Holley 502-3 Installation & Adjustment Instructions

P/N 502-3 (1985 1/2 – 89 GM Truck 2.8L V-6 Engine) 400 CFM
P/N 502-4 (1986 – 89 GM Truck 4.3L V-6 Engine) 670 CFM
P/ N 502-5 (1987 – 89 GM Truck 5.0L V-8 Engine) 670 CFM
P/N 502-6 (1987 – 89 GM Truck 5.7L V-8 Engine) 670 CFM
P/N 502-7 (1988 – 91 "S" & "T" Trucks 4.3L V-6 Engine) 670 CFM
Installation & ADJUSTMENT INSTRUCTIONS

INTRODUCTION

Congratulations on your purchase of a Holley throttle body! Holley Performance Products has written this manual for the
installation of the Holley throttle body. Please read all the WARNINGS and NOTES. They contain valuable information that
can save you time and money. Should you need information or parts assistance, please do not return the unit to the store
without first contacting technical service at 1-270-781-9741, Monday - Friday, 7 a.m. to 5 p.m. CST. By using this number, you
may obtain any information and/or parts assistance that you may require. Please have the part number on hand of the product
you purchased when you call technical service.
WARNING! To preserve the warranty, instructions must be read and followed thoroughly and completely, before and
during installation.
NOTE: Holley Performance Products cannot and will not be responsible for any alleged or actual engine or other damage or
other conditions resulting from misapplication of the throttle body described.
NOTE: Prior to and after installing your new throttle body, manually operate the throttle lever to check for binding or other
malfunction. Also, make a visual inspection of the throttle body, to look for bent levers, etc., or any other shipping
damage.

REMOVAL

1. Remove the fuse marked "fuel pump" from the fuse block. Start the engine and allow it to run until the fuel supply remaining
in the lines is consumed. When the engine stalls, engage the starter for three seconds to ensure all the pressure is
relieved. DO NOT turn the key to the "RUN" position until the installation is complete.
2. Remove the air cleaner. Remove the air cleaner spacer from the top of the throttle body. This spacer will be used on the
new throttle body.
3. Mark and remove the remaining vacuum lines from the throttle body. Remove all the electrical connections from the TBI.
THROTTLE BODY