anyone experience using 400-500 cfm 4 barrel vs a 2 barrel model 2150 on small block ford/chevys...?? better mileage with 2 or 4 if you dont have your foot in it?.... thanks for your time
I never put a 4bbl on the 0.030 over (but otherwise stock) 302 I had in the MII I had in high school/college, and I can't say I never kept my foot out of it... but I could never get better than 12.9 mpg from that car. This was with a C4 behind it and 3.00's out back, but tiny 185/70/13 tires. Oh, and I had duals put on it and the smog junk removed. In contrast my 52 Chevy sedan with a mild-cammed 0.030 over 350 SBC, and a Holley 600 with a Muncie 4spd and 2.73's got 22.9 mpg coming home from the RoundUp in 2006. I wasn't keeping my foot out of it then, either.
A small vacuum secondaries four barrel will win out in the gas mileage department. I'd go with a 600cfm Holley for a decent blend of power and economy, or a 390cfm Holley if you want to squeeze the most economy out of it. Either carb will bolt onto a standard squarebore 4v intake manifold. The Holley 500cfm two barrel runs real strong on small block Fords, and affords you the use of the stock 2v intake, but it won't get the gas mileage that a 600cfm four barrel will in everyday driving scenarios. The 350cfm two barrel did good on the 302 in my old van, about 14mpg on average and enough power to get it onto the freeway easily enough, but a 600cfm 4v woulda probably still done better in power AND economy. I've used Holley, Carter, Edelbrock, Motorcraft and Rochester 4v carbs on small block Fords over the years, and the 600cfm Holley always seemed to be the best all-around choice for these engines. I've also run stock Motorcraft 2v carbs and Holley 500 and 350cfm two barrels. Again, the two barrels run strong, but use more fuel doing it. Just my personal observations...take what you will from them.
My 63 1/2 Falcon convert runs a mostly stock 68 289 with a 500 Edelbrock 4 barrel on a Ford manifold. Doug's long tube headers and a PerTronix Plug and Play dist. 4 speed OD manual trans with 3.0 gears. Gets 24 MPG. With the original 2 bbl it got around 20. In fact it gets better than the 62 Ranchero with a 200six, headers, C-4 and 3.0 gears got! And a ton more power
my f150 has a 2bbl 302/aod and actually gets ok mileage, for a old truck. lacks in power, though. I would bet a 4 bbl would be better, cause you could accelerate faster and get into a higher gear faster, thus better mileage. The foot does decide, though.
Get a good dual plane intake and a small 4v carb. It'll beat out the OEM or other 2V carb combos most of the time. We've had several customers and friends swap from the original Motorcraft 2V/iron intake to a Performer or even an OEM iron 4V intake and gain both power and mileage. I run a 525 Street Demon on my '69 F100 shortbox with a chinkonese aluminum Performer clone on the 289 and we got 20+ on the way back from the Showdown with choked up exhaust and a load in the bed. -Bigchief.
When I put a 302 in my 66 mustang I first used the 2 barrel that came with it. I later installed a holley 600 cfm on it and did not notice any decrease in mileage, as long as I drove it without a heavy foot. The mustang is a light car however. Of course in the late 70's and early 80's when I had the car, I didn't really care about mileage.
I vote for an Edlebrock 600. I have on my daily 289 and get around 15mpg I'd say. Its got a C4 with 3.73's and 195/75/14. Keep out of the secondaries and it will do you good. Plus its very user friendly, I haven't adjusted it since I set the idle when it came out of the box 3 years ago.
I switched my 289 from a factory 2 barrel to a 500 cfm Edelbrock carb with electric choke, Edelbrock intake and a Mallory electronic distributor. It was the best move I could have made. Starts quicker,idles smoother and runs better...better mileage also..Mike
Going from a factory 2 barrel to a factory 4 barrel cast iron intake with the stock approx 450 Autolite 4 barrel the 4 was slightly better and plus about 20-25 hp on my old 72 Ranchero, right at 20 mpg hiway 17 city
Changed from the stock 2 bbl carter on my 318 ('68 fury - heavy car) to a Torker and 0-1850 holley (the generic speed shop 600 vac sec) that I had lying around. Was jetted a little too fat (never bothered to change it), and still got the same or slightly better mileage. Ran better, too. -bill
The 2 barrel he's referring to is as large as a 4 barrel and I don't think anyone makes a 2-deuce manifold for this carb and 3of these carbs won't fit........
