EBay carb evaluation

[Bob McCarty]

This is an evaluation of the physical attributes of these inexpensive carbs. I have not mounted one on a Cub and tried to use it. Also, I'm not an M.E., so there may be places where deviations from OEM are irrelevant. It'll be a long post and will be one post for the top half and a second post for the bottom.
The top: the first thing I noticed was that the mating surfaces of the top and bottom halves were not machined. The top has a very thin bead that runs around the perimeter and screw holes of the top. The gasket is a thin "cardboard" similar to the original gaskets or the aftermarket ones. The halves fit close but not perfectly. The solder joint on the float was sloppy and a little heavy on the arm. The float drop measured okay, but the height was off by about 1/8". The throttle shaft was very loose which made me wonder if there was a shaft seal in place. In trying to remove the phillips head butterfly screws, I stripped both and had to grind them off. The butterfly is made out of aluminum and the two screws were actually torqued into the Al. It's stamped 14* and looks like it has the correct bevel. The throttle shaft is about .005" smaller than OEM and an OEM shaft will not fit. There was a "foam" seal that I could easily compress into a small bb with my fingers that probably did not provide much of a seal. The needle seat looks like the OEM. The needle has a viton (?) tip. The opposite end has a small spring loaded ball bearing. Unfortunately, the needle stuck about two thirds of the times that I inverted it. The idle tube is not threaded but a press fit. It did rotate and also pulled out fairly easily. The hole is larger than the OEM 4-48 thread and larger than a 5-40 thread. To use the correct idle tube, a helicoil would have to be placed. The orifice was smaller than the .021" it should be, but I had no way of measuring below .020". The gas inlet threads are correct. The inlet filter was inserted about 1/4" past the shoulder that it should rest on. Air adj. needle is similar to OEM. Manifold surface was flat and manifold studs were correctly threaded.

Next post: the bottom