Holley Blower Carburetors - Feeding The Best

Maximize Your Blower Carbs

Jason Walker Nov 1, 2001 0 Comment(s)
Sucp_0111_01_z Holley_blower_carburetors Carb_base_plate 2/14

Here's a quick and (you'd think) obvious tip: Always check the butterflies in the carb's base plate to make sure they open completely. The butterfly shaft on the left is not quite open all the way. This is mostly a linkage problem and can be solved with a slight amount of tweaking. Also, for this application it will be necessary to change the 750-cfm baseplate to an 850-cfm baseplate. This will allow a greater amount of fuel and air to be drawn through the blower.

With a giant blower sitting atop your hot rod's engine, you're going to get more than your share of attention from enthusiasts and those who'd like to throw a huffer on top of their ride. But when it comes to superchargers, it might be easy for the average "Joe" to overlook what's feeding that big chunk of polished aluminum its requisite amount of fuel and air. We're talking about the guy that may want to take the plunge and cut a big hole in his hood, but more than likely doesn't know the ins and outs of how a blower works, let alone how the carburetors need to be set up. So this "Joe" character sends away for a fully polished 6/71 in hopes of pumping out mega horsepower.

He's told that he'll need a set of fuel meters made (or reworked) to work with a Roots-style blower. Being an intelligent person (obviously a SUPER CHEVY reader), he orders two Holley blower carbs. Sounds easy, but in reality there is much more to it than just bolting the four barrels on and hammering the go-pedal.

The real science is figuring out the correct combination of carb components (jet, accelerator pump, idle feed restricters, needle and seat size, air bleeds, emulsion main circuitry, venturri size, and so on) to get the desired results. This can be an overwhelming experience to say the least. That's just the start, now figure into your growing equation, blower specs, hp and torque, cylinder head flow capabilities, and so on.

Sucp_0111_03_z Holley_blower_carburetors Taken_apart 3/14

The entire carburetor needs to come apart before we go anywhere. The beadblasted finish is how The Carb Shop prepares every carb they build.

Yeah, we know, it's hard enough to remember our own cell phone number without having to set up our own carbs, and this is why we contacted the gurus at The Carb Shop in Ontario, California, to help us understand just what is necessary when trying to build ultimate power from a blower motor. They were able to give us some insight to what makes a carburetor different when used on a supercharged engine.

The main idea here is to move a greater amount of fuel and air through the carburetor and still have a good deal of control over each. When the blower starts pulling on those carbs, it is going to use whatever the carbs give it. This is where the control factor is so important.

If you're planning to add a Roots-style supercharger (or even a centrifugal blow-through design), you need to learn about the specific requirements of the carb(s) you'll be using. Following are a few tips that O.J. of the Carb Shop taught us. Check it out and hold on when you mash that accelerator pedal.




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