Tech Article

Carburetor Year Identification

In reworking so-called matched pairs of carburetors, I have found more mismatches so atrocious that it can only leave one laughing. Below is a quick guide which can be used to very quickly identify what you have or might be shopping for.

1960 - Very obvious as this year has no choke valves, choke shafts, or provisions for either.

1961 - Easily identifiable. This is the only year that has external manual choke linkage. It has no choke vacuum brake diaphragm unit.

1962-63 - Has choke vacuum brake diaphragm unit, but no idle vent values.

1964 (early) - Has choke vacuum brake diaphragm unit, idle vent valve, but no power enrichment needle.

1964 (late) - Has choke brake vacuum diaphragm unit, idle vent valves, and includes power enrichment needles.

1964 (general) - The exact difference between early and late 1964 carburetors is easily identifiable. However, the exact date, model,or serial number for this change is at best difficult and should only be determined after closer examination of the carburetor as described in chapter 4, CORVAIR CARBURETORS by Red Jackson; published in 1980.

1965 - Has choke brake vacuum diaphragm unit, idle vent valves, and power enrichment needles. The differences between late 1964 and 1965 is best determined by examination of internal differences.

1966-69 - Has choke brake vacuum diaphragm unit, idle vent valves, power enrichment needles, and pollution control valves. Yes, 1966 was the year of the air pump for California cars and was followed closely by most states. This valve is easily identified by looking directly down into the body and bowl assembly and can easily be seen at the forward edge of the venturi portion of the casting. It should be noted that some 1965 forward control Corvairs also had a similar type valve which served basically the same purpose of increasing the air/fuel ratio or leaning the fuel mixture.

Early/Late Internal

I should specify what I mean as early versus late. This difference to me is generally to the body style; ie., the basic difference between 1964 and 1965 body styles. Corvair carburetors generally follow the same styling differences.

All venturi cluster assembly ports are evenly spaced between each other. Venturi cluster assembly ports are unevenly spaced. This redesign was based on research efforts resulting from sonic impulse consideration.
This notch coincides with the idle mixture adjusting screw. The design intent of the notch was to provide for a smooth fuel flow from the idle cavity to prevent fuel slugging which could cause an intermittent rough idle. Additionally, the notch would help maintain a smooth idle during icing conditions as ice will not be able to build up in this area causing rough idle and stalling.
FLOAT ASSEMBLY. Anyone know the difference?
The differences are quite revealing and provide an insight for the difference between the float drop and float level dimensional variances of early and late models.

Distilled from CORVAIR CARBURETORS by Red Jackson; published in 1980.
Transaxle Telegraph, Oct. 1996, Vol. 22, No. 10

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