does anyone have knowledge on the right size metering rod jet should be on a carter yf carb? its on my 46 chevy truck 216 6 cyl the carb has 864s on it is this an instance where you try different sizes untill you find the right one? maybe theres a tech manuel that specifies? rebuild kits DO NOT have this jet i guess cause every carb is different maybe match the meter rod? i know i need smaller cause im running rich but dont know what to get thanks for any wisdom on this
If you are running rich you need a larger metering rod. Before you change rods make sure the rod is mounted right on the holder & the vacuum diaphragm is good. Also check the float for gas leaking into it & the float level.
Last edited by Wrenchbender Ret.; 04/12/20173:31 AM.
They say money can't buy happiness. It can buy old Chevy trucks though. Same thing. 1972 Chevy c10 Cheyenne Super In the Gallery Forum
(1) With all due respect, you have probably either misread the number, or the fickle typing fingers typed the incorrect number. Probably should be 964s rather than 864s.
(2) The better rebuilding kits DO contain the jet.
(3) If I guessed correctly on the 964s, it is an aftermarket carb, so the only specification sheets are contained in the Carter Master Sales & Service manual, and yes, they are in this manual.
(4) 90 percent of the time, rich running is caused by defective ignition. Would suggest checking this second, after you check the compression (5 percent).
(5) If the compression and ignition are both good, you have not installed a powerful electric fuel pump (the YF likes about 3~4 psi)) and you have not installed a pertronix conversion in the distributor without also installing an alternator; then a good carburetor rebuild is in order.
(6) If the carburetor is built to stock specifications, and you are using ethanol fuel, you are far more likely to be lean than rich; HOWEVER, if you are running rich, then Wrenchbender's comment about the rod is spot on. With Carter's sophisticated metering rod technology, simply changing a jet (unless it is a very MINOR change) will guarantee that the metering will be off at at least one value of vacuum. The metering rod technology allows for the calibrations to be set at multiple values of vacuum; as the effective metering area is the area of the jet less the area OF THE PORTION OF THE ROD CURRENTLY IN THE JET. But this technology also means that a recalibration should be done with a different rod. And if the diaphragm is bad, fuel will syphon through the diaphragm and cause a rich condition.
Suggestion: do some more testing. If you do have a 964s carb, it is one of the finest (opinion) carbs you can put on that engine. If after testing, you are sure the issue is the carb; and need either help or parts, call me (573) 392-7378 (9-4 Mon-Tues central time).
And one final suggestion: if you have installed a pertronix conversion, I would suggest replacing with the original points/condensor FOR TESTING just to see what happens. The two most common "carburetor" issues we see are pertronix conversions and ethanol fuel. I won't try to talk you out of using it, but it certainly can be a problem!
One late thought: again, assuming I guessed correctly on the 964s,the orifice for the fuel valve should be 0.081 inch. Most of the cheap kits have an orifice of 0.101 (for the Ford 300 CID six). Too large a fuel orifice will cause the fuel level in the bowl to be too high, thus causing a rich condition; but this is not the fault of the carburetor.
Jon.
Good carburetion is fuelish hot air The most expensive carburetor is the wrong one you attempt to modify. If you truly believe "one size fits all," try walking a mile in your spouse's shoes! The Carburetor Shop
thanks for all the good info the fuel valve orifice you are refering to is what the metering rod is riding in? in the bottom of the rod?is the number stamped on the brass?
Mine is, 099. That is 0.099". Still very available in steps of 2 or 3 thousandths up thru 0.119".
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
One thing I'll add...some of the YF models I've seen have suffered warped diaphragm bonnets. What happened here was some person over-tightened the 4 screws too tight and that caused the 4 ends to compress. This leaves the center of the bonnet higher...but it gets worse. In some kits you'll find a fiber gasket made to correct this situation. It actually allows the ends to compress more and increases the warping. If the center section of the bonnet does not seal against the float bowl recess at all points the ever present vacuum in there will suck raw gas right into the manifold.
Wow! Rub eyes. This is a 5 year old posting. Timotheus, did you call Jon at the above number? We try to help people and answers their questions but we depend on getting feedback (responses) in return.
"Fuel valve orifice" are words that can also be called needle valve. This part has a connection to the float which controls the level of fuel in the bowl.
The metering rod goes inside the metering rod jet. The rod and the jet are stamped with numbers.
Let us know if you need the information/training booklet that Carter Carburetor published for the YF model.
"Adding CFM to a truck will only help at engine speeds you don't want to use." "I found there was nothing to gain beyond 400 CFM."
