Carter made replacement YF carbs for Chevrolet the smaller Chevy 6's (up to 235). Would suggest not using these on the 261.
Foorrdd used the YF on the 300 CID 6. Would suggest hitting the boneyards, and acquiring one of these from a late 60's or early 70's (the earlier, the better, as less smog calibration) Foorrdd truck for use on the 261. Should be readily available and cheap. Foorrdd sold lots of 300's. I take no responsibility for your speeding tickets. :p
Josiah, not much I like about the B, but it isn't fair to blame fuel valve (needle and seat) failure on the carb. A few years ago, the major manufacturer of repair kits started eliminated the "staking" on the fuel seat to save a few pennies. Next time you change the fuel valve, try the following:
Assemble a chuck of 2x4 lumber about 4 inches long, a drift punch slightly smaller than the ID of the fuel valve seat (the plunger portion, not the orifice), a ball peen hammer, and the used steel check ball that you are replacing in the carburetor. Place the thread of the seat on the 2x4, place the ball inside the plunger area on the orifice seat, place the drift punch on top of the ball, and whack (highly technical carburetor term - whack
) the punch with a hammer. Hit it one time only. This will form a tapered seat for the needle, providing better sealing and longevity.
