Carburetor adjustment

There are two adjustments on a 9N Ford Carburetor , one for fuel and one for air. My tractor run a little rough and I did some adjustments on the carb to where it ran smooth but it seems I have lost a little power. I?ve made many adjustments and this is the best it?s ran. What adjustments should I make to increase power.

Power is affected by the setting of the main jet, but it is not easy to adjust for noticeably more power without having it on a dynamometer. You want to first be sure that your timing, spark and valve adjustments are exactly right, and then put it on a dyno if you can gain access to one. If you can't get it on a dyno your best bet is to get set up to mow or whatever job you have where you can notice an increase or decrease in power as you have already, then stop and adjust a little.It will be unlikely that you will notice a change unless it was way out. When under a heavy load if you are seeing black smoke it is an indication of running rich. Another possible test is to pull a loaded wagon of some sort up a good grade.

The problem with a carburetor is there is also adjustments on the inside too. The float has to be adjusted right and there is a metering rod which regulates the fuel volume.

Like showcrop said, everything has to work together.

Before adjusting the carb be sure everything else is as it should be. A commonly overlook area is the air cleaner. There is a wire mesh filter above the oil reservoir that needs to be cleaned periodically. Also check for mud dobbers, bird and mouse nests.

There are many factors that affect mixture. Be sure the engine is up to operating temperature, the spark plugs are fresh and clean, the oil has been changed and not contaminated with gas. It may even be necessary to tweak the mixture according to the daily operating conditions, as in a hot dry day will need a leaner mixture than a cold damp day.

The top adjusting screw is strictly for idle mixture. It needs to be adjusted at low idle RPM, down around 400-500. It will have little to no effect on the top end power. However, if it makes no difference, something is clogged internally, or the engine is not healthy enough to idle at low speed.

The lower adjustment is the main jet. That's the one that fine tunes the mid-top mixture. The best way I have found to adjust it is to bring the engine down to idle, then suddenly open the throttle while observing the response and exhaust. Keep doing this while closing the main adjust about 1/4 turn at a time. The engine will begin to stumble or die. At that point, begin backing the main out 1/8 turn at a time, repeating the test until the engine will take sudden throttle without hesitation. A single puff of black smoke is desirable.

From there, operating under load, observe the performance, exhaust, and fuel consumption. Black sooting means still too rich, turn it in slightly. Loss of power means too lean. Fuel economy will be best when the mixture is right.

There are 2 adjustment screw but you have them named incorrectly. The one that sits higher up is the idle adjustment screw and it is in for rich out for lean. Starting point for it is 1.5 turns out from bottom.
The lower adjustment screw that sit at a 45 degree angle is the main jet and starting point is 2.5 turns out form bottom. As per the instruction sheet that comes with the carb kits I buy.

Then for there you adjust the main jet for to most power and NO black smoke

Soudsgood

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