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Optimum 225 V6 carb?

Discussion in 'Early CJ5 and CJ6 Tech' started by Wenaha, Apr 5, 2014.

  1. Apr 5, 2014
    Wenaha

    Wenaha Member

    West Coast
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    Putting together the bits and pieces for a V6 in a flatfender. I will be using a SM420 and Dana 18 with 5.38 axles and 31" tires. Using Offy dual plane 4 bbl intake, 1-1/2" headers, HEI ignition. This is for trail use in rough country. Considering Holley Truck Avenger 470 or Marine 450. But I am very open to practical suggestions for this application, and I am sure there are many of you who have more experience with 225 V6s than I do.

    Thanks for your help.
     
  2. Apr 5, 2014
    Jeepenstein

    Jeepenstein Me like Jeep..

    North Central FL
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    I'm pretty partial to the stock rochester, but then again I have been eyeballing a 4 bbl when I do get my rig back to duty again so I am interested as well.. I was also looking at the truck avenger. I have the 650 version on my dodge and it ran great.
     
  3. Apr 5, 2014
    colojeepguy

    colojeepguy Colorado Springs

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    I have a TA 470 on mine. Works really good off road, & more power that the stock 2G carb, but has some driveability issues on the street that I've never been able to entirely eliminate.
    (I have a lot of experience with Holey carbs)
    I'm at 6500 ft elevation, so I'm sure that doesn't help matters.
     
    fhoehle likes this.
  4. Apr 5, 2014
    tarry99

    tarry99 Member

    Northern California
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    Your right about that 6500 ft mean elevation.......more so from the standpoint at that height the adjusted altitude / Air seems to vary much greater which in most cases likely goes to the higher side which riches the motor up.
    Like to try one of those Holley 470's some day.......what issues on the street do you have?.....................

    My old V6 that I built back in the 70's had the 470's much older cousin on it the little 390 cfm 4160 ......not quite as sophisticated as the 470 but after working on it for years I pretty much cleaned up most of it's old bad habits...........like the 470 has now years ago I built a copper tubed cross over bowl vent that cleared up the down and side hill flooding issues. Once modified I thought the little 390 cfm carb seemed well sized for the little oddfire.
    I do like the Holly's line in either case because of there large array of tuning parts & support.
     
  5. Apr 5, 2014
    djbutler

    djbutler Sponsor

    Rio Linda CA
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    I am very satisfied with the results from the stock Rochester 2G. I like the version with the manual choke.
    At extreme nose up angles on the trails I have encountered partial flooding, but not enough that it can't restart.
    On street driving the power is very adequate, plenty of acceleration for passing with the 4.88 gears.

    Don
     
  6. Apr 5, 2014
    Wenaha

    Wenaha Member

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    I am thinking that, with the intake manifold, cam, and headers I'll floe more air that a stock 225. I have no idea how much more, tho'.
     
  7. Apr 5, 2014
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    IMO the best carburetor is no carburetor.

    Some here have used the Motorcraft 2100 with some success on the 225. There is also a small sized Rochester Quadrajet that is reputed to be an excellent carburetor. The Quadrajet is very popular with the Wagoneer crowd, though it takes some effort to understand and tune. Both the Motorcraft and the Quadrajet work well on the trail.
     
  8. Apr 5, 2014
    gunner

    gunner Member

    Washington state...
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    First and only V6 I had was a 198 fireball I put in my 2A. Sold that in '73 and can't recall the carb.

    So I have limited knowledge of the right carb.

    But I do have a Motorcraft 2100 in the for sale section....
     
  9. Apr 6, 2014
    Wenaha

    Wenaha Member

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    I though a bit about TBI as an option. There is some messing around to do to get it to work correctly on an odd fire engine, I understand. Crank trigger and ECU tuning, etc.

    Since my manifold is a 4 bbl. I am thinking that this is what I'll end up with. Small 4 bbl. perhaps. Still undecided...

    Thanks for all your comments. Would like to hear from anyone with an informed opinion.
     
  10. Apr 6, 2014
    Jeepenstein

    Jeepenstein Me like Jeep..

    North Central FL
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    There's always the package EFI route like the MSD atomic EFI, but you better have deeeep pockets!
     
