Rochester 2G, 2GC Carburetor

Please keep in mind that all technical information given assumes our parts are being used. Parts purchased from other sources may not install, or work in a like manner.

How to Find The Carburetor Number?

The older Rochester 2G carburetors had a small triangular tag attached to the top of the carburetor. Starting in 1968 the 2G carburetor had the number stamped on the side of the float bowl.

Rochester 2GC Carburetor

Free Rochester 2GC Carburetor Manuals

Rochester 2G, 2GC Carburetor Manual

Application Carburetor Number
1955-56
Chevrolet
7005810, 7006825, 7008004, 7008005, 7008388, 7008387
1956
Oldsmobile
7007223, 7008800
1956-58
Chevrolet Truck
7008393, 7008394, 7010717, 7012233
1957
Chevrolet Truck
7010717, 7008394
1957-58
Chevrolet
7010647, 7011131, 7010648, 7011224, 7010719, 7011149,
7012133, 7012451, 7012452, 7013652
1958-59
Chevrolet Truck
7012035, 7012047, 7012453, 7012455, 7013011, 7013011
1957
Chevrolet Truck
7010649, 7010718, 7010716
1964
Buick Adjustments
7024046, 7024047
1964 Chevy II, Chevelle 7024101, 7024106, 7024108, 7024110, 7024112
1963-64
Pontiac 389
7023063, 7023064
1963-64
Pontiac
7023060, 7023061, 7023062, 7023071, 7024062
1963 Pontiac 421″ Tri Power 7023078 Front, 7023079 Rear
7023162, 7023161 Center
1963
Buick
7023041, 7023042, 7023043, 7023145, 7023146
1962
Buick
7020046, 7020047, 7020048, 7020049, 7020146, 7020147,
7023048, 7023049
1957-58
Chevrolet 283″
7010647, 7011131, 7010648, 7011224, 7010719, 7011149,
7012133, 7012451, 7012500, 7012452
Checker
Motors
7023086, 7023096
Checker
Motors
7024183, 7024186

Marine

Application Carburetor
Number
Crusader 7015087, 7015088, 7015089, 7015097, 7015098, 7023080
Kiekhaefer
Adjustments
7020993

Hot Idle Compensator

Some Rochester 2g carburetors had a hot idle compensator attached to the middle of the venturi. When heated up, the bimetal bends up, exposing a vent hole and allowing more air into the intake. This compensated for an overheating condition on vehicle at idle, especially air conditioned cars. Below is a picture of what the assembly will look like.

Hot Air Compensator

2G Power Piston

Be careful when removing the power piston. The stem can break off easily and these are not longer being produced.  Push down on the stem and spring with your finger, then let it snap back. Do this over and over until the piston comes out. A frozen stem is another problem all together. Try spraying silicon spray lubricant into the vent hole.

Three Basic Types

2G – Manual Choke

2GC – Automatic Choke

2GV – Divorced Choke (choke thermostat is mounted in the intake
manifold)

Rochester 2G, 2GV Carburetor Catalog

Rochester
2G Jets
– includes the original jet sizes we currently have listed.

Watch a video about rebuilding this carburetor.

Tri-Power Setup

Testing Your Accelerator Pump Circuit

50 thoughts on “Rochester 2G, 2GC Carburetor

  1. Hi Mike. I ordered a 2g kit from you last month. In your video your make a correction to what sized ball goes in what hole. Can you confirm where the smaller ball goes? Main discharge or accel pump.
    Sorry for the confusion. Thanks Pat MacDonald

    • The smaller ball and sometimes made of aluminum goes into the accelerator pump well. Keep in mind that not all 2g carbs use a check ball in the pump well. A lighter ball is used because the well fills from gravity and the ball needs to be light enough to lift up.

      That leaves the bigger ball and stainless steel, which goes into the main discharge, followed by the spring, then the T.

  2. Thanks Mike. Got it fixed last night. My kit has two large, one small. Large were both SS and Alum. I used the SS.

    One more question if I may. The high speed jet (brass valve at bottom of plunger thing) the kit did not have a gasket that would fit that valve. I looked through my old gaskets and did not find one there either. Could it be a gasket for that valve is not needed? You mention in your video to be sure to use one and the instructions call for one, but I simply don’t have one.

    Any harm is not using one? The two jets don’t have one and they are brass to alum too.

