YF Check Weight
Carter YF & YFA Check Ball & Check Weight Placement
1st of all we should know what the check ball & check weight is for. When you press on the gas to accelerate, the engine needs an extra spurt of gas to get you accelerated until the cruise circuit can catch up. This is where the accelerator pump circuit comes in play. Pressing the accelerator causes the accelerator pump diaphragm to move up forcing a small amount of fuel out through the main discharge. The force of this fuel forces the check ball and check weight, or in some cases just the check weight up, allowing fuel to flow through the main discharge. When gas isn't being pushed out the discharge, the check ball closes off the fuel so that vacuum from the intake doesn't siphon fuel through the main discharge.
Some Carter YF carburetors have a check ball with a check weight on top of it.
Namely,
Carter YF Carburetor 1971-74 Ford
1971-74 Ford 200, 240
See # 24 & 25 in the illustration below. Notice that the check weight is rectangular shaped. This check weight is nothing more than a weight. It probably weighs less than 1 gram, but that's OK. Too heavy and the check ball would not lift off the hole.
Carter YF Carburetor Check BallOther YF & YFA's might have just a check weight, but this check weight is tapered on the end and this taper acts the same as a check ball does. See #26 in the illustration.
Carter YF Check WeightCheck weight w/o check ball. There are 3 different lengths depending on the carburetor. Most use this one captioned here. After placing in the main discharge you should have 1/16 - 1/8" free space for the check weight to lift off the seat. You can grind the check weight down to fit.
Carter YF check weight
Check weight w/check ball.
Make sure you have about 1/16" - 1/8" of free space for the check ball to lift up.
If you need more, simply grind down the check weight to fit.