Reassembly
Once all parts have been cleaned and inspected - replaced where needed, proceed as follows:If you removed the throttle assembly:
- Reinstall the throttle shaft along with its spring and felt and/or metal washer. Hook the spring onto the ridge on the carburetor body. Make sure it moves freely. DO NOT lubricate.
- Attach the throttle plate to the shaft with the original screw. Make sure the plate is correct side out and that the hole is positioned on the right facing the upright carburetor from the throttle plate side. As you tighten the screw, slightly rotate the throttle shaft to allow the plate to seat properly - jiggle it a bit at the same time. When properly installed, the plate itself limits the return movement of the throttle. It should be fully closed at this point.
Confirm that the throttle plate moves freely between a fully closed and fully open position - there should be no hint of binding or stiffness.
- Reattach the air inlet pipe with gasket using the two sets of nuts and bolts. Don't forget the metal strip for the governor spring if your carburetor uses this. Tighten securely - 4 to 6 ft-lbs if you use a torque wrench.
Now for the main event:
- Install a new seat if you removed the old one. The new seat goes in groove side first (lubricate with a drop of oil) and can be pressed home with a blunt rod.
- Install the float using the hinge pin.
- Insert the inlet needle hooking the retaining clip on the tab near the float hinge. Check for free movement of the float.
- With the carburetor body inverted, check the float height adjustment. It should seat almost horizontally. For a more precise test, use a 0.210" (#4) drill bit as a gauge across the outer ring of the carburetor body - the float should just touch this. Bend the tab on the float to adjust. (Note: unless you replaced some parts, this setting will probably be fine.)
You can test for proper operation using low pressure compressed air (i.e., by blowing into the fuel hose), or water or gas. Water is safest but you must make sure to dry everything thoroughly before final assembly. To do this, temporarily reassemble the bowl with the hex head bolt. With the carburetor upright, dribble water into the fuel hose until it accepts no more - perhaps an ounce or two. There should be no leakage - the level of water in the hose should not change at all once it stops. If there is any leakage, there is still a problem with the inlet needle or seat - or the float is gas-logged.
- Install the large O-ring around the carburetor body. Use a small amount of engine oil to aid in assuring a good seal.
- Place the bowl over this assembly making sure that it does not pinch the O-ring. Orient it so that the deep part is almost opposite the float hinge (it should actually point directly away from the engine when the carburetor is mounted.)
-
Install the hex head bowl bolt and fiber washer. Tighten securely (one Tecumseh service manual lists 50 inch-pounds, but others have no recommended torque for this bolt). CAUTION: I've heard of people breaking the bolt by either attempting to loosen it the wrong way or overtightening upon reassembly to stop leaks. If gas leaks out in the area of the bolt head, the fiber washer may be missing or damaged. For testing at least, a non-hardening gasoline resistant sealer like Form-A-Gasket B(tm) can be used.