    Thanks in advance for your help
    Pat Mac

  3. I can not find one in the kit. Looked all over. If you have one that would put me back on track. Thanks so much.

  4. thanks mike haven’t had to rebuild one of these in fifteen years. was debating buying a new one. 250.00 is what they wanted. rebuild kit 15.00. your video’s were very helpful thanks again mike

  5. HI, Mike
    I watched your 2 jet videos and they are great. I just bought a 72 cutlass with original 350 rocket and 2 jet. It runs great but has a heat soak flood condition. If you park it hot and come back out, you need to crank the heck out if it. I took the breather off and I can see fuel seeping out between the air horn and main body area sort of around the pump discharge thing- so I dont think the fuel bowl is leaking out the bottom like a quad. It looks like the carb has just been rebuilt. I checked the float level and it’s ok, lowered it anyway and still does it. Any tips, thank you
    Chuck

    • There is a good chance the gas is boiling out of the carburetor. Gas these days have a lower boiling point and when the engine gets hot and you turn it off, the gas immediately boils out of the carburetor. You then have to crank until the bowl fills up again.

  6. Hi Mike. Were you able to find a high speed jet gasket? Just checking b/c if not I’ll have to find one.

    Thanks
    Pat Mac

    Order # 5821

  7. In your video you state and placed the larger check ball goes in the accelerator pump, you stated in the comments the smaller aluminum ball goes in the accl pump. I belive your right in the comments and was just wanting to comfirm with you wich one is correct before I rebuilt my 2bbl. Thanks for the help and vids

  8. How can I tell if my carb requires the small ball into the accelerator pump hole or not? I’m not sure if any ball came out when I disassembled the carb. My carb tag is 7020993 (a Rochester 2 bbl 2GC for marine application)

    • The idea behind the checkball is that when you push down on the accelerator pump, the fuel moves to the main discharge and not back to where it came from, the float bowl. Carburetors that use a checkball will usually have a hole in the bottom of the pump well for the check ball, then another hole somewhere on the side close to the bottom of the well wall. When there is only one hole, then it has to be the delivery route to the main discharge and would not use a checkball.

    • I can’t answer this because the setting is different for every application. The specs are always printed on the instruction sheets that come with our carburetor kits. Try going to the 2GC section on this web site and see if there is a spec sheet there. If not then when I get the time I will post the instruction sheets on this site.

  9. Great Videos!!

    Turned my main body upside down and three check balls fell out. You only showed two going back in your rebuild. Only two came in my rebuild kit. Why do I have three?
    Thanks for your help. Very nice website.

    • Unless this is a late model 2G that I’m not familiar with, then there will only be two check balls. The smaller check ball goes in the accelerator pump and the bigger check ball in the main discharge tube.

  10. Hello. I have a chevy pickup C20 1971 with 350 original motor.. with a rochester 2GV carburetor on it. with nr 7008597 . I give this information because i can,t find this number on the site by the repair kits. probably should I place this information elsewhere.
    Regards G.Smit Netherlands

    • I’m sorry, but your number ins’t a valid carburetor number. The 2G had a tag attached to the top of the carburetor. When that is missing you have to take the carburetor apart and then compare the parts to each kit picture until you get a match.

  11. just a question about the trottle body.
    There are two air ducts on the back site of the boddy and comming out above the valve…..
    What is the purpose of these holes ????

    • Sorry, off hand I don’t know. I’m sure both are vacuum. I haven’t installed a carburetor on a vehicle for over 25 years, so I’m afraid I’m now much help of where the vacuum lines might go.

  12. I have a rochester 2G that I rebuilt the engine runs good but when it warms up it will only run for 3 sec then dies.I to use full chock to get it started and dies.I have try ed to adjust the idle mix. but I have had no look.

    • There are a lot of things that could be the problem, but you probably have a vacuum leak somewhere, or just aren’t getting enough fuel. There are several different flange gaskets for the 2G. Be sure your gasket isn’t leaving a gap somewhere. You can also squirt carburetor cleaner around the base. If the engine speeds up, then you found the problem. Also be sure you have the correct gasket between the throttle body and the float bowl. There are a ton of different gaskets for this also and easy to install the wrong one.

      Aside from that you should home in on where the gas fills the fuel bowl, float level, make sure the float isn’t binding, or rubbing and check the needle and seat. Take the top off turn it upside down. Blow in the inlet hole. You should not get any air through. Pick up the float a bit and blow again. This time air should go through.

