DO I NEED A CARBURETOR ADAPTER OR SPACER?
A carburetor can be either Square-Bore or Spread Bore. An intake manifold can also be either Square-Bore or Spread Bore. All you have to do is match the carburetor flange to the manifold flange. Sometimes even if your carburetor and manifold have the same bore shape, the manifold flange isn't large enough so an adapter is still recommended.
ALL EDELBROCK PERFORMER AND THUNDER SERIES CARBURETORS ARE SQUARE-BORE
MOST EDELBROCK INTAKE MANIFOLDS ARE SPREAD-BORE
Since either of the 2731 and 2732 adapters are only 0.1” thick, it won’t add any significant amount of height if you are worried about hood clearance. The 2696 is intended for Quadrajet and Thermo-Quad intakes, but since it has 4-holes, some people use it as an aluminum 4-hole spacer. The 2696 is 0.850" thick, so it does add some height.
BEFORE YOU BUY AN ADAPTER, READ THIS!
If you need an adapter, there are better options than just buying an adapter. The adapters come with a base gasket. Over time, these gaskets may need to be replaced. You can buy reusable base gaskets which cost more. There is still a better solution.
There are Heat Insulating Gaskets which are made from a rigid nitrile rubber. These gaskets are so rigid, that when they are installed, an adapter is no longer needed. You also don’t need to use base gaskets anymore since THESE ARE REUSABLE GASKETS!
There are Heat Insulating Gaskets which are made from a rigid nitrile rubber. These gaskets are so rigid, that when they are installed, an adapter is no longer needed. You also don’t need to use base gaskets anymore since THESE ARE REUSABLE GASKETS!
NO MORE ADAPTERS. NO MORE BASE GASKETS, ADDED HEAT ISOLATION
Either of these Heat Insulator Gaskets are only 0.320” think, and only add a small amount of height if you are worried about hood clearance. For Edelbrock divided dual-plane manifolds, use 9266.
IF YOU HAVE AN EDELBROCK RPM AIR GAP - YOU SHOULD USE AN OPEN SPACER
Even though the RPM Air Gap is a dual-plane intake manifold, a divided spacer can cause some power loses because the divider will cover the cutout in the plenum wall. If you don't want to block that cutout, use an open-center spacer. Watch the video below to see the dyno results for yourself.
WHAT DO SPACERS DO?
Spacers are added for a variety of reasons so there are a variety of spacers to chose from. Adding a spacer can help with mixing air and fuel, carburetor heat soak, and compensating for an undersized manifold.
Better Mixing = Taller Spacer
Undersized Manifold = Taller Spacer
Carburetor Heat Soak = Wood Fiber Laminate
Undersized Manifold = Taller Spacer
Carburetor Heat Soak = Wood Fiber Laminate
IS THERE ENOUGH HOOD CLEARANCE FOR A SPACER?
First look at the height of your air cleaner and close the hood. If you have plenty of room between the top of the air cleaner and the hood, then you can add a spacer. If hood clearance is a problem, you can install a drop-base air cleaner that will lower the overall height of the air cleaner assembly which might give you some room to squeeze a spacer into.
SO WHAT SPACER SHOULD I USE?
If you have plenty of room and you are adding a spacer, you have to figure out what spacer is right for your application. There are choices depending on what material, height, and hole pattern.
Materials
Aluminum Wood – Heat Isolation Phenolic (Plastic) |
Hole Pattern
Open Center – Intake manifold is undersized (Adds Plenum Volume) Divided Center – Matches Intake on Divided Dual-Plane Manifolds 4-Hole – Enhances Throttle Response and Low RPM Torque |
Height
½” ¾” 1” 2” |
If you know the reason(s) why you are adding a spacer and how much hood clearance you have, it shouldn’t be too hard to choose a configuration. There are endless dyno tests, opinions, and theories about carburetor spacers. If you really have a feel for your vehicle, there will be a noticeable difference between open and 4-hole spacers. Adding a spacer may require you to readjust or recalibrate your carburetor.
EDELBROCK SPACERS BY TYPE
WOOD FIBER LAMINATE
PART NUMBER8719
8720 8722 8723 8724 8725 8726 |
HEIGHT3/4"
1" 1/2" 1/2" 1/2" 1/2" 3/4" |
HOLE CONFIGURATIONOpen
Open Divided 4-Hole Open Divided 4-Hole (Q-Jet) |
ALUMINUM
PART NUMBER8714
8715 |
HEIGHT1"
1/2" |
HOLE CONFIGURATIONDivided
Divided |
PHENOLIC
PART NUMBER8710
8711 8712 8713 |
HEIGHT1"
1" 2" 2" |
HOLE CONFIGURATIONOpen
4-Hole Open 4-Hole |