stromberg needle and seat

[fcee]

Does any one know type and size of the male thread that screws into an fc carby ? am trying to locate a tee piece to use on twin carb fuel lines . thanks Steve .

[Errol62]

Yes. Harv.


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[Harv]

The Stromberg inlet threads (the ones that are made in alloy, part of the carb float bowl) are 7/16-24UNS. You cannot put a tee directly onto the float bowl. The brass fitting that normally screws in to it is the "seat" part of a needle-and-seat. It has a machined inner surface to allow the needle to seal... a tee fitting will not have this surface. The seat also has a small internal diameter (orifice) to restrict fuel flow into the carb.

The "other end" of the brass seat is where the fuel pipe normally bolts up. This would be an OK location for a tee. The thread size is 1/2-20UNF. Note however that the seat is not a simple UNF thread. It is an inverted SAE flare (45º double flare) to suit 5/16" pipe. Your tee would need to be have this (male) type of flare end on the leg that threads into the carb. You can probably buy them, but I can't say I've ever seen one in 45º flare.

Most people run a short length of 5/16" pipe out of the seat, with a 1/2-20 flare nut on both ends of the tube. One end screws into the seat, and the other end screws into a female inverted flare tee. Female tees are easier to purchase.

Cheers,
Harv

[my8thholden]

Steve  .You may find the fitting Harv is suggesting at IFS ( Industrial Fitting sales ) at Ingleburn ..I am pretty sure you can view their catalogue on line ..Fuel fittings sect ....They tend to refer to NON British threads as NPT which is American ( National Pipe Thread ),but not what fuel fittings are ,so just confirm the threads Harv advises and check the TPI . .I haven't dealt with them for years ,new catalogues may have addressed all problems ,but they are good people .cheers Vern ..

[fcee]

Thanks guys ,let me tell you what my idea was , to modify the brass seat removing the
nipple that extends past the male thread ,enlarging the hole slightly ,then simply screwing the fitting into a tee piece ,by doing this to the three legs of the tee I could then use normal fuel tube to all my connections ,just need to find that tee .