Zenith Carb on '69 Ford 2000-Float setting?

[Bob_Young]

Need to know the correct float setting for this carburetor....the measurement plus from where-to-where the measurement is taken. Would also like to know the suggested initial setting of the idle mixture screw.

Went to work on getting my sidelined 2000 running. Found that my Dad had replaced the Holley with a Zenith back in the late 90s sometime...and had no luck with it. The reason for that, I found, was that the Zenith float was a leaker and filled up with gasoline. Gasoline ran right through the thing and drained onto the ground when I first tried to run it.....Same thing he said the Holley was doing, as I recall.

Put in a new float and got it running, but it now seems to be very lean. Have to run with the choke half out to keep the RPM steady. Both my IT manuals address the Holley, no mention made of the Zenith. No other paperwork has been found.

BTW this is the 3 cylinder 2000. Soundguy, this is the same carb you linked me to in ytmag.com the other day....13913 is the number on the tag.
Bob

 

[Soundguy]

Try 1/4"

I've mainly messed with the MS carbs.. but do have a zenith on my 850.. and it may well be the same as your 3 cyls..

I use a 1/4 drill bit as a gauge... works great.. Also.. flaot setting is not as fatally specific as you might think... as long as you get it close enough that it lets gas in the bowl when empty, and does shut the needle off before gas overflows into the main chamber past the venturi.. then it should be fine..

Check for holes or that it doesn't hang up onthe sides.. etc..

Soundguy

 

[Bob_Young]

Thanks, Chris. I've got it home now, so can tear into it at any time. I'll try the quarter inch drill later this week.
Bob

 

[bjr]

Hey guys, maybe I can sneak in a carb question on the same thread. This on a 430 Case gas tractor W/148B engine I think. I don't remember exact model of carb. I think its a MS. The carb. was just rebuilt and intially ran great. Now only way it runs is with the choke on. Could the float needle be stuck closed? Or is this a symtom of plugged fuel line? What end of the tractor do they start on? It's the neighbor tractor and his mechanical aptitude is marginal. Carbs are not my specialty either. I usually have extra parts left over they look more like park fountains leaking and spraying gas. Maybe I'm exaggerating a little but just don't like small parts detaillly type projects, so I'm not getting to close to this tractor. bjr

 

[Soundguy]

Needs choke to run is a classif symptom of a vacume leak OR fuel obstruction.

So yes.. crub in the float needle, fuel line.. fuel strainer.. etc.

Or a air leak in the carb.. say around throttle shaft.. or a carb 'halves' gasket.

to decide which:

Get her outside, start her up and get her running.. choke on.. etc..get a plumbers propane torch.. don't light it up turn it on full blast.. and wave it al around the carb.. if the engine speed/sound changes.. you found your vacume leak.

Soundguy

 

[rgc53]

Mr Young,

I had a Ford 3000 with a zenith card.
I had a similar problem, a mechanic told me how
fix it! take the arm that holds the float and
bend it up a little bit ,what is happening is as
the fuel enters carb. the float rises too soon
and pushes the needle up into the seat closing the door
the engine is starving for fuel ,which is why you have
pull the choke , give it less air for the amount of fuel the
engine is getting! if you bend it too much the engine will
run rich and foul plugs , try a quarter inch to start.

 

[rgc53]

I assume your 2000 has the same engine as the 3000
a 158 c.i. , the Ford manuel says the idle should be 650 R.P.M.
make sure your timing is right it affects idling speed
timing is 18*b.t.c.

 

[Soundguy]

IE.. adjust his float to correct level..

Sounguy

Mr Young,

I had a Ford 3000 with a zenith card.
I had a similar problem, a mechanic told me how
fix it! take the arm that holds the float and
bend it up a little bit ,what is happening is as
the fuel enters carb. the float rises too soon
and pushes the needle up into the seat closing the door
the engine is starving for fuel ,which is why you have
pull the choke , give it less air for the amount of fuel the
engine is getting! if you bend it too much the engine will
run rich and foul plugs , try a quarter inch to start.

