YFA 1BBL Carb Question
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Joined: Dec 2010
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From: Harrisburg, PA.
YFA 1BBL Carb Question
I know somebody on here has taken one of these YFA carbs apart. What I want to know is,,,,what is the number that is on the metering rod? The metering rod has a part# stamped on it. I think the only difference on the metering rods would be to compensate for altitudes.
The truck I just got has a new carb on it and I don't want to mess with it until I get another one from the JY. The local JY doesn't have one. I want to rebuild one and change the metering rod in to see what affect it has on my MPG. If I screw it up, I can always put the new one back on. I used to rebuild the Carter AFB's on my 409 and would change the metering rods on it at the strip. The YFA uses a different style rod but the concept of the carb looks to be basically the same as the AFB.
I'm old, jittery and don't see as well as I used to. That's the reason for saving the new carb I have on the truck now. I want to cover my behind in case I have a Senior Moment when rebuilding the other.
The truck I just got has a new carb on it and I don't want to mess with it until I get another one from the JY. The local JY doesn't have one. I want to rebuild one and change the metering rod in to see what affect it has on my MPG. If I screw it up, I can always put the new one back on. I used to rebuild the Carter AFB's on my 409 and would change the metering rods on it at the strip. The YFA uses a different style rod but the concept of the carb looks to be basically the same as the AFB.
I'm old, jittery and don't see as well as I used to. That's the reason for saving the new carb I have on the truck now. I want to cover my behind in case I have a Senior Moment when rebuilding the other.
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Joined: Nov 2004
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I've had my YFA apart a couple of times. I never looked for numbers on the metering rod, but it makes sense that Carter would have different rods for different applications. Changing the profile of the taper on the end of the rod would change how much it enrichens the mixture at any position of the rod.
Under cruising conditions, when manifold vacuum is high, the metering rod is going to be pulled all the way down into the main jet, so the profile of the taper is not going to come into play. The diameter of the non-tapered part of the rod would affect mixture still. If you have a micrometer or calipers, you could measure the diameter of the non-tapered section to see if there is any difference. A larger diameter is going to lean out the mixture a little, just like going to a smaller jet.
Under cruising conditions, when manifold vacuum is high, the metering rod is going to be pulled all the way down into the main jet, so the profile of the taper is not going to come into play. The diameter of the non-tapered part of the rod would affect mixture still. If you have a micrometer or calipers, you could measure the diameter of the non-tapered section to see if there is any difference. A larger diameter is going to lean out the mixture a little, just like going to a smaller jet.
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