Another Carb problem

Still working on my 8N, it's a work in progress. It's running
good, but decided to rebuild the carb this early fall, it was
leaking like a sieve, worked with guy who is a master engine
rebuilder, got the rebuild kit along with new float, cleaned
soaked painted and put all new parts in it, had problem with
float but got it to work, had to put a washer under the idle mix
screw because it was almost smaller than the spring. Finished,
got it home started right up,and adjusted the best I could with
the stone knifes and chisels I have and manuals. The only
problem I noticed was a hesitation when accelerating, but
figured I'd get to that later. Everything was working good until
I decided to start it in the colder weather, like a day ago. The
old un-rebuilt carb use to to start no problem, rebuilt not so
much. I tried and tried, choke no choke, then decided to pour a
little gas down the air intake, started right up. Then decided
to work on the accelerating problem while I had it running,
noticed if I pull the choke about half way no more hesitation,
is the rebuild kit no good ideas?

If pulling out the choke a little fixes your hesitation then the carb is set too lean. Just turn the main jet screw out 1/4-1/2 a turn and is should resolve that. You should also then set the fuel/air mixer at idle.

I've already tried that, even turned it out 1 whole turn still
the same, are the rebuilt kit needle valves different?

So, you did or didn't rebuild your OEM carb? I'm lost. ...decided to rebuild the carb... then ...The old un-rebuilt carb use to to start no problem, rebuilt not so much... Where was it leaking from? Sometimes when the Valve Stem seal wears and leaks, and it will eventually, the fuel can drip down the line and settle on the carb itself thus appearing the carb leaks. Solution is to buy a new Valve Stem ($6-$8) and replace - do not buy a whole new Sediment Bulb unit, not needed. Get a 9/32 drill and use as you GO Gauge for the float level, set to the nearest point, closet to hinge. Test carb for leaks BEFORE you fire up engine. Use you manuals for setting main and Idle mix screws. Adjustments need to be made once engine is up to operating temp, and only make 1/8-1/4 turns at at time, then you need to WAIT til engine catches up to speed before continuing. Some Einsteins think they will use a rubber, nylon, copper, plastic, aluminum, or other non-oem style fuel line - WRONG! You need the proper 1/4 Steel fuel line with special fittings. Thread size on brake and fuel lines is 7/16-24 UNS ---- so if anything else is used, will muck up the connection and cause leaks. Same on teh line end into Sediment Bulb. The brass elbow and drain plugs are an NPT size so same goes with them. You also do not need to install an additional fuel filter - a total waste IMO. There are 3 filters in the OEM fuel system as it is. The brass fuel inlet elbow at the carb needs to be removed periodically and cleaned. There is a fine mesh screen on the end of it that fits up into the carb when installed. Many fellas do not know this and fail to keep it clean. Here's what to do: Work with a cold engine. Get correct parts first of all and toss any non-OEM parts away. R&R the carb per manuals and rebuild kit instructions. Settings should be done at 400 RPM so a working Proofmeter is a big help. Before doing any testing with a live engine, do teh Fuel Floe Test. If you rebuilt the carb correctly the test should pass unless there is an obstruction on the Bulb, tank, or a plugged vent.

FORD/M-S N-SERIES CARB FUEL INLET ELBOW:



MARVEL-SCHEBLER TSX CARBURETORS FORD TRACTORS HOW TO ADJUST -by Bruce (VA)

When adjusting the carb, turn main jet out 1-1/2 turns and leave it. Then adjust side pointing idle mixture screw to fastest idle, not smoothest. This procedure has to be done when the engine is really warmed up and often takes 2 or 3 tries. When you turn a screw in or out, watch how may turns you go, best to only go 1 turn at a time, then WAIT for the engine RPMS to catch up. The proper method is to make adjustments while under load and at certain rpms, but early 8Ns have no Proofmeter to show R's so best guess scenario takes over. Both Ford and Marvel/Schebler say to set both the side-pointing idlemix {Idle Mixture Adjustment Needle} and the down-pointing main jet {Main Power Mixture adjustment Needle} to 1-turn as a starting point. I set the down-pointing main jet {Main Power Mixture adjustment Needle} to 1-1/2 turns and don't fool with it anymore.

