Identification of Rochester Carbuertors for Cadillac

[John Washburn CLC 1067]

I have been trying to determine the identity of 6 Rochester 4 GC Carburetors for Cadillac. The first clue is the linkage connection, only Cadillac used the 3 screws connector for the accelerator linkage. All 6 of these carburetors are off some Cadillac car.
The problem is that without the tag it is, I believe, very hard to identify these carburetors. So I started with a 1956 Cadillac Rochester with the tag, which identifies it as a carburetor off a 1956 Cadillac. This particular carburetor has, in the air horn assembly, only two vent tubes (as does 1952 thru 1955). It also has the choke assembly mounted on the air horn assembly. I verified this in the Cadillac shop manual and that is what the pictures show also. Picture “56 Roch Vent Tubes and 56 Roch Choke” shows the parts described.
Next I started looking at the Cadillac shop manuals, 1957 up. I found for 1957 and 1958 the Rochester 4 GC still have only 2 air horn vent tubes, but the choke was now mounted on the float bowl assembly. See pictures “57 58 two vent tubes and 57 58 Choke”. I checked my friend’s stash of Rochester carburetors and found 3 that matched. One problem with this view is that the carburetor rebuild kits are different from 1957 and 1958.
I next looked at the 1959 Cadillac shop manual and found that starting in 1959 the Rochester carburetor used a 4 air horn vent tube configuration. See pictures “59 up four vent tubes and 59 up choke on float bowl”. When I checked the stash of carburetors I found 2 that fit the pictures.
I think I have identified the 1957 and 1958 Rochester 4 GC Carburetors. If I am incorrect please straighten me out. In the 1959 and 1960 Cadillac shop manual the pictures look like the other Rochester Carburetors I have, and they both use the same carburetor kit. In 1961 the air horn assembly changes and has four vertical pipes/vents, on the outside top, that are not present on 1959 or 1960. So I think this puzzle might be solved. Again, any insight or idea how to better identify these rascally Rochester carburetors would be appreciated?

I could only post two picture so will post the other four in aother emails.

John W

[John Washburn CLC 1067]

Next two pictures.

John W

[John Washburn CLC 1067]

Final two pictures.

John W.

[Otto Skorzeny]

Hi John,

Perhaps this website can help you. They have free online manuals for every Rochester carburetor made from 1932 to 1980.

New Age Metal                                       
http://www.newagemetal.com/

[John Washburn CLC 1067]

Otto,

I am crushed. You think I don't have these? But I do, and they are worthless for identification purposes.

John W.

[Otto Skorzeny]

I figured you probably did but one never knows.

[Bob Schuman]

This won't hepl identify your Rochester carbs, but raises a question in my mind.
The linked website lists a Rochester for Chevys back to 1932, but I thought the 1949 Olds V-8
was the first production car using a Rochester carb. Is my old brain getting that faulty?
Bob Schuman,CLC#254

[Jose Gomez]

John,

You are 110% correct that w/out the tag it would be difficult to identify the application for these 4GC carbs since they were shared across other GM models. There are a few key items that differentiate these one as you pointed out being the throttle body linkage. This would be the only identifier (w/no tag) if you are looking at same year 4GC (top view) from other GM models as the bowl and top plate were identical i.e. Olds, Pontiac.

Not sure if you have the following link from Walker Product, I know their kits include parts for all of these variances. http://www.walkerproducts.com/_pdf/rochester4barrel.pdf.

[Jose Gomez]

This won't hepl identify your Rochester carbs, but raises a question in my mind.
The linked website lists a Rochester for Chevys back to 1932, but I thought the 1949 Olds V-8
was the first production car using a Rochester carb. Is my old brain getting that faulty?
Bob Schuman,CLC#254

Bob,

Actually Chevrolet 1932-1950 w/manual tranny had the Rochester “B” type, and 1932-1950 w/auto choke had the Rochester “BC” type. The Olds 1949 w/Hydra-matic used the Rochester “AA” type.

[John Washburn CLC 1067]

Jose,

Actually my book shows the Rochester Model B - Manual Choke, 1932 to 1952.

John W.

[Jose Gomez]

Jose,

Actually my book shows the Rochester Model B - Manual Choke, 1932 to 1952.

John W.

John,

I have the Rochester Bulletin 9 B-10C dated November 1959 and it list the "BC" for the 1932-1950 Chevy 6-cyl w/automatic choke  Ooops a new mistery..! 

[John Washburn CLC 1067]

John,

I have the Rochester Bulletin 9 B-10C dated November 1959 and it list the "BC" for the 1932-1950 Chevy 6-cyl w/automatic choke  Ooops a new mistery..! 

Jose,

The one I have is 9C-300, February 1960. Then Bulletin 9C-300, 4-1-53 says the same.

Of course this is absolutely no help in my quest for information!

John W.

[John Washburn CLC 1067]

Jose,

What I forgot to add is that they both say 1932 to 1952.

John W

[Jose Gomez]

John,

Thanks for the 411..!

Good luck on your quest.