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Hot Rods Edelbrock 650 thunder AVS on 273 mopar ?

Discussion in 'The Hokey Ass Message Board' started by Rustytoolss, Jul 17, 2014.

  1. Rustytoolss
    Joined: Jul 27, 2009
    Posts: 252

    Rustytoolss
    Member

    I've used the carb calculators and know the 650 Edelbrock thunder AVS that I have is to LARGE for my dodge 273. This carb is left over for another build.
    The caluclators come up with 380-475 CFM @ 5500. I've got the smallest Summit cam, Electronic Ignition& adjustable vacuum advance. Edelbrock performer intake, dual exhaust (not headers).
    Can the 650 thunder AVS work well on my 273, if I rejet/and rods ? I never run hard, just cruise. I'm always looking for better MPG. Or will I be better of buying the Edelbrock 500 thunder AVS ???
     
  2. gimpyshotrods
    Joined: May 20, 2009
    Posts: 18,490

    gimpyshotrods
    ALLIANCE MEMBER

    Get a Holley 350 2-bbl.
     
  3. Rustytoolss
    Joined: Jul 27, 2009
    Posts: 252

    Rustytoolss
    Member

    My comb is setup for an edelbrock carb, all my linkage,etc. So not going to rework everything.
     
  4. Rustytoolss
    Joined: Jul 27, 2009
    Posts: 252

    Rustytoolss
    Member

    anyone had any luck using a 650 on a small V8 ?
     

  5. gimpyshotrods
    Joined: May 20, 2009
    Posts: 18,490

    gimpyshotrods
    ALLIANCE MEMBER

    You can get a simple adapter.
     
  6. woodiewagon46
    Joined: Mar 14, 2013
    Posts: 1,918

    woodiewagon46
    Member
    from New York

    I would go by the advice that every carb builder, Edelbrock, Holly etc. puts out. Personally I think a 650 CFM carb is quite big for a 273. Reminds me that when we were kids we put dual quads on a 283 Chevy and it ran slower. It ran great with one four barrel so it should run faster with two, not so.
     
  7. gimpyshotrods
    Joined: May 20, 2009
    Posts: 18,490

    gimpyshotrods
    ALLIANCE MEMBER

    The front-half of that 650 is 95% of what that engine needs, at redline.

    If you must run a 4-barrel, get a vacuum secondary 390, 450, or 500.
     
  8. stimpy
    Joined: Apr 16, 2006
    Posts: 3,547

    stimpy

    Gm ran 750 quadrajets on 305s , Ford ran 600's holleys on 283's and 302's , a carb will only pull what it needs , you might not open the secondarys but with a high vacum number or some weight tuning they might open , you definately will have to rejet it down as it might run rich .
     
  9. Rustytoolss
    Joined: Jul 27, 2009
    Posts: 252

    Rustytoolss
    Member

    Yeah I know that the 650 AVS will self regulate. But I'm thinking that even if I do jet it down, that the 500AVS would be a much better choice.
     
  10. gimpyshotrods
    Joined: May 20, 2009
    Posts: 18,490

    gimpyshotrods
    ALLIANCE MEMBER

    If those are your options, get the 500.
     
  11. stimpy
    Joined: Apr 16, 2006
    Posts: 3,547

    stimpy

    500 would be more responsive when you kick it to pass some one . do not forget holley still makes the 390 -4 barrel vacuum secondaries . that would fit the bill perfectly as it would keep the intake velocity up .
     
  12. Rustytoolss
    Joined: Jul 27, 2009
    Posts: 252

    Rustytoolss
    Member

    Thanks guys for your input.
     
  13. gimpyshotrods
    Joined: May 20, 2009
    Posts: 18,490

    gimpyshotrods
    ALLIANCE MEMBER

    Remember, "jetting down" just leans out the mixture. It does nothing for venturi size, or throttle plate size.

    Ideally, you want the highest possible velocity through the venturis that can be achieved, without causing a restriction.

    Remember, the vacuum produced is what draws fuel through those jets. Decrease the velocity too much, by having an air pathway that is too large, you lose the vacuum signal.

    Do that, and the carburetor will simply not meter or deliver fuel properly, regardless of what the size the jets are.

    You really do need a 390, or 400, or even a 2-barrel.
     
    loudbang likes this.
  14. 29essex
    Joined: Feb 24, 2007
    Posts: 199

    29essex
    Member

    We would recommend the Holley 390 for the 273. We have a stock running 318 and a stock running 360 that we put the 390 on. The 318 was running a 600 Edelbrock and the 360 had a 500 Edelbrock. Couldn't make either one run right. Ran way too rich and dumped gas into the crank cases. Did everything Edelbrock said to do and more but was never right.

    Both vehicles run way better and perform so much nicer you would think it was a different car. The 390 has been an almost spot on setup for the 360 and for the 318 it could stand downsizing the jets a size or two. If you need a manual choke setup All State Carburetor sells one online on their website and they also have the Holley adapter/extension piece for your Mopar linkage.
     

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