 

[Bob_Young]

Finally got the tractor off the trailer today and into the shop. Haven't had a chance to monkey with it yet this week....setting the float level will be the first priority. Maybe tomorrow.

Chris:
That propane torch idea for finding vac. leaks is a winner. Gotta keep that trick in mind. That could very well be the problem. There could be gum or crud in there as well, though I've poked and prodded where I could. It's been sitting since '99 or 2000. The main jet was totally clogged when I first got into it.

rgc:
Yep, it's the 158 c.i. 3-banger. Same engine they used in the 3000, according to the IT manual. With the choke all the way in (off), the engine runs but keeps surging between about 900RPM and 1400RPM. Apparently it starts to die and the governor opens the throttle to keep it running resulting in the surge to 1400RPM; then the governor backs off. So RPM constantly bounces up and down. This carb doesn't appear to have an accelerator pump, but I may have overlooked it. Running lean without an a-pump, I'd expect it to bog when the gov. opens the throttle.

Whatever's wrong, the thing starts right up....but then it was always good that way.

One really weird thing: The hourmeter in the tach now reads 1528 hours. Last time I ran it in the late '90s I definitely remember seeing over 2200 hours....got no clue on this one.

Thanks for the suggestions, guys.
Bob

 

[Soundguy]

Surging can sometimes mean lean mainjet..

That propane trick usually works, .. I've seen people do it with starter fluid.. but I usually don't reccomend that one due tot he increased fire hazard.

WD40 also works ok as the juice temporarilly seals the leaky gaskets.. etc.. however propane torch is the easiest with least mess.. etc.. and quite safe in open air as it takes a specific concentration of propane buildup in the atmosphere before it becomes explosive.. etc..

Soundguy

soundguy

 

[Bob_Young]

Well, raising the float didn't help. Raised it a good eighth of an inch. Still need to have the choke halfway out to have it run smoothly. The float seemed high to begin with....a good sixteenth less than your quarter inch benchmark, Chris.

Also tried the propane torch trick to no effect. I was still suspicious of the vacuum advance line to the distributor, so disconnected that and put my finger over the fitting at the manifold end. Had no effect, finger in place or not.

There appears to an acceleration pump built into the carburetor that's activated by a sudden drop in manifold vacuum. There's a spring loaded rubber diaphragm beneath the carb. bowl that forms the bottom side of a chamber that's connected to a nozzle that discharges upstream of the venturi. The discharge nozzle was clogged; I cleaned it out and can blow Gun Scrubber through it in the discharge direction, but cannot see through it or push a wire through it. It may have a ball check valve in it's base.

I have not figured out how fuel gets into the chamber controlled by the diaphragm. It did have some nasty old gasoline in it when I took it apart and I had to clean up everything in there, but the only passage from the carb. bowl I've found, ends in a small chamber that is blocked off by a brass screw. There's another mysterious brass device in the top of the chamber that I can't describe...gas may get in that way. However fuel gets in, it can't be just a simple passage....the discharge nozzle is below the level of fuel in the bowl.

There appears to be two jets of about the same size in series between the bowl and the main discharge nozzle....one at the bowl exit and another a bit further along angling upward toward the discharge nozzle. Didn't write down their sizes, will do so next time I'm in there. I believe fuel for the idle circuit is taken off somewhere between the two jets....this is something I have to confirm. If not, I don't see the purpose of having two jets in series.

Used my new gaskets when it went together this time. If anything it's slightly worse now when the choke's all the way in. It seems to stagger or bog when the governor opens the throttle to recover from the RPM drop.

After this latest go-round, I too began to wonder whether this thing needs a twist drill run through the main jet (whichever one it is). Could be that this is sort of a generic replacement carburetor and needs a bit of setup for the engine it's put on.

Sorry this is so long and thanks again for the suggestions.
Bob

 

[Soundguy]

If you have the 09D03 zenith on that unit.. ( 65-74 oem )

Then i have an exploded diagram for you.. and a small parts list.. Unfortunately most parts are NLS.