Then adjust the side-pointing idlemix {Idle Air Mixture Adjustment Needle} for fastest idle; not the smoothest idle. Next, adjust the behind the carb idle-speed (throttle) set-screw for very slow 400-rpms idle. Do that idle mix {Idle Air Mixture Adjustment Needle} adjust for maximum idle at least 3-times. Do it like this:

1. Adjust idle mix jet {Idle Mixture Adjustment Needle} until RPM increases

2. Adjust idle-mix set screw {throttle idle-speed set-screw} until the engine nearly stops (as slow as you can get it unless you have a tach that tells you 400 rpm)

3. Grasp the rod between the carb & governor & twist/shake it slightly; the slop in these rods often stops the adjustment cam from moving.

Repeat steps 1 - 3 three times with about 10-15 minutes between tries.

Remember the side-pointing idlemix {Idle Mixture Adjustment Needle} is out for lean, in for rich.

I don't let my N's run dry. The M/S carb has a cast iron bowl & it will rust when it gets dry. Running aluminum carbs dry is ok.

The Main Power Adjust needle is CW for reducing fuel (leaner) and if fully functional will shut off all carb fuel (even idle) when screwed in fully CW to it's seat. This leans it to point that engine dies. You say that this results in backfire. Is that correct? Just before all the way in (so lean it just barely runs, I don't see that you should observe a rich-condition-black-smoke at this point. Do you see that at this point? The Idle Mixture Adjust needle is just the opposite, that is CCW leans the idle mixture. That is because the Idle Mixture Adjust needle controls AIR, unlike the Main Power, which controls fuel. More AIR (same fuel)=leaner idle mixture. CCW=more air=leaner.
Main Power needle is generally not very sensitive except near fully closed (full CW), whereas the Idle Mixture needle is more sensitive.


Tim Daley(MI)

It is an original OEM carb. It was leaking out the air intake and also could not adjust the throttle idle, the screw would not line up with the stop, plus it looked really bad. So I took the advise of people on here to rebuild the original. But I guess maybe not all rebuild kits are the same. Just a dumb question, the idle circuit is not in play after a certain rpm, is that true, if so the main jet would cause the hesitation or a fuel restriction is that true?

something is wrong; you shouldn't need a washer under idle mix screw. Are you sure you used the right one? The Main Screw is a larger screw and some kits only have the Main and idle Mix but no throttle spring so always check a new kit and save old parts. If you want, I'd be willing to look at your carb setup and see what I can do if you want to send it to me -email is open. Maybe this will give you some confidence of what is possible...


THINK YOU HAVE CARB PROBLEMS?

This was the worse carb I ever worked on. Tractor had sat out in a field for 50 years. Believe it or not, I was able to resurrect the unit and once done, ran perfectly. Lots of sand/bead blasting, tumbling, and soaking were required but it ran just fine after.


Tim Daley(MI)

Gas thru the air intake throat usually is a float issue - not set right. Get it apart, again, and use your 9/32 drill as your GO-GAGE to set float level to nearest touch point, by the hinge. New manuals state to use 1/4 as the GO GAGE setting. OEM Specs show there was a gage you could get to set float with .26 as the GO and .297 as the NO-GO. I like 9/32 (.281) as it is close to the mean value. Is the float needle valve and seat right? Are you using the newer Vitron Needle with the extra clip? Is the clip attached right? Go thru entire unit, again, and figure out why you had to add a washer under spring. Again, sumthin' ain't right. Once all is right, set main and Idle Air to specs, assemble, test fuel flow, then start and make tweaks as needed. Why would the idle screw not work after a certain RPM again?

CARB

FORD 9510 OEM CARB NEEDLE & FLOAT STYLE:

FORD 9510 AFTERMARKET CARB NEEDLE & FLOAT STYLE:







Tim Daley(MI)