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Installation Instructions for 15400 to 15404 & 15412 Throttle Body Spacer

for 1986 to 1995 Chevy & GMC 2.8L, 4.3L V6, 5.0L, 5.7L & 7.4L V8 Trucks, Blazers, Suburban’s, & Cars equipped with Throttle Body Injection. 

Installation Instructions: 

Note: Read all instructions before installing this kit. Basic automotive skills are required for proper installation. The kit, in most cases, takes approximately an hour to install. If any instructions are not clear, take the kit to a certified repair shop to be installed. 


1. Leave key in the off position. DO NOT turn the key to the RUN position until the installation is complete. 

2. Remove the air cleaner and spacer from the TBI (Throttle Body Injection) unit. 

3. Mark and remove all the vacuum lines. Remove all electrical connections and linkages. 

4. Remove the gas lines from the rear of the TBI unit. CAUTION: There may be pressure remaining in the fuel lines. Wear safety glasses to protect your eyes. 

5. Remove the TBI mounting bolts and pull the TBI unit from the intake. Clean any old gasket material off both surfaces. To avoid engine damage, be careful not to drop anything down into the intake manifold. 


1. Install the new gasket onto the intake manifold and then the TBI Spacer Plate followed by another gasket and finally the TBI unit. Use the longer bolts and washers, included in the kit, and bolt down the TBI unit (for 1992 to 1995, use the 2 larger head bolts for the rear mounting holes. The air cleaner rods screw into the TBI unit). Tighten the bolts to 12ft-lbs of torque. 

2. Install all the vacuum lines and electrical connections. Reconnect the throttle linkage and lock in place with the clip (on some models, if the throttle linkage does not reach, loosen up the throttle bracket from the intake and slide it forward. Hold the linkage in place and retighten). Reconnect the transmission kick down, if equipped. IMPORTANT: On 700R4 Auto: adjust the cable by pushing in the lock tab with a screw driver. The tab is found on the backside of the throttle bracket. Hold in the tab and push the plastic pintail inward until it stops. With the engine off, press the gas pedal to the floor. The action will adjust the cable. Work the gas pedal several times to be assured that it works properly. 

3. Reinstall the gas lines. IMPORTANT: take care not to cut the O-rings on the end of the lines. If the lines do not reach, remove the line bracket on the transmission bell housing and pull the lines up. Reinstall the bracket. 

4. Cycle the key to the RUN position several times, for 5 seconds each time. Check for leaks. If no leaks are evident, start the engine and check again for any leaks. 

5. Idle the engine for approximately 5 minutes to allow the computer to readjust the idle speed. 

6. Turn off the engine and install the air cleaner and spacer ring. The installation is complete. 

NOTE: The onboard computer utilizes adaptive memory. The performance characteristics of your vehicle may change after several hours as the computer relearns and enhances fuel delivery.

California CARB, Exemption D-623

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Posted on
May 10, 2018
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