PM me with your fax number and I'd be glad to fax on my nickle to anywhere in the CONUS.

Soundguy

Soundguy

 

[Soundguy]

I wouldn't suggest boring out the main jet... that carb should be sufficient for the 158 ci 3 cyl.

My only guess would be is if the main and idle ject can be swapped. On some MS carbs you can do that.. etc.

soundguy

 

[rgc53]

When i installed the zenith carb on my Ford 3000 the
engine ran very well , idled at 650 rpm , you should
consider taking the carb. apart and soaking the pieces
in carb cleaner!
Also check the length of the rod between the govenor
and carb , the rod length is adjustable and critical ,
if the rod is too short it will cause the engine to run at
high idle and the govenor to surge , the it manuel will
give you directions , there are a number of steps to
adjust all linkages!

RGC

 

[Bob_Young]

Good tip, RGC. I'll look into the governor rod adjustment. I wouldn't have thought of that. Thanks. I think this thing is due for the carb cleaner bath as well.

Chris, this carb is not the OEM Zenith AFAIK. It's a replacement; Part No. 13913. It's among that list of carbs & parts that you linked me to at ytmag. There, the number is at the very end of one of the carb descriptions. On the carb itself, there's a little metal tag bearing the number. Could be it's similar though. There's no fax here, but I'll PM you a number at work if this doesn't show signs of turning around. Thanks for the offer.
Bob

 

[Bob_Young]

Update for anyone interested:
Disconnected the governor yesterday to try running it while manipulating the throttle by hand. Did this to take the governor variable out of the equation. It would not hold a stable RPM unless the choke was halfway out....same as it was doing with governor in the loop. With choke full in, throttle had to be operated much the same as what the governor had done to keep it going. Yet, when operating with choke all the way in (and RPM going up and down), there was a very strong smell of partially burned gas in the exhaust....smelled like it was running rich, or the fuel wasn't being completely burned.

I'm beginning to suspect that a partly clogged air bleed is preventing proper fuel atomization. With choke out, the air pressure balance may be altered enough to pull more more air through the bleed or turbulence from the partly closed choke plate may help atomization or.....?

Anyway, next time in the float's getting lowered back to what it was. Then the carb's getting a good bath and a checkout of every passage.

Although interesting, this underlines why I find new equipment much more appealing in my declining years. The time spent solving little mysteries in the old stuff is better spent doing something productive.
Bob

 

[Soundguy]

Choke usually indicates fuel obstruction.. or vacume leak... in this case.. I'm betting on fuel obstruction.. the dip/cleaning will be good for it.

Soundguy

 

[Bob_Young]

Update on this:
Soaked the carb in a bucket of cleaner for a couple of days, put in a new gasket set and lowered the float back to where it was. It runs OK now.

On disassembly, I noticed that one or two tiny holes in the side of the fuel delivery nozzle were plugged. I think these holes admit bleed air into the nozzle fuel stream to help atomization. The holes in the upper section of the nozzle were open, but those in the bottom section were not. Don't know if that's what caused this problem, but it was the only issue I could see.

Now it's on to the rim rot problem. New rims and rubber are next.

Thanks for the help and the ideas.
Bob

 

[Soundguy]

Good job.

soundguy

 

[shealray]

Try 1/4"

I've mainly messed with the MS carbs.. but do have a zenith on my 850.. and it may well be the same as your 3 cyls..

I use a 1/4 drill bit as a gauge... works great.. Also.. flaot setting is not as fatally specific as you might think... as long as you get it close enough that it lets gas in the bowl when empty, and does shut the needle off before gas overflows into the main chamber past the venturi.. then it should be fine..

Check for holes or that it doesn't hang up onthe sides.. etc..

Soundguy

I also have a 850 with a zenith carb, but after running 2 hours the tractor stops and I hit it on the side of the carb tractor runs. My guess the float is sticking. I am new to carb rebuilds so is there a easy way to fix a sicking float. Maybe carb cleaner ? I do not know how to identify the Zenith carb for a kit. Also could the glass bowl cause this issue. Thank you for your help.