1955 Rochester Carb

[D.Yaros]

A genuine OEM NOS Rochester Carburetor Products Primary Venturi Cluster Assembly for all models of the 1955 Cadillac w/ single 4GC Carburetor. This is the improved Venturi cluster which was developed and utilized on all regular production Rochester 4GC carburetors beginning in February of 1955. These carbs were identified by the addition of a tag marked 'XB' on the carburetor itself to denote the addition of the improved venturi cluster. The change was prompted by complaints about  poor performance and "stutter"/hesitation issues upon hard acceleration (especially between 20 and 40 MPH)  being received by Cadillac Service Departments across the country. Research would show that the standard earlier production venturi clusters utilized in the factory 4GC carburetors (carb #'s 7007970 and #7007971) utilized from 1952 to early 1955 would tend to cause the carbs to run too lean. This improved cluster reportedly corrected the problem and can be documented via a United Motor Service Bulletin dated 3-10-55.  This part, which carries GM/Rochester Products Part #7008766.


Is there any truth to the above?  Appreciate your input.

[Walter Youshock]

It's possible.  The "Cadillac Serviceman" bulletins or a carb bulletin should have that information.  I do know how troublesome the '57 Rochesters were.  There were modifications and improvements being made many years after the production year of the cars themselves. 

I would never rebuild a carb to the specs found in the Shop Manual.  Chances are, there were many altered specs through the usable (5-10 years) of the car. 

[D.Yaros]

Wonder if someone with access to the Serviceman can see what is said about the carb and venturi mods?

[Walter Youshock]

Not only would the '55 editions help but the '56 as well.  Many times, problems arose and were corrected one or two years after the build date of the car.

[D.Yaros]

According to the data, this problem was detected and attempted to be resolved by Feb. of 1955.