Simplicity 6216 Carb Help

Hi all, I just bought a 1981 6216 with a 16hp briggs. The carb was filled with some kind of white dried stuff. I soaked everything in vinegar cleaned with scrub brushes and passed wire ties through all the ports. Finished with sprays of carb cleaner to verify everything clear. I tested the float and it is functional and not leaking. I replaced the needle and seat and adjusted the float to level. I have fuel leaking into my crankcase still. I keep reading that the problem has to be the float, needle, or seat. I attempted to pull the old seat with the 1/4 tap and bolt method and failed. I ended up carefully drilling the old seat out. I know I hit some aluminum but not much, the new seat fit very snugly. So snugly that I slightly damaged the upper rim (didn't have the right tool either). I believe this is not the sealing part of the seat and a very slight ream on top edge now allows the needle to slide freely in the seat. I'm guessing I messed up and will need a new carb but can't find the part number. Let me know if you guys think I can save it. Also another potential problem, I suppose I ordered the wrong carb kit, everything fit and lined up perfectly except the fuel pump valve springs were too small. I ordered another fuel pump kit and replaced those. Is it possible the seat and needle are wrong but still fit? I still don't see how so much fuel could be getting by so quickly. Thanks guys

Since you didn't tell us which Briggs engine you are working on, I am going to take a guess and say that mower has a 2 cylinder opposed
engine on it:

If that is the case:

Since you said you had some problems with the fuel pump, Is there any chance you had to punch new holes in the pump diaphragms? Say they
were for a 4 screw carburetor and you have a 3-screw?

My guess your fuel leakage problem is in the fuel pump. fuel is leaking down the pulse hose into the crankcase.

You could also have a porous spot in the carburetor body, between the bowl and the air horn all those carburetors are getting pretty old
now.

I guess it could be the seat, since you said you had to drill the old one out. That's probably a no-no, any gap between the seat and the body will be a path for gas to bypass the needle.

If you ever change another one, pull it straight out, a 1/4" self tapping screw does't cost all that much, and push the new seat straight in. If you twist the old one coming out you may put a spiral groove like a thread in the body and that would be another path gas could bypass the needle. The idea is the new seat will form itself to the same surface the old seat left coming out and seal perfetly all around.

Thanks for the responses, TRK, you were on it. When I assembled the fuel pump I didn't notice that one of the gaskets was not the right shape and pressed against the diaphragm. I pulled it apart and since I didnt have the correct gasket, just deleted it for now. Works like a charm. The carb leaks no fuel whatsoever, the engine fire right up and runs great and reveals the next problem.... the frozen variator which is not allowing the tractor to drive at all. Joys...