8N or 9N Carburetor?

I've had the tractor for a couple of years and just rebuilt the engine. I cannot do much adjustment on the carb to get the tractor to idle smooth and slow. It always seems to idle fast according to the proofmeter. I decided to rebuild the carb, then I discovered it may not be an 8N carb. Should this improper carb be a big concern for me? Shoud I get the "proper" model or just rebuild the one I have?

Your comments and opinions are welcome.

The problem is that the carburetor is either plugged in one of the orifices in the idle system or the two halves of the carb are damaged and not mating closely enough to allow idle adjustment. This condition does not effect the high speed operation but it is impossible to have a good idle if the two halves don't seal.

CARBURETOR WON’T IDLE

First do a thorough cleaning of the carburetor and replace the gasket between the two halves. Be sure that the float does not have any gas in it to cause it not to float properly.

The reason the carburetor may not want to idle is that the gasket that goes between the two halves of the carburetor is not sealing good. This gasket must be tight at the middle where the idle orifice gets it’s gasoline.
Remove the float attaching hinge by carefully prying it up until you can get a small screwdriver under it. Don’t bend the two small blind rivets. They will have to be re used to re assemble the float hinge.

Use a new sheet of 80 grit wet or dry sandpaper that is laid on a hard flat surface and lap both the mating surfaces until it is perfectly flat on both mating surfaces.

Re assemble the carburetor and you should be able to adjust the idle.

Adjust the idle by lowering the RPM and then turning the idle mixture screw in or out until the engine runs at the highest RPM. The RPM is what you will be listening for and not the way the engine runs. MAXIMUM RPM!!! At idle.

First let the engine warm up a bit. With the engine at full throtle,turn the main needle in clockwise untill the engine stumbles (not out) Then turn the main needle out until the engine runs smoothly. Reduce the throttle to idle and then quickly advance the throttle and see if the engine falters. If it does then open the high speed needle a fraction more and repeat until the engine will accelerate without stumbling. Reduce the throttle to idle speed. Turn the idle needle in and out until the highest engine speed is found. This is where to leave it, regardless of how many turns in or out. HIGHEST SPEED! Not sound of engine. The highest speed will be the best idle. Reduce the RPMs to where you want them after the highest engine speed at idle is reached when adjusting the idle needle.