Extrudabody Throttle Control Explained

Overview

Throttle Plates in Extrudabody ITBs are designed to be controlled by throttle cables using our version of a cam-style system.  Our Throttle Cams and Throttle Stops are designed to function together and are highly flexible like all Extrudabody designs.

The Cam and Stop come assembled but you can easily dismantle them and change the orientation to best connect to your throttle cable. As you can see from the picture on the right, our cable mounting hardware allows the cable to control the Cam from above or below.  It also can be placed on the left side to suit your application.  And, multiple Cams can be connected in push/pull configuration, such as for V6 and V8 multi-bank control.

Download and watch a short video on our throttle system here (13meg download in WMV format)

If your current car has the throttle pedal controlling a rod and pivot system, you may need to adapt your pedal to a cable system.  Please see our article on Throttle Pedal Conversion. 

If your car already uses a throttle cable, installation is often as simple as cutting to length and using the right throttle bushing/barrel in our Throttle Cam.  We also offer throttle cables and accessories and can build a cable to length to your specifications.

Note that the Cam mounts on the left side of our ITBs only (when looking down on the fuel injector hole with the injector firing away from you). 
 
Throttle Stop

 

 Throttle Cam
   
Throttle LeverThrottle Lever
Our Throttle Lever provides an additional solution for adding spring returns.  By default, our ITBs include a return spring integrated with the Throttle Cam and Throttle Stop system.  The Throttle Lever can be connected to a commonly available carb return spring.  This allows you to fine tune your throttle pedal feel, and creates a backup spring return should one spring fail.  Always use at least 2 return springs with any ITB system.

Levers are also handy for creating cross-manifold linkages or tying in to Weber-style rod linkage systems.

Su Interconnect


Cross Connect
Throttle Cable Holder

Throttle Cable Holder hardware (pictured below on left) also holds true to the Extrudabody Design to be universal in Nature. It has a ¼-20 slot that is counter sunk to help hide the Allen Head Cap Screw and has 2 6mm holes Tapped that hold Straight, 135, and 90 degree Chrome Plated Cable guides with built in cable Adjustment. The ¼-20 is slotted for adjustability to be used with or without a positive stop. The cable strut and cam can be used in Push/Pull applications where multi-bank ITB’s are used or for other auxiliary pulled devices. The Cable Holder can also be mounted below or above the Throttle Cam.

 
Throttle Return Springs

You must make sure your assembled ITB system has very smooth throttle operation and robust throttle return to fully closed position.  Extrudabody kits include a single Return Spring (as pictured below, situated between the Throttle Stop and ITB), but this may or may not be enough to overcome the resistance of your throttle pedal setup.  Also, each ITB adds some resistance to throttle movement and a slightly warped intake manifold adds even more resistance.  Only you will be able to test your system and make one of the following choices:

  • Add one or more Return Springs in additional ITBs
  • Add an external Return Spring connected to the Throttle Cam and your engine

  • Add a Throttle Lever (available from Extrudabody) and an external Return Spring

In any case, you need to use multiple Return Springs even if your kit seems to operate fine with the single standard spring.  External return springs are generally the best option because they offer fairly constant pressure and are available in a wide variety of sizes and strengths.  Any auto parts store will have a carburetor return spring kit with 2 or 3 types of springs so you can optimize the pedal feel.  These springs must be secured to your engine or firewall.

  

Throttle Cables

Extrudabody offers a full set of throttle cables and accessories, such as 90 degree bends.   To order cables, it's best to call or email us with your requirements.  If you choose to order our Throttle Cable and cut them to length yourself, instructions are below.

 

 

 

Overview of Throttle Cable Components:

Throttle Cable Assembly

Suggested Tools:

  1. Die Grinder

  2. Bearing Grease

  3. Terminal Crimpers

Procedure:

Step 1: Wrap the Casing of the Inner Cable with Tape before cutting. Cutting through the tape will keep the ends of each part from fraying.

Step 2: Use a Die Grinder to cut the Casing or Inner Cable and cut through the tape as well.  Take your time, the die grinder keeps the Casing and the inner Cable from being crushed which happens often with cutters or other type of cutting means.

Step 3:  Once you cut the Outer Casing you may have to use a 1.5mm Allen Wrench to restore the INNER Casing liner to it’s open state, sometimes the heat from grinding the Case fuses the liner and it has to be opened!

 Step 4:  Thread the cable and assemble to your specifications or as shown below.   When using Adjusters, use a small amount of Heavy Bearing Grease in the end of the Straight adjuster and 90-Degree Adjuster where the Ferrell inserts.  This will help lubricate and seal the Cable from Moisture.