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


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.  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, or apply heat to the outside of the piston well.

Three Basic Types

2G – Manual Choke

2GC – Automatic Choke

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

Rochester 2G, 2GV Carburetor Catalog

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

Tri-Power Setup

Testing Your Accelerator Pump Circuit

88 thoughts on “Rochester 2G, 2GC Carburetor

  1. Hey Mike, I’ve got a Rochester carb (#17057110) on my 1985 Chevy 305 (4wd Silverado) with headers. I’ve set the timing and the fuel mix screws (final setting 3 turns each from seated) according to the manual. All good. This is the first time this carburetor has been linked to these headers and I’ve heard with headers I should probably re-jet the carb to avoid running too lean and burning valves. Drove about 20 miles and checked plugs, medium tan color. Bought a rebuild kit today. Any advice on how to proceed on choosing proper jets? Thanks again. Phil

  2. I have a Rochester r2-2gc carburetor on a Chevy 305 that I just dropped in my 1985 Silverado. Carb was flooding and I looked at your site for help. Was able to figure out that I had installed a short bolt to seal that threaded hole where you install a bolt to hold the fuel pump piston back during install. That dumb move raised the fuel pressure and caused flooding. I removed the blockage half hour after looking at your site and problem solved. Pass it along if it helps someone. Thanks a lot for your help! I had already bought rebuild kit, tech manual and priced another carb ($200). Phil

  3. Hey Mike…
    Thanks for taking the time to help us all out… valuable info.. I have a rebuilt 2G… can’t get it to squirt .. new ball, pump swapped nozzle fitting with a spare that worked.. tried two pumps.. blew out every orifice I could find… think it’s plugged in the body somewhere..? …. first three carbs tested perfect but the last one that’s failing did have a ball lightly stuck in the seat but I was able to remove it without damage.. carb was missing the base to body gasket so I also grabbed one off the parts unit just to test. not sure what to test next..? Tx again Dave – Toronto

  4. Hi, sorry for my english but i have a impala v8 283 1964 and i need to know if you have a new/rebuilt carburator for sale? idont know if it uses 2g 2gv!

  5. Hey there Mike, My 2 bbl Rochester has a broken base bolt, 1 of the 4 that bolts to the manifold. Will it leak air? Can I use a sealer on the empty corner? Or is it drill and tap time. Thanks for your site, a good read. Sincerely, Fritz

      • Drilled it out and tapped it, and found the culprit that I suspected when my fuel flow stopped up…that Flintstone brass, stone age inner filter. Tossed it as far as I could, wher it belongs amongst my gravel. All is well now.

  6. Hi,

    I am trying to locate a Rochester 2G side inlet with manual choke air horn. Do you have them in stock or know anyone that might have it? On my original air horn the 1″ threads are stripped on the side inlet. The threads on the 1″ nut is okay. Some mechanic messed up the air horn side inlet threads before I acquired the truck from my grandfather.

    Thanks in advance! Layne

  7. Hi Mike,

    I am new to this, just heads up!!! I have a Tri power Setup on a small block 350 in a 1959 Chevy Apache truck. I know it is a Rochester 2 jet, but I cannot find any numbers. I am having problems with the card next to the fire wall. It is floating, I think I should do a rebuild, so I want to get one of your kits. Help please…thanks what could cause it to flood the float sticking?

    • To determine the correct carburetor kit we would need the carburetor number. That carburetor came with a small tag attached to the top of the carburetor which included the carburetor number. When that is gone, the only way to be sure of the correct kit is to take the carburetor apart and compare all of the parts with what we have in our photos.

      When comparing start, with the carburetor kit that includes your car in the application list with the chance it is the original.

      Keep in mind that car manufactures often used multiple different carburetors on the assembly line.

      Carburetor kits care about the carburetor, not what the carburetor is mounted on.

      Compare the measurement of the accelerator pump. That is often what is different between the kits.

      Float level.
      Bad float. For brass floats, heat some water and immerse the float. Any bubbles indicate a leak and the float should be replaced. Nitrophyl floats should be replaced. The only test is to weight them.
      Fuel pump pressure.
      Power valve is not seating, allowing fuel past it when in non power mode.
      Fuel is leaking past needle & seat. Be sure you cleaned the old gasket material off completely.
      Main discharge check ball is not seating. Hold the ball down with a brass drift punch. Put fluid (like mineral spirits) in the pump well. Press the accelerator pump down. You should feel some pressure. If the ball is not seating, fluid will be siphoned at idle. You an seat the ball by hitting it gently with brass drift punch and hammer.
      Run thin wire down all small passages, especially the venturi.
      Seat was damaged when installing. Too much pressure on the seat when adjusting the float is a common problem. Inspect the viton tip closely for any marks.

