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Right Carburetor

Discussion in 'Early CJ5 and CJ6 Tech' started by Roberts1969CJ, Jun 22, 2016.

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  1. Jun 30, 2016
    1960willyscj5

    1960willyscj5 Well-Known Member

    Mesa, Arizona
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    Gotta tell ya - the first time I saw the subject title "Right Carburetor" , my first thought was 'What about the left one?'
    Now every time I see this thread, that flashes into my head.
     
  2. Jul 1, 2016
    eti engineer

    eti engineer Member

    Great Central...
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    Used to have a VW engine with dual carbs and that crossed my mind, too...
     
  3. Jul 2, 2016
    CJ Joe

    CJ Joe Truckhaven Tough!

    Pinon Hills, CA
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    This thread and many others refer to the Offenhauser 360 manifold. What is not mentioned is which one. There is the standard(?) and the Dual Port. The Dual Port has a clever design feature that increases performance when the secondaries are closed. I was wondering if everyone is aware of this.

    BTW I run a Holley 4160 (8007) on a Offy Dual Port. I've done a number of off-road modifications to the carb although it will run well right out of the box. I only use the jeep on the trail and that usually means between 1000-1500 RPM so I seem amused by all the talk about CFM.
     
  4. Jul 2, 2016
    tarry99

    tarry99 Member

    Northern California
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    Have ran them both............the dual port is a clever Idea that on paper is a great Idea but in reality doesn't do much........I like the standard 360.
     
  5. Jul 4, 2016
    RATTYFLATTY

    RATTYFLATTY I think you need a little more throttle

    Central MN
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    I'm running a Dual Port because it was on the motor when I bought it.
     
  6. Jul 4, 2016
    Focker

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

    WA
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    Me too.

    "Correct Carburetor"
     
  7. Jul 4, 2016
    47v6

    47v6 junk wrecker! 2023 Sponsor 2022 Sponsor

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    Just to continue the snakiness direction this thread is going in,

    The only reason I use the Offy intake and the holley carb is that my 2GC needed rebuilt and rebushed. I got the iffy intake NOS off craigslist for 50 bucks and the 8007 carb from summit for 415.00. That was in the ball park of a rebuilt 2GC. So there. MAX cfm and dork port performance at a budget price. I also got a complimentary gallon of blinker fluid!
     
  8. Jul 5, 2016
    1960willyscj5

    1960willyscj5 Well-Known Member

    Mesa, Arizona
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    Dual Port, or Dual Plane? Confused readers would like to know.
     
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  9. Jul 5, 2016
    47v6

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    DORK port i said!(y)
     
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  10. Jul 7, 2016
    Rozcoking23

    Rozcoking23 RUN & GET BIT! 2024 Sponsor

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    After running the second tank of gas and mostly in-town driving and some idling while messing with a new motor I averaged 10.7 miles per gallon with the standard OFFY 360 and Holley 8007 carburetor. This is with SM420 and 4:88's and WARN overdrive. As the motor breaks in, mileage should improve, (only has 202 miles on it).
    Truth be told, it could be getting 1mpg and you couldn't get the smile off my face as I drive it around!:)
     
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  11. Aug 9, 2016
    Dauntless1971

    Dauntless1971 Member

    Bend, OR
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    Some nice information in this thread. I had a line on a Holley factory rebuilt 390 but the deal fell through. Bought a new unused Offenhauser dual plane on ebay before things went sour. Now I am thinking about using a Edelbrock 500 just because the price is close to 150 less than a Holley. Started thinking about my collection of old Carburetors. And I dug up all that I have here at my house right now. Two Rochester 4 GC one is just for parts the other one appears to have been a working carburetor. It is older than my Jeep, but the smallest that Rochester 4 jets made rated at 486 cfm. I might have to find out what jets are stock on the 71 CJ with a 2 jet. I do not think any of my collection of Rochester 2GC came off any 225's. Maybe try to match them up in the primary's?
     
  12. Aug 10, 2016
    Jeepenstein

    Jeepenstein Me like Jeep..

    North Central FL
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    You beat to it.. And you are right assuming 100% VE which the 134 is far from, you kind of take a leap of faith there without having flow testing equipment. 90% is about tops for a production engine, I would assume the 225 would be closer to 80% given the rough castings and fairly small ports and lower RPM.

    Anyhow as Tim was saying a carburetor is a vacuum based mechanical computer using the logic that as velocity air increases is pressure decreases and metering fuel accordingly using the shape of the carburetor throat to "converge" therefore increasing velocity and decreasing pressure to "suck" fuel into the airstream. Smaller carbs (CFM wise) will generally produce better throttle response at lower RPM due to the smaller convergent section creating a better differential pressure due to the higher air velocity. Larger CFM carbs will be better at the top end due to not restricting airflow as much. It is a balancing act and then of course you have to mix in the metering of fuel and tuning that to the engine.. Carbs are brilliantly simple and complex at the same time.


     
  13. Aug 10, 2016
    montanacj

    montanacj Member

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    Great thread guys and very timely. As I get to know my new v6 the carb is the first project. The PO rebuilt it but it became apparent to me that something isn't right. When I actuate the throttle by hand I see no gas coming out of the venturi. Also I have gas dripping out of the vacuum port.

    I haven't had time to open it up yet but it baffles me as to why there would be gas coming out of the vacuum port? Any ideas as to why?
     
  14. Aug 10, 2016
    Jeepenstein

    Jeepenstein Me like Jeep..

    North Central FL
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    One of the best things I ever did was box mine up and send it to guaranteed carburetors in Florida. I can't say enough good about them. Came right out of the box tuned and ready to run..
     
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  15. Aug 10, 2016
    Dauntless1971

    Dauntless1971 Member

    Bend, OR
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    I found it the right carburetor is 7041185. I have a 7041105 on mine now. It was a rebuilt one from ebay for a 71 Chevy 307 it appears. I guess I need to find it it has the required 51 jet.
     
  16. Aug 10, 2016
    Jeepenstein

    Jeepenstein Me like Jeep..

    North Central FL
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    Well, you aren't wrong..
    [​IMG]
     
  17. Aug 12, 2016
    eti engineer

    eti engineer Member

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    What in the world is this in? That is one wild setup!!
     
  18. Aug 12, 2016
    colojeepguy

    colojeepguy Colorado Springs

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    Early 60's Chrysler 413 cross-ram.
    Works something like a tunnel ram intake but laid on it's side so you can get it under the hood.
     
  19. Aug 12, 2016
    ITLKSEZ

    ITLKSEZ Hope for the best, prepare for the worst

    Liberty Lake, WA
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    Fixed that for you. :p
     
  20. Aug 12, 2016
    47v6

    47v6 junk wrecker! 2023 Sponsor 2022 Sponsor

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    Yup. Thats funny and true. Seems to run better after I wrecked it and fixed it again.
     
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