8N Carburetor Adjustments Needed I Think

Can you tell the difference between the idle mixture and main jet mixture screws? Can you tell where the lowspeed idle set screw is? Can you tell which governor rod connects to the carb throttle shaft?

Ford Owners Manual sez to set BOTH the idle mixture and the main jet to 1 turn. Well that works on a new carb on a new engine. I don't think your tractor qualifies. Therefore, I suggest 1-1/2 turns for both the idle mixture and the main jet.

After you get your engine started and fully warmed up (about 15 minutes). Adjust the idle mixture for MAXIMUM rpms, not maximum smoothness, understand? max idle rpms. Tractor idle spec is 450 rpms which is awfull slow to our ears. If your carb is anywheres to being right, you can do it.

Now then, goose your throttle, if engine doesn't respond, enrich the mainjet 1/8 turn. Do it again. You may have to go out to 2 turns on main jet, but no more.

Learn how to read your sparkies color. After idleing for 15 mins, pull a plug, it should be a light tan or light gray color. If it is sooty black your too rich. If it is clean white your too lean. But most important, adjust idle mixture for MAX rpms. Now go mow or plow for a few minutes at high rpms, and pull a sparkie and read the color. That will tell you how well you've adjusted your main jet.

From the black art of adjusting carbs..... ...Dell

I'm just tryin' to get oriented here . . . I'm guessing you're looking at this carb from the side. I'm palming one in my hand right now that I'm getting ready to rebuild, and I'm looking at it like you are. And what you're refering to when you say "the one on the right" with the tension spring is actually the larger screw at the front of the carb. That would be your Power Adjustment Needle (a.k.a: Main Adjustment Needle). That's the one you do the "goose adjustment" that Dell refers to.

The smaller screw in the middle of the carb is your Idle Adjustment Needle. That's the one you adjusts at idle.

The way you start this adjustment is to run the engine until she warms up. Slowly turn both screws clockwise until you feel them seat. Your engine should die. That's OK, we're gonna git her runnin' again.

Now turn both screws COUNTERCLOCKWISE one complete turn off the seat. Start up your tractor.

Now follow Dell's instructions for adjusting the carb. Turn 'em slowly when you're making those adjustments, and train your ears to listen for how the engine RPM are responding.

If'n the idle speed is too high for you to do the idle adjustment, your can turn the Throttle Lever Stop Screw. I think that's the "3rd screw" you're referring to. It's located on the engine side of the carb on the Throttle Shaft. It adjusts the Throttle Plate clearance. FO-4 manual says to set it until idle speed is at 400 RPM, but unless you got a proofmeter on your tracor or a tachometer, that don't do you no good. A rebuild instruction insert I have says to back out the screw until the Throttle Plate will close tightly. Then turn it until it makes contact with the carb body. THEN turn it 1 1/4 turns in. That should get you to about 400 RPM. No warranty implied here.

On the troubleshooting side: If you still lack power you may have some fule starvation. This could be at the cut-off on the fuel tank. Also, the float setting in your carb may be incorrect or you may have a stuck needle restricting fuel entering the carb. May be time for a rebuild. Get you the parts and an Intertec FO-4 manual.

I've have good results running a product I get at the marine store. It's an OMC fuel additive called 2+4. It really helps fight the gunk in the fuel system.

Good luck, and hope this helps.