carb question
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New User
Joined: Jul 2004
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carb question
Hey guys, would placing a 4 bbl carb on a 2 bbl intake with an adapter make a difference in performance and will i see a decrease in mpg on the highway. I have a stock 351m w/c6 tranny. plus any suggestions on carbs will be appreciated. Thanks.
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Joined: Apr 2004
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Less than you get now, assuming your 2bbl is not leaking gas. You will see subsquent posts about how a 4bbl gets better mileage because the primaries are smaller than the 2bbl. True. What they don't say is that holds only as long as you feather it and don't open the secondaries. Keeping your foot out of a 4bbl is an unnatural act. Can you pass the cookie jar without filching one? If you want more power, go with the manifold etc.
If you don't want to change manifolds, try a 500 CFM 2bbl, available at fine autoparts stores.
You won't get more power and better mileage in this situation.
If you don't want to change manifolds, try a 500 CFM 2bbl, available at fine autoparts stores.
You won't get more power and better mileage in this situation.
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Joined: Dec 2004
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From: Arvada CO
Allow me to offer some personal experience. 1977 F150 4x4, 351M/4spd, 3.50 gears, single exhaust w/turbo muffler. When purchased ran 6.5 mpg after tune-up. Switched to a dual plane manifold (2PSP by ??) and a Holley 600 cfm vacuum secondary. Also replaced the lifters with Rhodes lifters for more low end torque. First tank out ran 11 mpg, and smoked the tires out of the garage. Ran that set-up for fourteen years and my personal best was 14 mpg. Obviously the truck wouldn't run 12's in the quarter but drivabilty was better, efficiency was better, and when needed the power was there too. Also, the vacuum guage didn't help, it just took up space better used for a temp. guage or something...hope this helps.
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New User
Joined: Dec 2004
Posts: 12
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From: Arvada CO
"Get a Weiand or Edelbrock manifold and an Edelbrock 1406 carb."
One other thing, My dad had a '69 Lincoln Continental, 460 4V/ auto that did 16+ mpg hiway with the Edelbrock 1406. Pulled like an ox over the pass too.
One other thing, My dad had a '69 Lincoln Continental, 460 4V/ auto that did 16+ mpg hiway with the Edelbrock 1406. Pulled like an ox over the pass too.
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From: chicago burbs
if you can get the adapter plate to seal(not very hard with a quality piece, not a cheap universal) you can get some pretty decent results out of a 4bbl adapter set-up! the added availability of air into the stock manifold can provide an increase in velocity that rocks. it's not "the way it should be done" but if that's where you are in your budget and you're itchin to play with the linkage, vacuum hoses and fuel line then give it a shot. just don't damage anything to prevent you from putting it back the way it was, just in case it turns out that it's not for you. i've put together some adapter plate specials that for no explanation totally rocked! 2V manifolds on 4V heads, a stock spreadbore intake and a holley adapter on it with a 830 holley that had been mod'd up. but it was the right adapter with no extra holes, and it covered everything right-no leaks. i've done the 4bbl-2bbl adapter a couple times too, it'll work if you do it right. but i doubt that Ivan Stewart will be impressed?
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Joined: Dec 2002
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From: chicago burbs
it sure could! i worked over a stock 2bbl and was pretty surprised at the results. i did some work on the linkage that controls the accel pump and also increased the volume of the pump. i can't remember if i did much more to it? probably did though!