Thank you all very much. Now does anyone know who sells 4 to 2 carb plates to use a 4 barrel on a 2 barrel manifold? or That would be to restrictive for the 4 barrel? Seems like the 500-600 cfm 4 barrels get better mileage then the stock motorcraft 2bl, also seems thats in combo with gears from 2.73's- 3.00's ANYONE RUNNING DIFFERENT GEARS? I have 302 2 bl motorcraft c6 and 3.73's out back..... thank you again
The 2 to 4 adapters are available but you don't want one! They just really screw with the flow and you won't get the benefits of the 4bbl. Get a good dual plane manifold like the Edelbrock Performer for best mileage and power increases, or if you want to save dough, find a used early stock Ford dual plane.
I'm getting about 15 in my wagon, stock '66 289/C4 with an Edelbrock Performer intake and a 600 man choke Holley at 3800lbs and 3.73 gears.
Not to hijack a thread but what about performance?. I had a stock 289/c4 in a 66 mustang fastback with a 2bbl and it ran great.headers, dual exhaust and electronic ignition. Then i had a 67 cougar with the same motor 289/c4,headers,,dual exh, and i installed a mild cam,roller rockers,aluminum intake,edelbrock 600cfm, electronic ignition and it seemed to run about the same as the mustang..?(weight maybe?) both had the same rear end too.. seems like rear gears make alot more noticable change than anything,when hunting for kick in the pants change.
Quick question, with a 500-600 cfm 4 barrel and intake (which I want to put on) Might have the problem of not passing smog? or any experience in that area.. Mean I could add another cat on the exhaust? thank you...and seems like the rear gears make a difference in mileage as well as the 4 bl carb n intake..
I have a Mustang I took the iron manifold and two barrel off and replaced it with an Edelbrock manifold and Holley 600cfm 4 barrel with vacuum secondairies. It performs better and gets about the same gas mileage. Better if you keep your foot out of it, worse if you don't. Don't bother with the two barrel unless your gonna put two more on
One point to consider... A vacuum operated 4 barrel (which is what you want in this case) will only open the back barrels as engine needs dictate. Since you are running a small engine anyway, the back barrels will almost never be used. Get any vacuum operated 4 barrel and a good intake like a edelbrock performer and you won't have any regrets. As for emissions, it depends on your state. My state has a 30 year moratorium. Anything older than 30 gets a free pass.
I did the 2bbl to 4 bbl swap on a 71 Maverick, the 4bbl ran better and the mileage dropped from 20 to 18. Later I swapped a 500 cfm 2bbl on a 75 Ford F100. The mileage dropped by about the same +/- 2mpg. It did run better with the larger Holley at cruising speeds or above. All of the above used stock cast iron manafolds. In both cases I had to lean out the primarys by about 3 jet sizes. Also on a 350 Chevy the 500 cfm 2bbl needed smaller jets as well, although I think I only went down 2 sizes. If you are putting a 2bbl on a 4 bbl intake with an adaptor, be sure to make a plate that can block each side from the other. Otherwise you end up with one hell of a low speed bog, as there is so much open space between each half of the intake. If you have to use a stock spacer plate for the PCV to feed in, keep the opening less than one square inch at most, if you decide to message the casting. ( They are very rough inside and have a ridge in them from the missmatched casting cores.)
have a 1971 ford E-200 high top,drove from Idaho to the east coast to my sisters,while there i put on headers new manifold and a holley 600 cfm holley,got 14 mpg going east and 10 mpg coming back to Idaho,so i went back to stock manifold and 2 barrel
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