Also known as the 4 Jet carburetor.

Where to find the carburetor number:


Rochester 4 Jet Parts

Please do not distribute the manuals listed. Instead we would appreciate a link to this page. https://carburetor-parts.com/Rochester-4G-4GC_ep_349.html


Rochester 4G, 4GC Carburetor Manual

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.
ApplicationCarburetor Numbers
1956 Oldsmobile7009775
1956 Buick Change in Primary Jets7009200
1956-58 Chevrolet7008737, 7009846, 7012126, 7012128, 7011108
1956 Pontiac7010600
1962 Buick Adjustment Specifications7020040, 7020041
1962-65 Chevrolet V8 Truck w/Governor7020025, 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 Studebaker7025186
1963-64 Oldsmobile7023050, 7024154, 7024050
1965 Olds F-85 & Jetstar 887025054, 7025157, 7025158, 7025055
1965-67 Chevrolet V8 Truck 3277025125, 7036125, 7027125, 7037125



Rochester 4G Marine Carburetor
ApplicationCarburetor Numbers
Chris Craft Adjustments & Specifications7013071, 7015090
Kiekhaefer7020995, 7023183
Kiekhaefer7023180
Owens Adjustments & Specifications7023184



Rochester 4GC Jet Sizes

Buy your Rochester 4G, 4GC jets here. More Jet Sizes
Carburetor NumberPrimary JetSecondary Jet
70231805970
70231836986

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.

Spring Loaded Floats - Torsion Spring


Some of the 4 Jet carburetors had a spring mounted on the float pin and hooked to the float. This helps take the bounce out of the float on rough roads. This is a part that is not being produced so what do we do now?

It is probably OK to leave them off; I do, however, reinstall them when I find that they are present. In the Era of Ethanol, carburetors can't have enough help!
 
That said, I have seen many come into the shop without them which, upon research, I found to have been originally so equipped. Since I had none to install, I simply left them off an they ran as well as any 4G is ever going to run.


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.


Watch a video about the throttle body gasket and looking for vacuum leaks.


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.


Needle & Seat

The 4 Jet uses 2 sets of needle & seats. Some 4 jets have different size needle & seat for the primary & secondary. When this happens use the bigger needle & seat on the primary side.

Can't find what you need? Contact Us
TOP