Help me pick my next Carburetor please!

Discussion in 'Engine Topic' started by Vortec80, Mar 4, 2019.

What Carb should I use out of these?

  1. Holley 670 street avenger

    6.3%
  2. Holley 750

    68.8%
  3. My current Holley 600

    0 vote(s)
    0.0%
  4. Other...Please drop other suggestions in the thread

    31.3%
Multiple votes are allowed.
  1. G72Zed

    G72Zed Veteran Member

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    Basically the same specs other than the 3310 is Zinc material with manual choke and the 80508 is aluminum with electric choke.

    I’ve done several of the “low cost aluminum “ carbs, let’s just say you get what you pay for. I would go 3310 if you can swing the 115$ and don’t need an electric choke.
     
  2. 1980RS

    1980RS Veteran Member

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    If it were me I would go with a new 650 Brawler carb from Holley. I have a tricked out 1850 600VS that has run mid 11's and runs with my 850 Mighty demon almost to the hundredth. I also in the past used an 1850 600 Holley with less work that ran 11.63 with one of my BB 454's in the past, sure it won't rpm to the moon on the BB but on a SB it works great. Most Holley's need tuning and signal from the intake manifold to the booster IMO is the key to a good carb. I do not like the Avenger Holley's, the last 770 I worked on was a dog and when switched out with the old 3310-1 it was like driving a different car. Right now on my 68 Firebird I have had a few 600 Eddy carbs, all run down the road poor so I replaced it with a Holley 750HP VS (no choke) and the 350 runs perfect. All I did was jet it down.
     
  3. 92RS305

    92RS305 Keeping the sound of Cammed V8s alive and well.

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    Although maybe hard to source these days but original 68-70ish pre smog Q-Jet from Cadillac 472/500 (just block off the Hot Idle Compensator). Other sources GM Q-Jet for 400, 455, 396, etc.... The 80 Turbo 830 CFM would be another possible, before it went to 81 electronic carb. I had New 1980 GMC 350/TH400?4.10 4x4 Long Bed with Snow Plow Package, changed the Q-Jet to Holley 600 CFM Double Pump Mech Secondary, went from 7MPG to 12MPG and tremendous change in drivability. Sold the truck bought a 81 Turbo TA, changed the Q-Jet to a 650 SpeadBore Holley with Mech Secondary, changed both front and rear pumps to 50cc. Had I known then what I know now, I would have went with an 850 cfm. Yet with the 650, my 0-60 times went to 5 - 6 sec, mpg went up to 20mpg, and on the ride to Street Machine Nationals in '82 got 25 mpg on pump gas.

    Q-Jet and AFB (Edelbrock today) for daily driver.

    Holley for stomp romping and wheel smoke
     
  4. ZEN357

    ZEN357 Veteran Member

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  5. COPO

    COPO Veteran Member Lifetime Gold Member

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    If you buy the Holley 750 it comes with 72 prim jets so you'll need to step it down until you like the looks of your plugs. If it has a rear bowl then you shouldn't need jets larger than 76's. The reason for the 72 prim is to accommodate the BB guys.

    I'm running with my stock 780 Holley with 70 prim jets and 76 rear jets. My backup carb which I used for a good 15 yrs is a Holley 750 3310-2 that comes with a rear metering plate rather than a metering block. My tail pipes were always gray with the 750.
     
    Last edited: Mar 4, 2019
    1980RS likes this.
  6. G72Zed

    G72Zed Veteran Member

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    If it's a "new" 3310, it will (should) be a -10 or -11, and they now run 70 front and 75 rear in the metering plate. And your right COPO, the 3310 750's from -1 to -9 they were all 72 frt mj.

    FWIW, If using a good ignition setup and everything is up to snuff, the plugs may lead you the wrong way.
     
  7. 92RS305

    92RS305 Keeping the sound of Cammed V8s alive and well.

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    Is that the 1411? I used their filter and got >>> Edelbrock Performer Series 750 CFM Carburetor with Electric Choke - Part Number: 350-1411

    Holley has a CFM calculator: https://www.holley.com/retailer/carbselector/

    For a CID 350 "Highly Modified: Returned the following:

    350 CID @ 5000 Max RPM = 600 CFM
    350 CID @ 6000 Max RPM = 650 CFM
    350 CID @ 8000 Max RPM = 850 CFM

    Its a little bit of a misnomer, but originally all the Carter AFB were mechanical Secondaries. The Edelbrock is just a Carter AFB. AFB = Aluminum Four Barrel (some were zinc aka: "potmetal").

    Edelbrock now has the AVS which is the Adjustable Valve vacuum Secondaries. I have no direct experience with the AVS units, yet several I talked with had trouble with setup and or fine tune of them. They do have plus to them due to having two fuel inlet provisions and are more of a spreadbore design.

    Edelbrock is a great carb, I like the fact you can fine tune the primary side without having to open it up. Removal of the rods is at the top so you can do it even on a hot engine without dumping gas all over it. I don't like the fact of the Pump shot is fixed and the power valve doesn't give much adjustment. Likewise; because it is square bore you have to be more exact with matching the correct carb to the application or you have drivability problems.

    Holley you can fine tune every thing, but if you don't know what you are doing you have a mess. Yet Holley offers both square and spreadbore.

    Q-Jet once setup is real dependable until the plastic bushing on the primary shaft wears out and starts leaking air, but until then very dependable daily driver. The small primaries keep your idle vacuum acceptable and you get good economy. Then the secondaries open and you need to hit the gas station again and soon. Also the older foam floats tend to soak gas over time and then you get flooding and hard starts. You can get brass floats for Q-Jet $10.00 most places, but just one more thing to track.
     
  8. Chevyforever

    Chevyforever Veteran Member

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    Was just looking online at this "offshore" 670 cfm carb last night, seems to offer some good features ...



    Quick Fuel Brawler Die-Cast Series Carburetors BR-67256
     
  9. 1980RS

    1980RS Veteran Member

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    Just sold a NOS 3310-2 carb last year to a friend, he said it's the best carb he has ever run on his car. On my 350's I used to run 68 pri and a QF metering plate in the rear so I can change jets, I ran 73's, it worked out pretty good.
     
    92RS305 likes this.
  10. 70Chev

    70Chev Veteran Member

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    Hey mate. I have a very similar engine combo to yours and have just fitted FiTech fuel injection. The engine loves it and it is REALLY easy to install. A little more in terms of what you would spend on a carb but less tune ups etc. I love mine. Just a thought.
     

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