4 corner idle??

Discussion in 'Holley' started by allioop108, Apr 4, 2006.

  1. allioop108

    allioop108 Well-Known Member

    What exactly is four corner idle (I see this term with reference to holley carbs)? I'm guessing its a carb that has a secondary metering block with idle screws like the primary block has. Ok so what's the advantage to having 4 corner idle as opposed to 2 corner idle (my carb is a holley 3310-4 that I will be adding a secondary metering block to). Does one need a different base plate to go from 2 corner to 4 corner idle. The reason why I'm asking is because I just ordered the proform body kit from jegs, don't know if the secondary block will have adjustment screws and i was also going to just get their throttle plate and primary block as well. Since everything is apart i was wondering if I should put in a secondary block with idle screws if the proform one doesn't have them or should I just leave it alone?

    Allen
    allioop108@aol.com
     
  2. Jeff Kitchen

    Jeff Kitchen Well-Known Member

    Yep, that's pretty much all it is. The reason is that some higher HP motors need more air at idle. If you only had the front two to deal with, the front blades would be open too far and would uncover too much of the transfer slot. With 4-corner, you can put the blades where they need to be and still get enough air to idle a big motor. Whether you need it or not depends on your motor. If you need it, it helps.

    The base plate has to have the extra holes in it to feed the idle hole and transfer slot. Then you need a metering block with all the passages opened up.

    By the way, on a 4150 style, you have to flip the carb over to adjust the secondary throttle blades. There's a small set screw that keeps the secondaries from closing all the way. Set the front and rear blades so about 0.030" of the transfer slot is showing. Adjust all 4 idle screws the same number of turns out from seated. I ususally start with 1 to 1 1/2 turns, then adjust from there.

    Have fun.
     
  3. RAbarrett

    RAbarrett Well-Known Member

    Actually, the 4 corner idle allows all 4 barrells to feed fuel, allowing the manidold, if necessary to feed correct mixtures to all of the cylinders. The typical 4 barrel aftermarket intake cannt properly distribute the mixture to all of the cylinders without problems, and the 4 corner idle allows the carb to overcome potential manidold problems. The necessary air flow, though correct, does not allow for the extra fuel necessary. Ray
     

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