  8. hey mike, i have a 67 cutlass 330 stock 2 gc rochester and im having issues where the gas comes out of the carb gaskets. doesnt leak if your using the throttle, and most of the time no leaks when its running. seems like once i shut it off it startings dripping (quickly) out of the throttle lever/hinge and on the other side near the vacuum choke assembly. car ran fine up until that point, new fuel filters, lines and the tank cleaned out previous to this. checked the float and put new gaskets and reassembled but still having issues. will happen even when the cars only a little warm and the carb still feels cool to the touch, so maybe not heat soak?? any suggestions? -thanks- alex

  9. how would my 2bbl carb react if i put a check ball in the pump well and it did not need one ? i’m pretty sure there were two holes in it and i placed it in the slotted side (if memory serves me correctly)

  10. Hi Mike, it appears you have an excellent site here with much information.

    I have pulled a Rochester 2…x ?
    carburetor from a 1966 Oldsmobile Ninety Eight with a 425 CID.
    The number tag was pulled from it. Must have happened from a prior rebuild so I’m unable to ID by number.
    This unit has a strange idle vent valve arrangement


    My best assessment is it is flavor of a 2GC model, is there a way to determine a number and/or are you able to direct me to a rebuild kit based on those details?

    Best Regards,

  11. i have an old volvo penta 150b engine in my boat….it has a rochester 2gc carb but there is no id number on it ??? im having problems with power when i throttle up….seems like lack of fuel??? ive noticed when i throttle up little or no petrol comes out into the carb…its seems like the jets are blocked ??? or maybe needs refurbishing ?? can you advise me on which carb kit i need and can you supply for me ?? im in the united kingdom (england),,,,,,,hope to here from you ……..pierre

  12. You don’t recommend accelerator pumps on tri power end carbs. I planned on using them for dumpers only and had heard that having accelerators can easily cause a fat condition. So, what you are saying now makes sense to me.

    • Just keep in mind there that there are more knowledgeable people out there on the tri-power. Not something I worked with much through the years.

  13. I rebuilt my Carb and I reassembled as I took it apart using the larger of the 2 balls in the hole where the T piece and spring hold it In. That’s what I found in there, should I have used the smaller ball instead?

  14. Mike, I read an article that said you don’t need an accelerator pump if your front and rear carbs are dumps. The power valves are blocked off and there are no PV stems. What is your take on this. Regards, Mike

    • If you are referring to a tri power setup, then you don’t need a pump on the ourboard carburetors. Typically you don’t need the power valve.

  15. Mike, I rebuilt my 2cg with one of your kits. runs great. After shut down the carb drips gas from the throttle shaft. What causes this?

    • When there is too much fuel it will run out the throttle shaft. Now, why too much fuel. A couple of things might be happening. Fuel has a lower boiling point and the carburetor may be perculating. Engine gets hot, turn off the engine. The gas boils over. Make sure the fuel lines are away from the exhaust manifold.

      Flooding over could be the problem. More information on this is here:

      Check your spark plugs to make sure they are gray. Black means you are too rich, probably from a flooding situation.

  16. Hi, couldn’t find a phone number on your site to explain what part I need I will try and describe it to see if you can help me I am desperate.. During the cleaning process to rebuild I lost (off a 2g end carb) the following. The bell crank that operates the accelerator pump. The out side piece that has shaft and goes through carb top ( the rod from linkage hooks to this part) and the inside piece with set screw ( hooks to shaft and top of pump) any and all help will be noted thanks Len

  17. I have a 2g without the flush pump ball. There is an incline where a ball could set but no hole there. There is no hole in the tank for fuel to travel to the flush well. How does fuel get into the well? I watched several of the videos and I didn’t see this carburetor. I do have the large check ball in main discharge. My carburetor number is 7023010. Thanks.

  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

  19. 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!


  20. 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?


    • 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!


          • 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?


          • 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.

  21. 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.

    • 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

  22. 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.


  24. 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.

  25. 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.

  26. 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.

  27. 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.

    • 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.

  28. 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.

  29. 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

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

    Pat Mac

    Order # 5821

  31. 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

    • 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.

  32. 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

  33. 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.

  34. 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

  35. 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.

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