Would this carb be too small on a 455?

Discussion in 'The Mixing shop.' started by 69SkylarkGS, Oct 12, 2019.

  1. 69SkylarkGS

    69SkylarkGS Well-Known Member

    F238F6B9-6B27-4B3F-992E-EA02F65C64C6.png 9D7F92D4-069B-4878-8499-A4C3F9252F27.png CDA3DD4D-DD4D-47CA-9258-6C131A1539C8.png 9EB657C9-49EC-4031-8F7C-509011D319BB.png A32242BB-30A3-420B-824F-587C1F489002.png This carb is currently sitting on a Chevy 350 (30 over) the previous owner put in my 69 gs. It’s an AED 750 HP. It functions fine but is too much carb for an iron headed Chevy 350 with a mild cam. The previous owner spent 600 plus on this carb alone. I’m debating trying to use it on my 455 that I’m eventually going to swap in. The 455 would be mildly built (mild cam, aluminum heads if budget allows or cleaned up small valve 70 heads, ta headers, 2 1/2 exhaust etc.). Short block is a low mileage 70 but will need to be balanced due to coming out of an automatic car and going into a manual car. My other options are a 70 q jet off this same low milage engine. It’s in great shape but sat for years so will need a rebuild. I also have a q jet from a 75 455 that will definitely need a rebuild.
     
  2. DasRottweiler

    DasRottweiler -BuickAddict-

    I'm thinking it would be a good carb for a sbb 350 , you are going to want an 850 or above for even a mildly built 455. I have a Demon 850 on mine and am debating moving to a bigger carb.
    My experience, others will vary.....JIM
     
  3. 69SkylarkGS

    69SkylarkGS Well-Known Member

    Thanks for the reply, if your 850 isn’t enough I’m definitely going to run out of steam with the 750 then. It’s a nice set up but it seems like it’s too much for the Chevy 350 and probably not enough for the 455.
     
  4. hugger

    hugger Well-Known Member

    It will be fine for street use,..it will actually be very crisp and responsive
     
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  5. 69SkylarkGS

    69SkylarkGS Well-Known Member

    Thanks for your response, maybe I’ll give it a try when I get the engine together. I was hoping I could save some money with using this carb and free up some to put toward the heads. Too bad I missed out on those ported heads you were selling! One spot away lol. I’d love to go aluminum but the Buick heads are so expensive. The heads on the motor are stock 70 small valves.
     
  6. sailbrd

    sailbrd Well-Known Member

    750 is what a Q-Jet is rated at. So the CFM should be fine for your motor. The tune will be far more important. As Hugger said it will be great on the street.
     
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  7. Mark Demko

    Mark Demko Well-Known Member

    A 2 bbl is more than big enough for a SBC:p
     
  8. 69SkylarkGS

    69SkylarkGS Well-Known Member

    BE1E6943-7D9C-4AB7-9FED-B84ADC7A6059.jpeg EBC545B0-D644-48EE-9616-F23EA6F0DD28.jpeg 83866177-C148-46DA-91A9-AAF74355F4BD.jpeg I know this thread is from last year but I’ve finally got my 455 in and am working on trying to get it ready to actually run. Any suggestions on a fuel line set up from a stage 1 fuel pump to this carb? Looking for ideas on what others have done with their Holley carb. Which adapter would I need to go to a braided hose or something similar?

    Also looking to clean up the throttle cable set up. The old set up that came with the car was some back yard engineering lol.
     
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  9. 72STAGE1

    72STAGE1 Runnin' with the Devil

    First bit of advice, Get rid of the spacer, the throttle for a stock setup will work after you shorten the cable at the pedal, and that’s not a bad fuel line setup for a Holley, anything else gets way more expensive and you definite want a BBB fuel pump. That is an annular maybe carb and was too much for his 350 because the power valve it has was too much,and the jet sizes too I’ll bet because this is more for strictly performance applications, there’s great info on the Holley site on how to tune this carb, it’s not like your more common Venturi based Holleys.......it will work very good in a stock to mild 455.
     
    Last edited: Apr 26, 2020
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  10. 69SkylarkGS

    69SkylarkGS Well-Known Member

    Fuel pump is a stage 1 from TA. The spacer raised my carb enough to be able to run with the intake. Unfortunately the fuel lines hit the top of the intake with out it. It’s a tapered 1 inch spacer. I’ll look into shortening the cable near the pedal and see if it helps. I planned on using the fuel line pictured. My question was geared more toward adapting that line to another line and then adapting that line to the outlet on the fuel pump.
     
  11. 72STAGE1

    72STAGE1 Runnin' with the Devil

    Yea I know exactly what you mean in the fuel line hitting, you have to tweak it just slightly with a tubing bender on both inlets for clearance, hose and clamps with a barbed fitting is the easiest way remembering to use a quality fuel filter in there somewhere.
     
