Owners manual

ManualsBrandsHooker Headers ManualsAutomotive2451-1HKR Super Competition Long Tube Header

2451HKR (black paint), 2451-1HKR (silver ceramic), 2451-2HKR (stainless),

2451-3HKR (Darkside black ceramic), and 2451-4HKR (Titanium)

Competition Header 265-400 Chevy Engine

Instruction Sheet

WARNING! Breaking in an engine with ceramic-coated headers WILL result in damage to the coating and will VOID all warranties.

Ceramic-coated headers require several heat cycles to fully cure before they will withstand extreme heat. Hooker®

recommends using cast iron exhaust manifolds or old headers to break in new engines to avoid coating damage.

Please call tech service at 270-781-9741 for additional information regarding ceramic-coated exhaust products.

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 prior to installing headers, take the time to make a careful and complete

inspection of both engine and transmission mounts. Replace them if they look worn or damaged, otherwise this may affect the

header fitting into your vehicle properly.

HEADER INSTALLATION PROCEDURE/ DISASSEMBLY & ASSEMBLY INSTRUCTIONS

PLEASE READ THOROUGHLY & CAREFULLY

LEFT SIDE

1. Disconnect the battery cable to prevent damage to the electrical systems.

2. Unbolt the headpipe from the stock cast iron manifold and push aside.

3. Remove the spark plugs, alternator, clutch linkage, oil filter, dipstick tube, and (on late model cars) unbolt the power steering bracket. 1976

models may not require oil filter position.

4. Starting from below, work the header up through the chassis into position.

NOTE: On some year models, it will be necessary to remove the two struts that bolt to the sub-frame. See illustration A.

5. Place the gasket into position and start all bolts (the most restricted first).

NOTE: If equipped with a smog air comp (connect to manifold at head), remove the injection tubes from the stock exhaust manifold and install

them in the bushings on the headers. See illustration B.

6. Replace the clutch linkage, oil filter, dipstick tube, alternator, and spark plugs. On late model cars with power steering, use the spacer

provided in the accessory package and the long bolt from the stock exhaust manifold to remount the power steering. See illustration C.

NOTE: A) Early models will require conversion screw-on type oil filter.

B) Modify the clutch linkage as shown in illustration D.

C) Models with generator/alternator on the left side must purchase Hooker bracket P/N (10928HKR). See illustration E.

D) If the header is equipped with bushings for smog injection tubes, the bracket must be notched to clear the bushings. See

illustration F. If the stock exhaust manifold had less than 4 smog injection tubes, any unused smog bushings on your headers

must be plugged. Use 1/4” pipe plugs or 1/2”-18 bolts or weld a cap over the bushing(s). See illustration B.

RIGHT SIDE

1. Remove the spark plugs, stock exhaust manifold, and starter. On cars equipped with air conditioning, unbolt the compressor and lay aside.

Some year models may not require starter removal.

NOTE: Some models may require the floor board heat shield removal for adequate header clearance.

2. Starting from below, work the header up through the chassis into position. Some year models may require the engine to be raised straight

slightly (use a board between the pan and jack).

3. Place the gasket into position and start all the bolts (most restricted first).

NOTE: If equipped with a smog air comp (connect to manifold at head), remove the injection tubes from the stock exhaust manifold and install

them in the bushings on the headers. See illustration B.

4. Replace the starter and connect the wires. Reroute the wires as needed for clearance.

5. Tighten all bolts evenly and replace the spark plugs.

6. To connect the collector to your stock exhaust system, purchase the Hooker reducer kit P/N 11030HKR. Position the gasket and the bolt

the reducer to the collector. Cut the head pipe to the correct length and weld the reducer.

Summary of content (4 pages)

PAGE 1
2451HKR (black paint), 2451-1HKR (silver ceramic), 2451-2HKR (stainless), 2451-3HKR (Darkside black ceramic), and 2451-4HKR (Titanium) Competition Header 265-400 Chevy Engine Instruction Sheet WARNING! Breaking in an engine with ceramic-coated headers WILL result in damage to the coating and will VOID all warranties. Ceramic-coated headers require several heat cycles to fully cure before they will withstand extreme heat.
PAGE 2
NOTE: Finish the performance job your headers started by adding a Hooker competition dual exhaust system. Large 2 1/4” diameter tubing is mandrel bent, not press bent. Mandrel bending maintains a consistent inside diameter form maximum flow; press bending will crush the pipe, easily reducing volume by more than 10%. Our dual exhaust system is perfect when used in conjunction with Hooker Super Competition Turbo 21105HKR or Hooker Competition Turbo 21005HKR. Purchase duel exhaust no.
PAGE 3
Gen/Alt bracket 10928HKR (purchase not required on all models) Gen/Alt bracket 10927HKR 3/8” bolt, washer, and locknut (2 ea. required) 1” long header bolts (2 required) Illustration E Trim as required to clear smog bushing Illustration F 3/4” O.D. tubing Drill hole in collector. Optional tube shape Weld into collector around tube pipe.
PAGE 4
LIMITATION OF LIABILITY – DISCLAIMER The regulation of emissions production, noise levels, and safety standards is undertaken by the federal government, each of the fifty state legislatures, and by many local municipalities, towns, and counties.