tuning a holley 670 street avenger for a buick 455

Discussion in 'Holley' started by 72gsBuick, Apr 8, 2009.

  1. 72gsBuick

    72gsBuick Never Say Never..

    how woud you guys tune a holley street avenger 670 cfm, 4 barrel to perform on a buick 455 73 block 72 stage 1 heads, offy intake, and kenne belle headers, i have to work with a budget and i was thinking of reusing the holley for a while, but want it to perform good, somehow after acceleration it wants to hesitate a bit...i know its too small for the engine, but just want to know if its worth it to modify it for a bit, till i rebuild a 750 double pumper..thanks
     
  2. RG67BEAST

    RG67BEAST Platinum Level Contributor

    The avenger carbs run lean out of the box. Go with the DP 750 if it's all you have. But a larger carb is better. Sell the 670 and get a rebuild kit for the 750 if $ is an issue.
    Ray
     
  3. 71GS455

    71GS455 Best Package Wins!

    Most would tell you that the 750 is too small for the motor too. Sorry I can't help you with advice on the 670. I'd sell them both and get something bigger.
     
  4. No Lift

    No Lift Platinum Level Contributor

    Get yourself a cheap 1" open spacer. That will make the carb seem bigger to the engine. That would help some. The jetting up suggestion will also be worth it. Get yourself a Holley secondary spring kit. That carb should be a quick change spring holder and try the lighter springs until it bogs when you floor it. That small carb should work with almost the lightest.
    However your bigger problem is the Offy intake. They are actually worse than the stock intake unless you shift at 6000 and never let the rpm fall below 5500 rpm. They have a very narrow rpm band where they are slightly better than any of the other dual-planes out there. I'd get a stock intake with a Holley/Q-Jet adaptor or an Edelbrock. Anything you put on there will feel and perform noticably better. You'll pick up just as much or more changing the intake as you would by going to the 750.
    Any intake you use could use the spacer to help out the 670 and even the 750. Depending on where your best power is maybe a 4 hole spacer would work although that would tend to help the bottom end torque.
     

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