One of the most insidiously successful sales efforts is that of aftermarket suppliers of vintage carburetor rebuild kits. Way out of proportion to their real value, carb kits are thought by many to be not only a good thing, but necessary and indispensible. The truth is so far from this it is tragic. Carb kits contain parts that in the first place never need replacing and in the second are made so poorly (in attempts to cover say, seven different models, not one of which is properly fitted) that encouraging the tossing of the stock parts in favor of these bastard-bits is nothing less than criminal, inasmuch as the stock parts, which never wear out and are made right, are not, at this late a date, obtainable. This means they have to come out of a spare carb set. Can you say "expensive"? I can't begin to tell you the heartache first to myself, then to my client, when Keyster or K&L parts are discovered in a carburetor. It really is one of the saddest messages I ever have to deliver. It is assumed you understand Randall Washington's stupendous kits I do not group among the aftermarket genre, though they are of course technically that. They're in a different universe. I hate to even call them kits. They are so good, so high quality, I view them as ex-officio OEM. They don't contain things you don't need, or cheap soft rubber gaskets. Great stuff! For carburetors Randall does not support, there are very credible sources that pro carburetor rebuilders rely on. Seldom does one ever have to resort to the conventional, ubiquitous, but much-to-be-avoided kit.
As I say, I cannot say enough good things about Randall Washington's carburetor rebuild "kits.". Actually more seal, diaphragm and o-ring sets, they are simply the best there is. Because none of the aftermarket ones are up to his standards, he doesn't include float valves. But everything there is good stuff. Properly-sized Viton rubber o-rings, diaphragms, etc. In several of his kits Randall and I collaborated on the spec for the idle mixture screw o-ring. At first this part was the same size it is in many aftermarket kits, oversize in other words. Most kits have this o-ring oversize even today, with the result it tends to fold on installation, which if it happens will affect the idle, making it rough and uneven. This won't happen in Randall's kit. The size of the idle mixture o-ring was updated years ago and is now identical to stock. Randall also included the float bowl screws at my insistence. You can't go wrong with this 98-piece "kit." It's very very good.
Take a look at this K&L float needle, on the right. It won't seal, it fails a vacuum test. It's brand new, straight from the package. Keyster are the same. You can tell from looking at this part it isn't made right. See how the tip is ground off-center? K&L used to be a big name, quality stuff. Not any more. Junk.
On the left, another aftermarket float needle. It should not surprise anyone that I do not like aftermarket float valves.