4 barrel or 2 barrel carb which gets better mpg

Discussion in 'General Tech' started by insane moto, Feb 13, 2009.

  1. insane moto

    insane moto wheelinrover

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    Jan 18, 2009
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    i got a 390 ford engine that gets about 8 to 10 mpg. i rebuilt the 2 barrel carb but i have always heard you get better mpg with 4 barrel if you are not in it all the time. is this true? do you have any other ideas how to get better mpg out of this monster guzler. thanks
     
  2. bowtieman55

    bowtieman55 Well-Known Member

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    Location:
    Elizabeth City, NC
    USUALLY, you'll get better mileage from a V8 with a 4 bbl carb. The primaries are usually a bit larger, and it puts less strain on the engine when you get into it. Just my .02
     
  3. sungoesdown

    sungoesdown Member

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    florence, sc
    Yes, in theory. If you can make yourself stay out of it, yes. Just like how a tri-power gets very good mileage also.
     
  4. Bullardbs

    Bullardbs Well-Known Member

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    I had a 2bbl on my 79 bronco and got better when i went to a 4 bbl
     
  5. insane moto

    insane moto wheelinrover

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    thanks what about a 1 inch spacer under carb will that help any?
     
  6. bowtieman55

    bowtieman55 Well-Known Member

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    it generally won't hurt
     
  7. UTfball68

    UTfball68 Well-Known Member

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    To answer the original question (as most have already)...yes the 4bbl will increase mpg's due to the 2bbl having bigger primaries. Only problem with that is...can you stay out of the other 2bbls...haha. If you can keep your foot out of it, then yes it will increase your mpg's...I normally notice a 2-4 mpg increase (although that's usually with an intake swap as well).


    As for the spacer...be careful what kind of spacer you get, do you want to add to your top end or bottom end? If you want to add bottom end, go with a 4 hole spacer, if you want top end, go with a one of those wide open square spacers. Also note, the taller the spacer you go, the worse your bottom end will become but the better the top end.


    I prefer to stay away from aluminum spacers due to heat transfer...so I run phenolic 4-hole 1" spacers on my rigs. I prefer to go with HVH Super Suckers...but they're about $100 a pop.
     
  8. insane moto

    insane moto wheelinrover

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    thanks some good info i appriciate it later.........
     
  9. Chris_M

    Chris_M Well-Known Member

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    Durham NC
    Maybe I'm missing something, the 4 barrel will have SMALLER primaries, hence the fuel savings, but huge secondaries. A 2 barrel, on the other hand, has 2 medium sized venturi, thus not the miserly gas sipping primaries, or the huge air gulping, power making secondaries of a 4 barrel.
     
  10. UTfball68

    UTfball68 Well-Known Member

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    You're right...my wording was a little confusing, implying the 4bbl was larger, but I meant for it to reflect the 2bbl...so I edited for correctness.
     
  11. insane moto

    insane moto wheelinrover

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    if i go with a 4 barrel carb what intake and carb should i go with? for example if i purchase a basic elderbrock 4 barrel intake what size carb would fulfill my needs for better mpg? any suggestions on a intake and carb combination?
     
  12. UTfball68

    UTfball68 Well-Known Member

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    For a basically stock build...I wouldn't exceed a 650cfm carb. I wouldn't even go over that for a mild build. I use a Holley 4150 650cfm electric choke vac. secondaries on all my rigs. Great carb and is great on the street or trail. Stay away from DP carbs for street use. As for intake, I think Blue Thunder has the best intakes for a FE...but Edelbrock is a suitable intake as well.
     
  13. insane moto

    insane moto wheelinrover

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    thanks
     
  14. insane moto

    insane moto wheelinrover

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    how much do you think the holly 650 and intake would cost new or used
     
  15. UTfball68

    UTfball68 Well-Known Member

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    Well I normally only buy new...and the Holley 650 is $355 new, and the Eddy Performer with satin finish is usually in the $220-250 range. The carb is pretty expensive, but you don't need a 4150 style carb and that will be cheaper (you could use a 4160 style...the 4150's little brother...just not as much tuning control)...there are some 600cfm Holley carbs out there in the $200 range new. As far as used parts...I usually try to stray away from used engine parts, because usually there's something not right about them. But I've seen 4150 650cfm certified rebuilt carbs on ebay go for $100, and I've seen used manifolds for as cheap as $25.
     
  16. insane moto

    insane moto wheelinrover

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    thanks for info
     
  17. UTfball68

    UTfball68 Well-Known Member

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    No worries...I'm pretty useless to this site, but when it comes to 73-79 Fords and FE, 335 series and 385 series engines...I like to think I can hold my own...haha.
     

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