Rochester 4G, 4GC Carburetor

 

Also known as the 4 Jet carburetor.

Rochester 4G, 4GC Carburetor Manual

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Free Rochester 4G, 4GC parts catalogs.

One way to help identify your carburetor would be to match a part number from your carburetor (there is usually one somewhere), with a part in the catalog. Once you have done that, you have your carburetor number.

Application Carburetor Numbers
1956 Oldsmobile 7009775
1956 Buick Change in Primary Jets 7009200
1956-58 Chevrolet 7008737, 7009846, 7012126, 7012128, 7011108
1956 Pontiac 7010600
1962 Buick Adjustment Specifications 7020040, 7020041
1962-65 Chevrolet V8 Truck w/Governor 7020025, 7020029
1963 Buick Special V8 215″ 7023044, 7023045
1963-65 Buick V8 401″ 7023040, 7023143, 7024040, 7025040,7025140
1964 Buick V8 300″ 7024044, 7024045
1965 Studebaker 7025186
1963-64 Oldsmobile 7023050, 7024154, 7024050
1965 Olds F-85 & Jetstar 88 7025054, 7025157, 7025158, 7025055
1965-67 Chevrolet V8 Truck 327 7025125, 7036125, 7027125, 7037125

Rochester 4G Marine Carburetor

Application Carburetor Numbers
Chris Craft Adjustments & Specifications 7013071, 7015090
Kiekhaefer 7020995, 7023183
Kiekhaefer 7023180
Owens Adjustments & Specifications 7023184

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Rochester 4GC Jet Sizes

Buy your Rochester 4G, 4GC jets here.
More Jet Sizes

Carburetor Number Primary Jet Secondary Jet
7023180 59 70
7023183 69 86

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1956 Buick – Change in Primary Main Metering Jets.
4GC, carburetor number: 7009200
A change was made while being produced to this carburetor. The primary main jets were changed from .056 to .060. A “D” stamped on the carburetor tag signifies that this change was made.

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Watch a video about the accelerator pump vent.

Watch a video about rebuilding the Rochester 4 Jet.



Watch a video about the Rochester 4GC integral choke.

Watch a video about the Rochester 4G jets.

 

Question:
Can one of the emulsion tubes be missing from the venturi?

Answer:
Sometimes those fall out.  I would simply try to find another 4G and pirate an emulsion tube from its booster cluster.  Compare the size/number/placement of holes with the remaining tube and modify as necessary.  Install new tube to same depth as old one with a light coating of Permatex Anaerobic Gasket Maker on the press-fit surface.

Question:

When I took apart my 4gc (7024121) there was no aluminum check ball in the pump intake cavity. Does it take the large one or the small one that is in my kit?

Answer:

1st you have to be sure you need a check ball. Carburetors that use a check ball in the accelerator pump well will have two holes at the bottom. One for intake and the other for out flow. When there is only one hole, then no check ball is needed since the hole is the out flow and if you placed a check ball there, the flow to the main discharge would be cut off. When you have two holes, then use the smaller of the check balls and these are often made of aluminum instead of stainless steel. Aluminum is used to make the check ball lighter since only the weight of the fuel lifts the check ball off of the hole to allow fuel to enter.

4 thoughts on “Rochester 4G, 4GC Carburetor

  1. Hello Mike.

    Can you tell me where I can find a Carter W1 Carb Governor??. I have a 1946 Chevy 1-1/2 Ton, Flatbed Truck.
    What is the part number, What does it look like, And where can I find one??.

    Thank you for your time..

  2. I need help to identify a carter carb on a 1960 biscayne,the engine decodes back to 1958 283,it looks like a regular carter carb but has a wierd attachment on th passenger side ,a counterbalance weight and has a additional butterfly on the secondary any clues?

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