  11. Apr 6, 2014
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    Supposedly the Megasquirt is pretty easy to use on the odd-fire engines. It triggers from the tach signal, so you don't need a crank trigger wheel etc. Even in its simplest form (ie fuel only TBI) it would be a better carburetor than any carburetor.

    http://www.earlycj5.net/forums/showthread.php?46432-Mega-Squirt-on-Dauntless-225-V6

    You don't have to assemble the board - you can buy what you need already assembled, and just do the mechanical installation and under-hood wiring.
     
  12. Apr 6, 2014
    colojeepguy

    colojeepguy Colorado Springs

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    It has a part throttle stumble that I can't eliminate. In my younger days, I worked at a local speed shop, and I've set up literally hundreds of Holley carbs, but this one eludes me. I've changed squirter size, acc pump cam, power valve, monkeyed with the float level....it's better, but I can't eliminate it. It's worse when going around corners, but changing the float level doesn't seem to help. Right now, I'm running a #25 squirter & a #65 power valve with a small diameter brass wire inserted in the power valve channel to restrict fuel flow a little. The stumble isn't too bad, and I've just learned to drive around it. Doing a little reading on line, it seems that this is a common issue with these carbs, and it has something to do with Holley's redesign of the metering block to work at extreme angles. I will say that it works as advertised off road. I've deliberately put the Jeep at angles that were positively scary-left, right, forward, and back, and the engine just idled happily along. It also has a noticeable improvement in power over the stock 2G carb.
     
  13. Apr 6, 2014
    tarry99

    tarry99 Member

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    Hummmmm......Well you definitely have thrown the book at it...............Both Hot & Cold? Underseat fuel tanks can sometimes be an issue in corners? Fuel Pressure? Electric choke.......Have you checked that choke blade opening shortly after that occurs?

    Manifold? Type & Design?........Sometimes at low speeds and low cfm draw or transition the fuel can get out of suspension with the air.....clinging to the walls of the manifold.......and do weird things.

    That's a tough one.
     
  14. Apr 6, 2014
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    I have heard of the TA's drivability issue through other channels. Holley says in their sales literature that the carburetor is only suitable for off-road use, presumably due to this issue.
     
  15. Apr 6, 2014
    Wenaha

    Wenaha Member

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    Sounds good except for the stumble issue. So the stumble is off idle when the vacuum drops when the throttle opens wide SUDDENLY or does it happen when ever you accelerate from idle? Can these carbs be re-jetted to smaller jets? Sounds like they cannot...
     
  16. Apr 6, 2014
    Daryl

    Daryl Sponsor

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    I have put the 390 cfm 8007 carb on at least 10 different Buick v6s, 225s and 231s. There is a carb guy here locally that puts all of the truck avenger parts into the 390 carb and they run like magic. I put one of his carbs on a 71 with 225, T98, 18 with 3.73 gears and 32" tires and it got 18 mpg. You could point it up as steep a hill as it could make it and not flood out like a stock Holley will. For a street cruiser the 8007 in stock form is as good as a carb as I have seen on a Buick v6. One point is to not run a single plane intake on a odd-fire motor as I have seen some cross firing with one before.
     
  17. Apr 6, 2014
    Wenaha

    Wenaha Member

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    Daryl - sent you a PM.
     
  18. Apr 6, 2014
    colojeepguy

    colojeepguy Colorado Springs

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    I have dual tanks, under seat & in back, makes no difference. The choke works fine. The stumble occurs at the opening point of the power valve-I drove around for awhile with a vacuum gauge taped to the dash to confirm this. It's worse when driving at slow speed and trying to accelerate to a faster speed. If you're taking off from a standstill it's less of an issue.
    I have thought about the manifold issue-I'm running a Holley Street Dominator intake, which isn't a true dual plane-it just has a divider between the left & right halves. I'd really like to try one of the Offy split port intakes-I think the smaller plenum volume would help my situation.
     
  19. Apr 7, 2014
    Wenaha

    Wenaha Member

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    Thank you all for your help. I have a good idea of what I need now.

    Thanks again.
     
  20. Apr 7, 2014
    davistroy

    davistroy Grasshopper

    Marietta, GA
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    Let us know which way you go and how it works out!
     
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