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Rochester 2g replacement options

Discussion in 'Early CJ5 and CJ6 Tech' started by peter, Aug 31, 2015.

  1. Aug 31, 2015
    peter

    peter Member

    Roseville, CA.
    Joined:
    Aug 26, 2008
    Messages:
    161
    I have the original Rochester 2g on my 67 225 v6. Reguilt 2 x in the last 5 years but it does not seem to work very well. Lots of deiseling and smell of fumes. I also have the Petronix and coil on it. It runs smoothly at speed but upon first acceleration there is a flat spot that if you do it just right will kill the engine. I am wondering if I am better off with starting over with a replacement Rocherster 2G? I realize that they are remanufactured but it seems like the rebuilds on mine have not made it work as it should. Summit sells these for $275. I have not fully checked the vacum situation and it could be that. There is a plug on the back of the carb that can crack and allow air in which is bad. These current symptons seem different. Or is this just modern gas in an old engine?? Any advice out there would be great.
    Thank you.
    Peter
     
    peter, Aug 31, 2015
    #1
  2. Aug 31, 2015
    Walt Couch

    Walt Couch sidehill Cordele, Ga. 2024 Sponsor 2023 Sponsor 2022 Sponsor

    cordele, Ga.
    Joined:
    Mar 29, 2007
    Messages:
    5,923
    By all means check for vacuum leaks first. A lot of carbs have been rebuilt by the owner that did not need to be because of bad dwell setting, fowling plugs, bad plug wires etc. Check everything else before condemning the carb.
     
    Walt Couch, Aug 31, 2015
    #2
  3. Sep 1, 2015
    Warkmeister

    Warkmeister Member

    Fresno, CA
    Joined:
    Jan 13, 2014
    Messages:
    63
    I just asked a question regarding my poor running 67 too...I've rebuilt my 2g a few times this week! One thing I did just find was that I had one header bolt loose on the pass side that was causing gunshot backfires. Walt is right in that we need to check things with gauges to rule out/pinpoint other issues.
     
    Warkmeister, Sep 1, 2015
    #3
  4. Sep 1, 2015
    Warkmeister

    Warkmeister Member

    Fresno, CA
    Joined:
    Jan 13, 2014
    Messages:
    63
    Forgot to add that I've also briefly researched a 2g replacement. Most folks say keep it, others say the best replacement is a motor craft 2100 or 2150 with the 1.08 venturis. Hope this helps.
     
    Warkmeister, Sep 1, 2015
    #4
  5. Sep 1, 2015
    Vanguard

    Vanguard Take Off! Staff Member

    Vista, CA USA
    Joined:
    Aug 30, 2006
    Messages:
    2,259
    I run a Motorcraft 2100 with 1.08 venturis.
     
    Vanguard, Sep 1, 2015
    #5
  6. Sep 3, 2015
    peter

    peter Member

    Roseville, CA.
    Joined:
    Aug 26, 2008
    Messages:
    161
    Thank you for the replies. I am also going to check the accelerator pump to make sure it is not damaged by the modern gas. Looks like it needs to be the ethanol resistant style to hold up over time. And the tune up parts as well.
    Thank you,

    Peter
     
    peter, Sep 3, 2015
    #6
  7. Sep 3, 2015
    Focker

    Focker That's a terrible idea...What time? Staff Member

    WA
    Joined:
    Aug 18, 2014
    Messages:
    7,540
    Don't give up!

    When rebuilding mine recently I didn't know I could remove the power valve with a screw driver until I was almost finished with the rebuild. I'm glad I did, there was crud trapped under it. The float wasn't set to specs either. Seven months prior I had disassembled and cleaned the carb but it always had the same problem you're describing unless I drove with partial choke on.

    Do yourself a favor and completely tear down the carb, buy an Ultra Sonic Cleaner for $80 at Harbor Freight and clean every bit of the carb.

    Do another favor and watch these 2 rebuild videos even if you know what your doing. I stood at my computer and followed along bit by bit. I can't believe the transformation in how my carb functions! I just bolted it on and only had to adjust the idle screw because it was backed off when pulling the carb.

    Part 1 of 2 - https://www.youtube.com/watch?v=K3rGkqxlKq0
    Part 2 of 2 - https://www.youtube.com/watch?v=WHuMKvtrbZk

    I was able to set the mixer screws to what was suggested in the video and bolt on and go! I want to say 1 and a half turns out from seated? My timing was set so a little idle adjustment and it runs like a top.
     
    Focker, Sep 3, 2015
    #7
  8. Sep 4, 2015
    MarkK

    MarkK Rita the Jeep

    S.E. Idaho
    Joined:
    Jan 1, 2008
    Messages:
    175
    [​IMG]

    make sure to check your carb to manifold gasket. Mine was blown out.
     
    MarkK, Sep 4, 2015
    #8
  9. Sep 4, 2015
    1960willyscj5

    1960willyscj5 Well-Known Member

    Mesa, Arizona
    Joined:
    Nov 27, 2006
    Messages:
    2,793
    Holley made a two-barrel carb that was a direct bolt-on replacement for the 2G. At least the one that went on the 1966 425 ci Olds engines in the Dynamic 88.
     
    1960willyscj5, Sep 4, 2015
    #9
  10. Sep 8, 2015
    peter

    peter Member

    Roseville, CA.
    Joined:
    Aug 26, 2008
    Messages:
    161
    As a final thought here, took apart the carb to check the accelerator pump and it was broken and in 2 pieces. Replaced it and the 2 main seals and the initial test and run went very well. Now I need to dial in the mix but it is very close and running smoothly again. Thank you for the advise on this great forum.
    Peter
     
    peter, Sep 8, 2015
    #10
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