Chevy Small Block: Carburetor Spacer - 15 Horsepower In 15 Minutes

A Carb Spacer That Truly Works

Wayne Scraba Mar 1, 2002 0 Comment(s)
Sucp_0203_01_z Chevy_small_block_carburetor_spacer Dyno 1/5

Over the years, plenty of magazine articles have been written about carburetor spacers. They all talk about how various spacer configurations work and have also delved into the various materials used to construct spacers-typically aluminum, phenolic resins, or wood. And for the most part (and from what many Chevy enthusiasts already know), there usually isn't much power in a spacer. Oh, you might find a horsepower or two in some instances, you can move the power band around a bit and help distribution in other cases, but for the most part, there isn't much extra grunt available from a spacer. Or is there?

Fast forward to today. A company called High Velocity Heads (HVH), led by Joe and Keith Petelle, have an new entry into the carburetor spacer business. But let's back up for a minute: Who are Joe and Keith Petelle, and what is HVH? Joe and his son, Keith, may not be well-known in the world of street cars, but it's another story in Winston Cup where they made a name for themselves porting heads and manifolds from 1980 to 1992. In addition, HVH designed a series of intake manifolds for Brodix and also created the layout for the Canfield big-block head. Currently, they primarily build carb spacers, but they also do limited amounts of custom work for short track applications and drag race cars (yes, they do work on iron as well as aluminum heads and will basically port anything that flows air).

The carb spacer designed and built by HVH is called the "Super Sucker." While at first glance it looks like a conventional four-hole spacer, a closer inspection reveals that it is a long way away from standard issue. For example, the material is a plastic composite-and the spacer isn't simply cast, it's machined. The area between the respective holes is carefully profiled. It certainly looks different. But how good does it work?

We discussed the matter with John Heida of Speed Way Testing in Richmond, British Columbia, Canada. Now, Heida knows his way around cylinder head and manifold flow. He designs and ports cylinder heads for drag race applications (primarily rules-restricted class cars) and, of course, fast street cars. We scrutinized the Super Sucker. Sure it was made from a very composite material, and sure, it was a 1-inch tall version. And yes, the top side (carburetor mount side) looked like any other four-hole spacer for a standard Holley flange. But the bottom (intake manifold side) was far different than anything we had seen before (see the accompanying photos). But how things look quite often don't equate to horsepower. So we asked Heida to test the Super Sucker on his SF901 dyno, using a very typical small-block.

The engine in question was a relatively mild, 355ci small-block Chevy with a set of small valve heads reworked by Heida. If you check the Volumetric Efficiency of the engine coupled with the brake specific, you'll find that the engine is a pretty efficient piece, considering its docile inventory of components. Data was corrected for 29.92 inches Hg, 60-degree F dry air. The tests were done in a conventional A-B-A format (for the sake of simplicity, we haven't included the final back-up test-it matches the first test exactly). The baseline test results are as follows:

Peak in baseline configuration was 432.4 hp at 6,500 rpm. Maximum torque was 402.8 lb-ft at 5,000 rpm.

The second test duplicated the first, with the only addition being the HVH Super Sucker carburetor spacer. Results are as follows:

As you can see, the small-block peaked at 447.3 hp at 6,400 rpm, while the maximum torque of 413.2 lb-ft occurred at 5,000 rpm. In comparing peaks, the Super Sucker added 14.9 hp and 10.4 lb-ft of torque (again at peak).

Our assumptions regarding carb spacers at that point went out the window. And keep in mind, this wasn't a 2-inch-tall spacer. It was a simple 1-inch-tall job. In theory, the 2-inch-tall model should have made even more power potential. So how in the world does this thing work? We asked that same question of Keith Petelle of High Velocity Heads: "These spacers work, obviously, by helping the fuel distribution. If you look at the bottom of the spacer, you'll see that the shape is different. The reason for that is we wanted to improve the feeding of the outside runners on a single, four-barrel manifold. The design picks up the air speed and gives it a specific direction. Finally, the plastic composite material insulates the carburetor."

HVH machines all of their spacers from solid plastic composite stock on Haas CNC-mill equipment. They offer 1-inch and 2-inch-tall, four-hole spacers for 4150 Holley carburetors; 1-inch and 2-inch-tall, four-hole spacers for Holley Dominator carburetors; open, 1-inch-tall spacers for Holley 4412 carburetors; and two-hole, 1-inch-tall spacers for Holley 4412 carburetors. At present, they don't have any other spacers planned, however, if they have sufficient interest, they may consider creating several different spacer designs for Rochester Quadrajet-style carburetors. These spacers aren't exactly cheap, but they do provide cheap power. But in a well-sorted engine, 15 hp for 85 bucks certainly could be considered a bargain.

In the end, our preconceived carb spacer notions were definitely wrong: There is power from a carb spacer, particularly if it is of the HVH Super Sucker configuration. This thing might be the cheapest, easiest horsepower you'll ever find.

Sources

High Velocity Heads
865-573-9151
www.HighVelocityHeads.com
Speed Way Testing
Richmond, BC
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