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Having had the opportunity to examine a pair of carburetors side-by-side, the first from my late-model A4 and the second a fresh replacement from Moyer, they are not exactly identical.
Both are Zenith Series 68, model numbers 13355K and 288482 (both numbers somehow apply to the model).
However, the OLD one has the two tiny idle holes spaced one above the other in the throat of the carb. When throttled completely down, the throttle plate covers one but not the other.
The NEW one has the idle holes placed next to each other. When throttled completely down, the throttle plate covers both.
Does this difference affect the way the mix or idle of the carb should be adjusted?
Also, of perhaps less significance, the OLD one has a bolt in the very bottom of the float chamber that the NEW one doesn't have. Doesn't that make it harder to drain the new carb? There is another bolt in both, which I presume is another drain plug, is perpendicular to this and might not completely drain the chamber.
The old carb also has only four screws attaching the top and the bottom of the carb, whereas the new one has five. I remember reading someplace that this was a design improvement, although it's an obvious one -- the old one looks like it was designed and cast to have five but the fifth just wasn't drilled or tapped.
Both are Zenith Series 68, model numbers 13355K and 288482 (both numbers somehow apply to the model).
However, the OLD one has the two tiny idle holes spaced one above the other in the throat of the carb. When throttled completely down, the throttle plate covers one but not the other.
The NEW one has the idle holes placed next to each other. When throttled completely down, the throttle plate covers both.
Does this difference affect the way the mix or idle of the carb should be adjusted?
Also, of perhaps less significance, the OLD one has a bolt in the very bottom of the float chamber that the NEW one doesn't have. Doesn't that make it harder to drain the new carb? There is another bolt in both, which I presume is another drain plug, is perpendicular to this and might not completely drain the chamber.
The old carb also has only four screws attaching the top and the bottom of the carb, whereas the new one has five. I remember reading someplace that this was a design improvement, although it's an obvious one -- the old one looks like it was designed and cast to have five but the fifth just wasn't drilled or tapped.