  12. 69SkylarkGS

    69SkylarkGS Well-Known Member

    I’ll probably just do something simple for now to get it running but down the road I was considering running some type of nicer line. What size fitting is correct to attach to the outlet on the stage 1 pump?
     
  13. DEADMANSCURVE

    DEADMANSCURVE my first word : truck

    sure , run it . you already have it . see how it goes . then send one or both of the Q-jets to one of the guys to go through for ya . do a little comparison .
    and that looks like a standard downleg booster carb not annular . do you have the part number for the carb ? probably good idea to check specs on it , some jetting etc probably changed to work on the 350 SBC . do you know if there is a rear power valve ?
    and the tapered spacer may not work as good as you think on a dual plane edelbrock . the middle manifold divider could cause a problem . they were designed for the open single plane manifolds . a standard straight down ( 4 hole ) spacer may direct the air better . just common sense thinkin'-out-loud on my part there .
    and there are some similar fuel inlets that move the entry point back a little bit from the front of intake . may give you a little more room .
    edit : AED #750HPHO - found a little AED info on carb from a summit AED tech answer . originally came with #75 front jets and 4.5 power valve . #85 rear jets with power valve blocked off .
    holley specs just as a reference :
    standard 4779 holley 750DP - fr jets 71 , rr jets 80 , power valve 6.5 , nozzles 28/31
    holley HP 80528 750 - fr jets 72 , rr jets 84 , power valve 6.5 , nozzles 31/31
    holley 80675 ultra HP 750 ( probably closest to your AED ) - fr jets 73 , rr jets 73 ( with rear power valve ) , power valve (2) 6.5 , nozzles 31/31
     
    Last edited: Apr 27, 2020
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  14. Mark Demko

    Mark Demko Well-Known Member

    Looks like the same type AED Im running on my 350, mines an 850.
    Yes, the spacer does help with the fuel line, mine was hitting the runners also without a spacer.
    Heres a pic of my line set up on my 350.
    Larry helped out with the fitting sizes. IMG_0492.JPG IMG_0493.JPG
    The fuel line is braided Teflon with threaded fittings attached to my Rob Mc 455 fuel pump they put a 350 arm on for me.
     
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  15. 69SkylarkGS

    69SkylarkGS Well-Known Member


    I appreciate you posting the carb specs that will be helpful! My plan is to eventually have a Qjet built for my car. Unfortunately I just don’t have the funds to do everything I’d like to at once and I have this carb sitting around. As far as I know it was just bolted on the old engine out of the box so it should have the specs you posted. I guess I can switch the spacer if I don’t like it. I didn’t go with an open spacer bc the carb is on the smaller side for a Buick 455 and it is strictly a street car. It also only has small valve heads with a valve job and no port work.
     
  16. 69SkylarkGS

    69SkylarkGS Well-Known Member

    Thanks for posting up your set up! Looks good, that must be a dam healthy 350 with a 455 RobMC fuel pump and an 850DP! Wish mine was an 850 lol
     
  17. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    My fuel line between the fuel pump and carburetor is braided -6AN. I use the same fuel line to hook to my Q-jet. There are 2 ways to connect the Q-jet. This is the one I use. It will fit any 1972 and later Q-jet,

    https://quadrajetparts.com/adapter-inlet-fitting-p-366.html

    The other way, is to use this 5/8-18 inverted flare to -6AN male adapter fitting. You can use this with any year Q-jet,

    https://quadrajetparts.com/fuel-inlet-adapter-fitting-p-369.html

    BTW, the above fitting can also be used on the Stage1 fuel pump outlet.

    You can make a braided line with female -6AN fittings on each end. You can even run a billet fuel filter in that same braided line as I do. Jim Weise actually made that line for me when he did my current engine. This is my AED 1000HP carburetor and the fuel line,

    DSCF0049.jpg

    The braided line attaches to the male end,
    DSCF0046.JPG
     
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  18. 69SkylarkGS

    69SkylarkGS Well-Known Member

    This is exactly what I was asking about regarding the fuel line set up! Thanks again Larry, I need to drop ship you a case of your favorite beer with all my questions you’ve answered for me! I do appreciate it, picking up this car has been a steep learning curve for me but there’s no way to learn if you sit on the sidelines. I’d never even pulled a motor before this and now I’ve pulled a motor/trans and put one back in plus a whole host of other stuff.
     
  19. 72STAGE1

    72STAGE1 Runnin' with the Devil

    That’s great to hear, it’s how we all began Brother!
    Keep wrenchin’....
     
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  20. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    My pleasure, it's the main reason I come here, to help.
     
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