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buick 225 v6 carb

Discussion in 'Early CJ5 and CJ6 Tech' started by mcastagnoli, Jul 29, 2010.

  1. Jul 29, 2010
    mcastagnoli

    mcastagnoli Member

    Cromberg Calif
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    Jul 21, 2010
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    13
    I have a 1971 cj5 with a Buick 225 v6. The carb is a rochester 2g, the id on the side of the carb designates it as a v8 model. Does anybody know if this is the stock carb if so what is the original jet size?
    Thank you
     
  2. Jul 29, 2010
    oldtime

    oldtime oldtime

    St. Charles,...
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    Aug 14, 2006
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    Seems like you have the wrong carburetor.
    Correct Rochester 2 GC numbers for Dauntless 225 are not the same as for other GM applications.
    What number 2GC you currently running ?
    Was your 1971 originally equipped with an air pump ?
     
  3. Jul 29, 2010
    rossbos

    rossbos Member

    everett wa.
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    Nov 10, 2002
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    The number on the carb should read 7041185
     
  4. Jul 29, 2010
    Dandy

    Dandy Member 2024 Sponsor

    Estherville IA
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    Feb 10, 2008
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    If you have the carb. no. I might be able to give the part no.'s.And app's.
     
    Last edited: Jul 29, 2010
  5. Jul 29, 2010
    Eaallred

    Eaallred Member

    West Valley City, UT
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    Oct 9, 2008
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    I robbed a 2g off an early 60's Chevrolet v8 from the junkyard, and after rebuilding it i'm getting 16mpg city out of it in my 62 CJ5 with stock drivetrain. Seems to work okay to me, if all you can find is one off a v8, run it!
     
  6. Jul 30, 2010
    WYOMIKE

    WYOMIKE Oct 1971 pic

    Parkman, Wyoming
    Joined:
    Jan 22, 2003
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    685
    Original jets for the 7041185-137-1-1 were:
    Sea level to 5000ft. .051
    5000ft. to 10,000 .049
    Over 10,000ft. .047
     
    Jonbbrew likes this.
  7. Jul 30, 2010
    mcastagnoli

    mcastagnoli Member

    Cromberg Calif
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    Jul 21, 2010
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    The number is 7029140 and yes it did run an air pump. Reason for post only getting 11 mpg
     
  8. Jul 30, 2010
    oldtime

    oldtime oldtime

    St. Charles,...
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    7029140 belongs to a 1969 Buick 350.
    Using a carburetor thats internally calibrated for a larger discplacement engine can cause the smaller displacement engine to run excessively lean. As in burnt valves !
     
    Last edited: Jul 30, 2010
  9. Jul 30, 2010
    Patrick

    Patrick Super Moderator Staff Member

    Los Alamos, NM
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    Huh. That's backwards from everything I've always known/ heard/ experienced.
     
  10. Jul 30, 2010
    Dandy

    Dandy Member 2024 Sponsor

    Estherville IA
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    Fwiw,
    I did some digging in my book, 7029140 is a 2GV, the 2GV is a auto choke model. However, a vac. break diaphragm unit(s) is used in place of the conventional choke HSG and choke piston. The thermostatic coil is located on the intake manifold and is connected to the choke valve by a linkage. The only 2GV listing in my book for a jeep is a 1968 Kaiser jeep 350 V8. Date of pub. Nov. 1971. I have the settings for that carb.#, but not the jet # 's.Sorry.
     
  11. Jul 30, 2010
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    Sep 23, 2002
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    12,529
    :iagree:

    How is a carburetor calibrated for a larger displacement engine which will require MORE fuel going to cause the engine to run lean?
    I'm interested in learning more...
     
  12. Jul 31, 2010
    mcastagnoli

    mcastagnoli Member

    Cromberg Calif
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    Jul 21, 2010
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    Anybody know where I can buy a Rochester 2g #7041185 ?
     
  13. Jul 31, 2010
    mcastagnoli

    mcastagnoli Member

    Cromberg Calif
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    Jul 21, 2010
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    dd
     
    Last edited: Jul 31, 2010
  14. Jul 31, 2010
    oldtime

    oldtime oldtime

    St. Charles,...
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    I base this statement on a couple of conversations I had with Jon Hargrove , proprietor of The Carburetor Shop.
     
  15. Aug 1, 2010
    oldtime

    oldtime oldtime

    St. Charles,...
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    An automotive carburetor is a device in which fuel is combined with air to provide an explosive mixture.
    This mixture can be lean, neutral or rich.
    The rich mixture is proportionately high in hydrocarbons while the lean mixture is proportionately high in oxygen levels.
    Higher oxygen levels produce higher burn temperatures which potentially can burn the valves.
    More air = more oxygen = increased combustion temperature = valve burn.

    The internal combustion engine is basically a vacuum / pump.
    Crankshaft revolution is derived from gaseous pressure either lesser or greater than atmospheric pressure.
    Vacuum pulls in the charge while charge combustion pressurizes the chamber.
    As engine displacement goes up so does the charge volume which is rated as CFM.
    CFM need raises proportional to engine displacement and the crankshaft velocity.
    The charge mixture is effected by heat and air velocity.
    Since the temperature remains relatively constant the main way to effect the mixture is via air velocity.

    In order to increase the CFM, a carburetor designed for a larger engine will utilize a larger throttle bore.
    When increasing the throttle bore diameter it should be fairly obvious that the air volume will be increased.
    This larger throttle bore allows a greater volume of air to pass.
    The venturi size is also increased to handle the greater CFM.
    When a carburetor having an over sized throttle bore / venturi is used,
    the air velocity decreases because the CFM requirement decreases for an engine with less displacement.
    When air velocity decreases, the air / gasoline mixture becomes effected.
    Decreasing the air velocity fails to properly atomize the gasoline.
    Within the carburetor there are several circuits .
    Except for the accelerator pump circuit more gasoline needed to enrich the mixture is available only via vacuum.
    Vacuum at the venturi is reduced if the air velocity is decreased.
    This results in a lean mixture because the amount of air to gasoline is increased.
     
  16. Apr 16, 2017
    youngjt7144

    youngjt7144 New Member

    Orange City, Florida
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    Jan 17, 2012
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    I know this post is from 7 years ago but what did you do with the 2g V8 carb?
     
  17. Apr 16, 2017
    colojeepguy

    colojeepguy Colorado Springs

    At the foot of...
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    7,110
    The OP hasn't been on here since 2012, so I doubt you'll get a response.
    If you need a carb, best to post a "want to buy" in the classified section.
     
  18. Apr 16, 2017
    montanacj

    montanacj Member

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    That lean comment makes sense after @oldtime explained it. Burned exhaust valves are a real concern even on modern cars. My 2004 Subaru burned an exhaust valve, thankfully it took 200000 miles to do it and I had virtually no other problems with the car till that point.
     
  19. Apr 16, 2017
    Steve's 70-5

    Steve's 70-5 Active Member

    Louisville, Ky
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    After read this thread, checked my Carb. # 7036146. Should I use it or start looking?
     
  20. Apr 16, 2017
    Focker

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

    WA
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    Sounds like you should start looking.

    Here's a chart - Post #49
     
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