Carb Adapter

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bucket

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I have used many of these to put a Holley/Edelbrock on a spread bore performer intake on my big block Dodge motors. Some say they are better on aluminum intakes but for what they cost it may be worth a try. A 1/2 phenolic or wood spacer on top of it may help with fuel percolation.

Those will only work on an aftermarket intake with a divided plenum. You can also stack 2 or 3 of them, with a gasket between each, to act as a heat insulator.
 

bucket

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Here's what I'm talking about with the 4-hole style adapter. As the primaries open up, one half of the butterfly basically feeds air straight into an aluminum wall. Once you hit around 75% throttle, it doesn't look to be too much of a restriction. But in the area where a vehicle is regularly driven (by the average person), that adapter really gets in the way of the airflow on one side of the butterfly. Maybe in the real world, it doesn't actually hurt anything on a stock engine. I don't know, I've never used the 4-hole type before.

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Sad Sack

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If you have deep pockets, spend the $$$ get the Holley spread bore replacement. They are pricey but direct bolt-ons. Your year would have used the List 6210 model, you'd have to research current offerings.

Current offering:​

Holley 4175 650 CFM 4-Barrel Carburetor 0-80555S


 
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