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Technical Tuning Rochester 2g

Discussion in 'The Hokey Ass Message Board' started by Squisbait, Apr 23, 2021.

  1. Squisbait
    Joined: Nov 22, 2020
    Posts: 91

    Squisbait

    I have a Rochester 2G in my O/T daily. It was bogging out rich on acceration. I put smaller jets in. When I get on it, it bogs out at about 1500 rpm, then picks up and hauls ass until about 2500, bogs again, then hauls ass again until about 4500-5000. Ive tried everything I can think of. Carb is fresh and not dirty, its getting plenty of gas also. Plugs are looking pretty black. Too small of jets kicking the power valve in? Jets still too big? Power valve not working right? I dont get it.
     
  2. Are you pretty sure it is NOT an ignition problem?
    A points ignition with a bad condenser?
    A bad coil?
    Mechanical advance not working?
    Other ignition related problems?
     
    Dino 64 and Truckdoctor Andy like this.
  3. Squisbait
    Joined: Nov 22, 2020
    Posts: 91

    Squisbait

    Ignition checks out.
     
  4. B.A.KING
    Joined: Apr 6, 2005
    Posts: 4,039

    B.A.KING
    Member

    A wise man once said,95 % of all carburetor problems are electrical??????
     

  5. larry k
    Joined: Feb 23, 2009
    Posts: 540

    larry k
    Member

    If you can’t fix it with a big hammer , you got a electrical problem!!!
     
  6. If it is not ignition related then check the Power valve in the carb is faulty, or you have a vacuum leak.
    Confucius: says, better check your ignition over twice, advance could be sticking
     
    jimmy six likes this.
  7. Squisbait
    Joined: Nov 22, 2020
    Posts: 91

    Squisbait

    I know the ignition is good, Ive tested everything multiple times and tried different coils, points, condensors, dist., Etc. Im thinking the power valve is dumping too much fuel possibly. What about grinding some off the button on the power valve to make it open less or eliminating it?
     
  8. A 2GC carb is pretty basic and should not require any modification to work ok.
    Tell us about the engine you are running.
     
    Hnstray and ottoman like this.
  9. Almostdone
    Joined: Dec 19, 2019
    Posts: 892

    Almostdone
    ALLIANCE MEMBER

    Dirty fuel filter, low float level or poor fuel pump? I know you said it had plenty of fuel, but what do you base that on?

    John
     
  10. Have you checked the diaphram on the advance? If it leaks because its 50 years old you wont get the advance you need.
     
  11. carbking
    Joined: Dec 20, 2008
    Posts: 3,710

    carbking
    Member

    Rochester released hundreds of DIFFERENT model 2-GC carbs for use on engines from 91 CID to 455 CID.

    Different internal venturii, different power valve actuator spring, different power valves, different gas and air jets.

    I know you said it was O/T, but if you would at least specify if it is original on the engine, and if the engine is basically stock or modified, would have a better probability of determining the issue.

    Jon.
     
  12. Elcohaulic
    Joined: Dec 27, 2017
    Posts: 2,212

    Elcohaulic

    Make sure the fuel line hose isn't collapsing when the carb is asking for more gas.. I sleeve all hose turns with 3/8" steel tubing.. Spray WD40 into the hose before sliding it over the tubing..
     
  13. Without talking about an OT ride, tell us what engine we are talking about (at least manufacturer and CID).
    Also, what is known about the carb's original engine installation.
     
  14. Squisbait
    Joined: Nov 22, 2020
    Posts: 91

    Squisbait

    Its a Volvo B23, 140 cu in, 10.3 compression, 227 degrees lobe separation, revs to 7k. I had dual Solex 1bbls on it for longest time but decided to go to the Rochester because the Solexes are a pain in the anus, but the Rochester is worse.
     

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  15. carbking
    Joined: Dec 20, 2008
    Posts: 3,710

    carbking
    Member

    PM sent.

    Note the second line in my signature block ;)

    Jon.
     
    pprather likes this.
  16. Jon, thanks for helping original poster.
     
    Last edited: Apr 25, 2021
  17. carbking
    Joined: Dec 20, 2008
    Posts: 3,710

    carbking
    Member

    Phil - I respect Ryan's guidelines, thus try not to deliberately violate them.

    However, us old geezers will have an easier time disposing of our rides when the time comes if we attempt to attract younger folks to the hobby; so try to answer the question, but do it with a P.M.

    Jon.
     
    pprather likes this.

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