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What size carb is most appropriate?

Discussion in 'The Garage' started by TRex, Jan 31, 2006.

  1. TRex

    TRex Registered Member

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    What size carb should i use on my 1986 chevy blazer with a new crate 350(stock),
     
  2. dave_90_blazer

    dave_90_blazer 1/2 ton status

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    600-650 cfm
     
  3. mechted

    mechted 1 ton status Premium Member

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    I saw a formula to ball park this somewhere:
    (Cubic Inches) x 2 x 0.85 = CFM then round to nearest size (up if "healthy")

    so 350 x 2 x 0.85 = 595 so a 600 CFM carb

    if im remembering this wrong someone please correct me!
     
  4. TRex

    TRex Registered Member

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    some guy told me that for a stock 350, a 500 cfm two barrel was best. Is this true?
     
  5. 78Suburban

    78Suburban 1/2 ton status

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    TRex, what part of Georgia are you in? Stock quardrajets were 750cfm. A popular choice with edelbrocks seem to be the 600cfm. I would think that a two barrel 500 cfm would not be very good for power.
    Thanks,
    james
     
  6. 1977k5

    1977k5 3/4 ton status Vendor

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    That .85 is for volumetric efficiency. A fairly built motor would be at more like .9, stock is probably .8. If you are going with a Q-jet, its 750 CFM will not be too much. If Edelbrock/Holley go with 600.
     
  7. TRex

    TRex Registered Member

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    I'm from Kennesaw, but I actually go to school in Kentucky. What about you? and what about a 600 Holley?
     
  8. 78Suburban

    78Suburban 1/2 ton status

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    I'm not too far from Columbus or Thomaston. Yeah a 600 holley will be fine, you whould look into the truck avenger series which is a great holley for offroad. The only downside I've ever heard about holley is that the old ones used to have power valves blow out if you ever had a backfire through the carb, but I've never dealt with a holley in real life.
    Summit has Edelbrock off-road thunder 650 cfm carbs for $350
    Summit has Holley Truck Avenger 670 cfm carbs for $410.. they also have a 470 cfm carb for the same price.
    Alot of people really like the stock Quadrajet Carbs, they are supposed to be the "poor man's fuel injection". Carb tuning is kinda confusing to me, so I got a little aggrivated with a q jet recently and am going to swap in my old edelbrock 600 cfm (soon to be converted to an off road carb with a cheap kit).

    Just do a little research. You won't be dissapointed with either one of the first carbs I listed from summit. You could always try to install TBI, so you won't have to fool with carb tuning. You just need to find a donor truck and get all the fuel injetction goodies off of it. Search around, there is more stuff than you could ever want to know on this website.
    Thanks,
    James
     
  9. mudjunkie 82

    mudjunkie 82 1 ton status GMOTM Winner

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    you can buy the truck avenger on ebay for a lot less than summit or jegs, I bought a new 770 cfm for 329.00
     
  10. TRex

    TRex Registered Member

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    Do you think that the Holley Truck Avenger 670 would be too much on my stock 350? would it flood it?
     
  11. 78Suburban

    78Suburban 1/2 ton status

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    I would imagine that this would be just perfect... I'm not sure if a 470 would be too small or not, just gotta seach around.. If it were me I think I would go with the 670.
    thanks,
    James
     
  12. dave_90_blazer

    dave_90_blazer 1/2 ton status

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    should be fine, espectially if you have headers/aftermarket intake, ect.
     
  13. TRex

    TRex Registered Member

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    Iv'e got headers and im gonna get an in take, right now it's stock, but I'm thinkin of getting the edelbrock performer.
     
  14. onetonbb74

    onetonbb74 1/2 ton status

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    i say stock q-jet. My holley floods out easier and uses more gas then a stock q-jet and has no power up steep hill climbs plus harder to start on the side of a hill. The q-jet is a poor mans fuel injection for keeping the engine running. Id grab an older style (no smog ****) rebuild it and run it. Plus all the stock stuff bolts to the q-jet. I like running stock closed box air cleaners when wheeling and an open air cleaner when driving around and the q jet makes it easy to swap cleaners.
     
  15. TRex

    TRex Registered Member

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    what kinda holley?
     
  16. onetonbb74

    onetonbb74 1/2 ton status

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    holley model 4150 i think. 30cc Double pumper, dual metering plates, 750 rated cfm, spring loaded needle and seats low fuel bowls dual fuel filters and pumps (helper and mech). Hate it off road, love it on the street.
     
  17. noahrob

    noahrob 1/2 ton status Author

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    I have a 383 with headers and will run a TA 670...
     
  18. TRex

    TRex Registered Member

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    do you think that a TA 670 would be alright on my stock 350 with and intake and headers?
     
  19. TRex

    TRex Registered Member

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    what size would a stock quadrajet be if it came on a 305?
     
  20. TRex

    TRex Registered Member

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    Were you using a Truck Avenger?
     

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