeze up the pump, making it unworkable.

the acell' pump allowed the holly to run a closer jet for proper work but also allow it handle sudden loads. this means that the mixture was closer to correct, but it could handle power when needed. Cheaper carbs did this by running the mixture richer. Therefore they burned more gas, left the plugs covered more with soot and carbon.

Once the accell' pump is rusted up, its all but impossible to get it out to clean it and free it up.

So.. you can simply richen the holley up so its like a zenith, or live with the stumble when the governor suddenly opens the butterfly, making the mixture go lean, for a second or two.
 
Premise: Never address potential carburetor issues unless and until you are certain that the ignition is spot on.

That said, your symptom sound like lean tip-in, i.e., a lean mixture upon throttle opening.

The Holley carburetor has a vacuum operated accelerator pump. This feature allows the jetting to be set leaner resulting in less fuel consumption but lean tip-in will result if it is not working, as is common with 40+ year old carburetors. Corrosion and/or dirt can cause the pump to become inoperative. Additionally, a failed vacuum advance motor affects engine vacuum, which will affect pump performance even if all else is well. It is not uncommon for these old tractors to have inoperative vacuum advance motors (verify that ignition is spot on before addressing carburetor issues).

The Holley carburetor is more sophisticated than other tractor carburetors of the era and not as simple to overhaul as a result. If you decide to overhaul yours, bite the bullet and buy your overhaul kit from CNH. It will be expensive but it will have the correct gaskets. Take both tractor and carburetor serial numbers with you to CNH as they will need one or both to order your kit. Aftermarket kits often (usually, always?) have incorrect metering block gaskets, the use of which will result in more problems than you already have. You will also likely find that the float bowl gasket(s) in the aftermarket kits will not tolerate any amount of ethanol.

If you properly overhaul your Holley carb, you will be pleased with the result. If you give it the short shrift, you will likely end up replacing it with less fuel efficient Zenith carb in the very near future.

Be advised that the Holley carb is sensitive to float level and the setting is speced to the 64th inch.

Dean
 
I agree with the others on the accelerator pump, yours also has a vacuum advance, which can give similar symptoms if bad.
 
I had 6 of those Holleys here.
2 years ago I brought a whole pickup load of Ford parts to an auction and got rid of them to make room.
The holleys went as one lot.
They brought the minimum bid - $5.
The rest of the parts brought ok prices. Not great but ok.
If, aside from a few "Holley gurus", people thought those carbs were worth more than scrap they would have gone higher.
 
So I am assuming there should be a through hole into the air restriction indicator from the pipe going up to the intake? Right now the whole is completely plugged that the air restriction indicator is screwed on to.
 

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