Owners manual
P/N 12621HKR
SUPER COMPETITION LS ENGINE SWAP MOUNT KIT
CHEVROLET/GMC APPLICATIONS USING CLAMSHELL STYLE MOUNTS
12621HKR (MOVES TRANSMISSION 1.25” FORWARD AND .5” UP FROM STOCK LOCATION)
Thank you for making HOOKER HEADERS your engine swap mount choice! Extensive time and research has enabled HOOKER to offer the most
options in engine swap mounts.
NOTE: This 12621HKR engine swap mount kit is designed to locate a GEN III/IV (LS Based) engine so that the transmission bellhousing is located
1.25” forward from its original position when installed with a standard small block Chevy engine using stock clamshell style mounts.
NOTE: Due to the engineered raising of the engine by .5”, the rear pinion angle may need to be modified if increased drivetrain vibration is experienced
after installation.
NOTE: Use only small block Chevy frame mounts. Big block mounts will not work.
NOTE: Worn rubber and solid isolator mounts should be replaced to ensure proper fit of the headers and other engine components that you may be
installing.
NOTE: Isolator mounts are not included in this kit, due to the variations between vehicle applications.
TIPS FOR ENGINE SWAP
1. Mark all hoses, wires, and vacuum lines, according to function. Use masking tape and a pen to achieve this.
2. Whenever possible, utilize the existing wiring and lines.
3. Get a wiring diagram of your vehicle and one for the vehicle from which the new motor was removed. Make photocopies of both systems. Add
your modifications to these copies, so you will have an accurate record.
4. The engine must be the same year or newer than the vehicle and must be from the same type of vehicle (passenger car, light-duty truck, heavy-
duty truck, etc.), based on gross vehicle weight. Failure to follow these requirements may cause you legal difficulties, especially when you try to sell
the vehicle.
5. The donor engine emission system must be reinstalled with the engine in its entirety. This includes all exhaust, crankcase and evaporative
emissions devices.
6. Save as much hardware that is removed from the vehicle as possible, you may need some items later on.
7. Do the job right; taking short cuts is not saving time, if you have to do it again. Make sure you pay close attention to critical areas like fuel systems
and brake lines. These could have life and death consequences, if ignored.
8. Do not overstress components that are designed for stock four or six cylinder torque by over-abuse with a motor of greater horsepower.
BEFORE STARTING
Your vehicle must be raised a minimum of 36 inches. A floor hoist is ideal. If no hoist is available, we strongly urge the use of axle stands as a safety
measure. CAUTION! YOUR CAR SHOULD NOT BE SUPPORTED ON A BUMPER JACK.
INSTALLATION PROCEDURE – PLEASE READ CAREFULLY
1. Disconnect the battery, remove the hood, and mark all wires, hoses, cables, lines, and linkages. Remove the engine, transmission, front motor
mounts, and transmission crossmember.
2. Bolt the plates to the engine using the flat head bolts provided and torque to factory specifications. See the Figure on page 2 for proper orientation
of mount plates.
3. Install the engine and transmission into the vehicle and slowly lower the engine onto the engine mounts. Lower the engine just enough to align the
holes in the brackets with the mating holes in the stock rubber mounts; install the long coupling bolts through both mounts. Lower the engine
completely and install the nuts onto the long coupling bolts and then fully tighten.
4. Complete the installation of all components relevant to the swapped engine.
5. Hook up all wires, hoses, cables, and linkages. Check to see that adequate clearance exists between all wires and brake lines. Check all bolts for
tightness.
When finished, give your vehicle a test drive, checking carefully for any new noises. After several days of driving, retighten all the bolts.
Any questions? Please contact Technical Service: 1-866-GOHOLLEY or 270-781-9741. For online help, please refer to the website: www.holley.com.