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Hi All, what is the tap size for the emulsion tube on a B&S Flo Jet carb.
Thanks
Geo??

Either 1/4-32 or 5/16-32

Right! ,5/16X 32 NC, UNC UNFE , what is all this about, it appears it’s not a standard tap, I have been trying to determine what the difference is, it may be cheaper to buy a new carb.
OMG!

5/16-32 is UNEF = Unified National Extra Fine which is a standard tap in this pitch. It is also in my carburetor tool kit. When compare to the ground down nozzle for the two piece flo jet it appears to be right diameter. There is also a 9/32-32 but is a special thread size. Try to put 9/32 drill in the hole for the nozzle. IF it fits then it is the 5/16-32 tap. The 9/32 will take a 1/4 drill bit but not the 9/32 bit.

So if the 9/32 fits use a 5/16 X32 tap, UNEF,UNF or which?
Geo ??

Don't let the thread abbr get you confuse. All you really need to know the diameter and number of threads per inch; unless, you want to go to British threading.

SAE thread designations:
UNEF is the unified normal extra fine designation. Which is in the case 5/16 is the 32 TPI
UNF is the unified normal fine designation. Which is in the case of 5/16 is the 24 TPI
UNC is the unified normal coarse designation. Which is the case of 5/18 is the 18 TPI
UNS is the unified normal special designation Of course those taps are fairly expensive with them being over 4X the normal tap prices. 5/16 versions of these comes in 20, 27, 28, and 40 TPI.

With TPI being threads per inch.

Hi, would this tap work?

It might work, but I’m thinking you are probably going to need a plug or bottoming tap. That tap is a taper tap and may not cut threads as deep as needed.

OK, Thanks

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