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Thread: converting a 2 barrel 258 to a 4 barrel

  1. #1

    Post converting a 2 barrel 258 to a 4 barrel

    I was in Auto zone today and I saw a 2-4 barrel spacer conversion made by spectra (I think) for $12. It said converts all 2 barrel carbs, by just a visual inspevtion it looked like it would work. I was thinking than I could get a small 4bbl with out computer controled stuff and slap it on killing two birds with one stone (really bad flat spot and computer controled crap) maybe even a few horses to boot. What do you think? I know it probably wont be smog legal but with a SOA I already have to look for *ACHEM* other means for an inspection sticker.
    thanks
    Steve
    also anyone know how many cfm a small block quadrajet is?

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    88 yj sahara, 5.5" RE SOA,x8000i warn,doestech shocks, ss brake lines 15x7.5 eagle alloys (gambler style), 32x11.5 scorpions,TJ flairs,red top,straps snach blocks ect...
    Its a jeep thing....and maybe someday my girlfriend will understand....
    AIM__ sigepteppres
    2012 jku black altitude edition, 1.75/.75 leveling kit lift, black rubicon wheels tires, warn x8000i winch mounted on stock bumper mount, evo full skid system, rubi rails

  2. #2

    Lightbulb

    You should double check the bolt pattern on the 2 BBL side of that adapter. It may only work for V8s with 2 BBL carbs.

    A cheaper way to go than a 4 BBL is the 2100 carb. It adds reliability and power over the stock Crapper BBD carb.
    82 Wagoneer Brougham 360/T176/NP208
    63 Honda CB77 SuperHawk305

  3. #3
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    Post

    Those adapters are nothing but a problem. Just when the carb has the fuel atomized the mixture must pass through the small inlet of the 2-barrel manifold and droplets form in the mix. At that point the engine just coughs and sputters. Swap to a Motorcraft 2100 or 2150 if you want to rid yourself of computer controls. Do a search on it and you'll find all sorts of info.
    75 CJ5 on 37s with other stuff

  4. #4
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    if I remember correctly, the quadraflood is 600cfm. I think this type of mod would only cause problems...too much gas. I have heard people swear by these though if they are tricked out. Are you building a racing jeep?

    Ken



    ------------------
    2001 Black TJ Sport with
    Goodyear Wrangler MT/R 33x12.5x15 on AR 767 15x8's,
    Ged's Rocker guards, Kilby gas tank skid, Kilby large inside rack, CB Rack, Radio Crack Sport CB, 4 tow hooks, tow strap.
    Near Future Mods (week of 08/13/01): RE 3.5" Superflex, RS9k's, JKS Q'erD's, Skid Row engine skid, Kwan Motorsystems a/c kit, sanden a/c, KEAT2.5.
    Long term mods (next couple of months): 4.56 gears, ARB lockers f/r, SYE, CV custom shaft (if I can wait that long).
    2001 Black TJ Sport with some dirt.

  5. #5

    Post

    no not a racing jeep but i would sure like to see one. But seriously i was just looking into this because I could probably get a 4bbl carb cheap-as in free- and since the spacer is only $12 i thought it might be a better altenitive to trying to re-rebuild my carb (just cant get rid of that flat spot nomatter what i do) and I heard that if you drive conseritivly than the offenhouser intake with the 350 cfm carb actually gets 10-13% better milage and it also give a horespower boost. I figured that the spacer might be a cheaper way to go, even if I only got minimal-no gains but lost the flat spot in the carb that would be great i mean it runs great now other than the sputter when I first hit the gas (kinda makes merging interesting with my crappy 3.07 ratio and 32's) Well thanks for the advice I was just looking to see if anyone has done this tye of mod.
    Steve
    5:30 in the morning


    ------------------
    88 yj sahara, 5.5" RE SOA,x8000i warn,doestech shocks, ss brake lines 15x7.5 eagle alloys (gambler style), 32x11.5 scorpions,TJ flairs,red top,straps snach blocks ect...
    Its a jeep thing....and maybe someday my girlfriend will understand....
    AIM__ sigepteppres
    2012 jku black altitude edition, 1.75/.75 leveling kit lift, black rubicon wheels tires, warn x8000i winch mounted on stock bumper mount, evo full skid system, rubi rails

  6. #6

    Post

    The "flat" spot is probably a problem with the timing/vacuum advance on the distributor, not the carb, although it could be the accelerator pump on the carb.

    Mileage increases vary GREATLY from vehicle to vehicle, region to region, driver to driver.

    I think that with the I6 engine, you wont get much help from an aftermarket intake.

    Again... check the bolt patterns on the 2 BBL side of the adapter you saw. The 2100 swap is much cheaper, will probably give you the power you want and remove the "flat spot" provided that you set your timing properly.
    82 Wagoneer Brougham 360/T176/NP208
    63 Honda CB77 SuperHawk305

  7. #7
    Registered drgonzo's Avatar
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    My friend just did a similar swap on his 258. Instead of just a spacer adapter, he bought a Clifford intake and placed a small Holley 4bbl on it. Totally took the computer out of the loop. Big increase in performance and about the same money as buying a new Weber.

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    92 Wrangler, 2.5"OME, 1" MORE Body lift, 3\8" shackle lift, JKS Disconnects, 32" BFG AT, 15x8 Rockcrawlers, 4 3\4 BS, TJ Flares, Gibson SS Cat Back Exhaust, TC Air Intake, K&N air filter, TC Thermo Housing, Poweraid TBS, Random Technology CAT, D30 Front, D44 Rear, JB Conversions SYE, Tom Woods Driveshaft
    03 WJ Laredo

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