Carburetor Spacer Buyer's Guide - Breathing Room

The Carburetor Spacer Buyer's Guide

Sean Haggai Jun 1, 2009 0 Comment(s)
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If you haven't considered a carburetor spacer, here's something to keep in mind. They don't require much effort to install, generally have the potential to free up extra power, don't require any maintenance, and are pretty affordable. If you considered all the other aftermarket products on the market that offer the same power benefits, you wouldn't even be able to come close to the bang-for-the-buck that these spacers offer.

So what does a carburetor spacer do? In a nutshell, adding a carburetor spacer increases the intake plenum volume by creating a taller neck on the manifold. With the extra volume, the distance between the floor (bottom of the intake manifold) and the bottom of the carburetor is also increased. The extra distance allows for the intake mixture to straighten out. Along with the extra plenum volume, the intake runner volume is also increased, potentially allowing the engine to breathe more efficiently and ultimately make more power.

Considering the engine combination you've got is tuned correctly, it's safe to say that you're going to produce more top-end power while only taking away a little bottom-end grunt (think of a tunnel-ram manifold). Still, in high-revving engine combos that isn't necessarily a bad thing. Actually, reducing the plenum volume will give the engine more of an edge at lower rpm while taking away a bit of power up top in higher rpm. While open spacers add plenum volume, which can reduce low-end torque and extend the upper rpm range, a four-hole spacer will add low-end torque by increasing the air velocity. Of course, this is assuming the camshaft can help provide it.

Our experience with carb spacers isn't without proof either. In the past, the spacers have been a wolf in sheep's clothing, so to speak, and have landed us pretty solid numbers on some of our final dyno pulls. Take into account our three-way small-block shootout (Aug. '08). The Misfit 327 was impressive on pump gas, producing 380 hp. We thought that was all the little guy could muster up, until our comrades at the Westech dyno facility topped off our street mule with an open 2-inch spacer. The results showed an extra 11 ponies, making our final pull peak out at 391 hp.

So, in an effort to showcase what's available, we've compiled a list with detailed specs, including the price, dimensions, and what manifolds they fit. We've even listed which manufacturers offer a 4150-to-Dominator adapter plate. All said and done, the benefits vary by engine, based on various combinations, however there's a good chance something will be gained from it.

Quick Notes
What We Did

Compiled a list of what's available in an easy-to-read format with the vital specs you're looking for.

Bottom Line
They're affordable and a quick way to generate additional horsepower.

Starting at $15

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Trick Flow
These cloverleaf designs are offered for Dominator baseplates, this cloverleaf design promotes horsepower and torque in the mid-to-upper rpm range. These trick pieces are also available for throttle-body applications.

Notes: Comes complete, just install it.

Trick Flow Specialties

0906chp_03_z Trans_dapt_performance_products Carburetor_spacer 4/14

Utilizing Trans-Dapt's own Swirl-Torque spacer design, this phenolic spacer cuts down on heat transfer for a denser fuel charge. It is also available in 1- or 2-inch aluminum.

Notes: Comes with PCV valve nipple.

Trans-Dapt Performance Products

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JEGS High Performance
These Edge spacers are CNC-machined from a polycarbonate plastic, which reduces heat transfer and helps keep incoming fuel cooler. They're available in three heights. Also, try this spacer out with a 2.035-inch bore opening for 4500 Dominator carburetors.

Notes: 1.750-inch bore size. Can withstand heat up to 400 F. Will not work on stock manifolds with heat crossover.

Jegs High Performance

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Summit Racing
Plastic not only cuts down on weight, but it also serves as a heat barrier. Get these Summit spacers in 1/2-, 1-, or 2-inch configurations with your choice of cast aluminum or phenolic and either the open or four-hole design. Quadrajet spacers are also available for throttle-body applications.

Notes: Also help with linkage clearance when using custom throttle setups.

Summit Racing

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High Velocity Heads
Super-suckers are constructed out of solid billet, and these pieces would crown any engine build. This version is a lightweight 2-inch design, utilizing a four-hole tapered design. The coolest part? This spacer will convert your 4500 carburetor so that you can plant it on any 4150 intake manifold. That's right; it's an adapter and spacer all in one.

Notes: This version is CNC'd to eliminate unnecessary weight, making this spacer extremely light.

High Velocity Heads

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JET Performance Products
The Power-Flo takes the lead in Quadrajet performance. The bore is designed to increase the velocity of airflow into the intake manifold. These are high-quality billet pieces, and it's important to note that JET also has seen larger gains when combined with its own programmers and intake kits.

Notes: Carburetor specific spacers are also available.

JET Performance Products

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Cast out of aluminum, these kits come complete with gaskets and mounting hardware for an easy install. Holley also offers a four-hole, phenolic, 1-inch configuration. Try out Holley's 4150-4500 adapter plate as well.

Notes: Comes with PCV valve nipple.


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Wilson Manifolds
Wilson's spacers use a variable-radius taper design to maximize airflow through the carburetor, which enhances air and fuel flow. Wilson provides a complete line of four-hole tapered spacers for 390, 4150, 4500, Q-jet, and two-barrel adapters.

Notes: Compatible with alcohol.

Wilson Manifolds

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Jomar Performance
Made from an advanced phenolic laminate, Jomar's Power Cone spacers prevent significantly less heat to the carburetor. Get these in either 4150 or 4500 baseplate configurations in 1/4-, 1/2-, 1-, or 2-inch designs.

Notes: Jomar also has more carb spacer styles to choose from.

Jomar Performance

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MR. Gasket
This two-in-one carburetor spacer kit includes the aluminum spacer, two phenolic inserts and two gaskets, and all the carb-mounting hardware required for installation. This kit from Mr. Gasket gives the user the ability to choose between an open-style insert and a four-hole design. Since both are phenolic inserts, these will also reduce temperatures, keeping the fuel cooler for added power.

Notes: Fits Holley, Edelbrock, AFB, and Carter four-hole and open manifolds. Traditional-style spacers and adapters are also available.

Mr. Gasket

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Edelbrock is well versed in manifold design, so it only made sense for the company to provide products for fuel and air distribution too. Available in aluminum and heat-insulating phenolic or wood fiber, these Edelbrock carb spacers also range in thickness from 1/2 to 1 inch.

Notes: Check out Edelbrock's divided heat insulator (PN 9266). CHP

Edelbrock Corp.

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Getting the most out of airflow and position of the carburetor is important. Moroso offers this aluminum open-wedge plate for a 4150 and 4500 mounting plate. This plate not only acts as a spacer but also tilts a front-mounted Holley carburetor as much as 5 degrees to level it on the manifold. Want something a little more mainstream? Moroso also offer an aluminum 1-inch open 4500 carburetor spacer.

Notes: Check out Moroso's carburetor adapter plate (PN 65000) in a 2-inch-thick, single-hole design. Mounts to a 4150-style intake manifold.

Moroso Performance Products


Additional Tech
Want a couple of extra ponies with out spending a lot of money? Check out this buyer's guide on carburetor spacers.
Sean Haggai Jun 1, 2009


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