  13. I HAVE A ROCHESTER 2 JET # 7036112 IN MY 65 CHEVY TRUCK I THINK THE CARB IS A 1966 OFF OF A CHEVY IPALA I HAVE ATTEMPTED TO REBUILD THE CARB IT IDLES GREAT BUT WHEN I TRY TO DRIVE AS SOON AS I HIT HIGH GEAR IT STARVES FOR GAS I REPLACED THE FUEL PUMP AS PART OF FUEL SYSTEM CLEAN OUT AFTER A 5 YEAR SIT I NOTCE THAT AFTER IT STALLS THERES NO FUEL PUMPING THROUGH CARB EVEN THOUGH THERES FUEL IN THE BOWL I WOULD BE VRY HELPFIUL FOR ANY HELP YOU COULD GIVE ALSO I NEED A CHOKE ROD THAT GOES FROM THE FAST IDLE CAM TO THE CHOKE SHAFT THANKS AGAIN ROGER

  14. Mike, thanks for the great info. I disassembled my Rochester 2GV and found that there was only one insert in the main well. The well is where the venturi cluster tubes sit. The parts breakdown show two of the inserts being used. Trying to locate another tube has prompted people to say to not worry about it and that the carb does not need them and to run without them. Mike, help ! I am a diesel guy and do not know who to believe. What should I do about the two main well inserts ?
    Thank you

    • I doubt the carburetor companies spent money to have parts put in a carburetor that weren’t really needed. Find a used carburetor to use as a donor and get your carburetor to original condition.

  15. Hi Mike,
    I rebuilt my 2 go with your carb kit.Car runs well now.Just wondering if a checkball goes under my accel pump or not as it didn’t have one when I took it apart.And it also didn’t have a pump return spring either.Are these needed?Thought I would ask before having to pull it apart again.Car does have a cold start problem.
    Any help would be appreciated.
    Regards
    Troy.

    • The 2G carburetor doesn’t always have a checkball in the bottom of the accelerator pump well. When a checkball is required, you will see 2 holes in the well. All of these 2 barrel carburetors have at least one hole for sending fuel to the main discharge where it provides fuel to the venturi. Some will have a 2nd hole which is used for fuel intake from the float bowl. A checkball is required on these. The checkball restricts the flow of fuel back to the float bowl when the accelerator pump is being pressed down.

      Be sure to use the smaller checkball in the accelerator pump well. The larger checkball is placed in the main discharge tube.

      Hope this helps

  16. Hi Mike,
    I have a 67 Jeep CJ 225 Dauntless V6 that has the 2G carb mounted. I’m planning on doing a rebuilt but as usual, no tag or stamp number on the carb. I’ve narrowed it to K6132 just because the air horn gasket is different compared to what’s given by application or vehicle. Question: Inside the well where the pump plunger goes is a check ball down in the bottom. Does that need to come out when rebuilt?

    Thanks,
    George

    • Yes, the check ball needs to be removed so that the passage can be cleaned and a new check ball put in in it’s place. The old check ball should fall out when you turn the carburetor over. If not, then someone may have put the large check ball where the small one should be. In this case try to removing it by blowing air in the main discharge, cleaning, tapping on the carburetor so that it dislodges and when all that fails:

      Drill a small hole in the bottom of the float bowl opposite where the check ball hole is. Poke wire through the hole in order to dislodge the check ball. They usually come out without too much trouble. When done seal the hole with a small amount of JB Weld. Be careful not to get any JB into the passage way.

      When you install the new smaller check ball seat it by tapping it in place a few times. Be gentle so that you don’t get it stuck. Also use a brass drift punch.

      • Thanks Mike! I ended up drilling from underneath the bowl. It was stuck in there pretty good. What surprised me was when comparing to the other check ball it’s the same size. Who ever rebuilt it last must of made a mistake. Thanks anyway!

        George

          • Mike thanks for that article. Question? In order for me to do the accelerator pump test I would need the smaller ball check, Right? If so then I need to order the rebuilt kit that comes with it. If the test fails would I be able to replace the fuel bowl or buy a another used 2G carb?

            George

          • The check ball does come in the carburetor kit. Finding a bowl would be difficult, so a used carburetor would be in order, however don’t give up too easily. Chances are you can seat the ball.

  17. No, I’m not giving up that easy. I’ve rebuilt a number Quad jet’s in the past but first for 2G. I’m going to order the kit along with a new float and take a chance hopefully the smaller ball will seat well.
    Thanks for taking the time with this one Mike. I’ve passed info to other guys who deal with carbs and they themselves are very impressed with the amount of info you have. Keep up the good work!

    George

  18. This is my first time on this website. I want to know how to convert a Rochester 2gc carburetor to an end carb on a tri power setup for a chevy 350 smallblock.. Is there a book, or an article on this that I coulb purchase?Thanks for any info.
    Thanks, Bill

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