HOOKER 520-8527-3HKR Headers Exhaust Manifolds Instruction Manual
- June 3, 2024
- HOOKER
Table of Contents
520-8527-3HKR Headers Exhaust Manifolds
Instruction Manual
520-8527-3HKR Headers Exhaust Manifolds
Thank you for making HOOKER™ HEADERS your choice in high-performance exhaust
system components.
These Hooker™ cast exhaust manifolds have been designed to fit into a wide
variety of replacement and engine-swap applications, with final outlet
connections to be fabricated by the installer. The design of the manifold
passages and the position of the exit flange provides excellent performance in
street/performance applications. However, this product does not have a
C.A.R.B. Executive Order Exemption and therefore may or may not be legal for
any particular pollution-controlled application.
The casting is of High-Silicon-Moly ductile iron material and will provide
trouble-free service for street/performance small-block Chevrolet engines. The
nickel-plated steel mating flanges that have been included with these
manifolds are intended to be utilized “as needed” to satisfy your particular
installation requirements; their featured geometric dimensions will assist in
the fabrication of a tightly-quartered connection between the manifolds and
your exhaust system. A single 2.5” x 2.5” radius U-bend (not included) can
usually provide sufficient bend material to route the exhaust around any
close-proximity components such as lower control arm frame perches. Once clear
of these obstructions, transition to larger tube diameter, if desired, can
easily be accomplished by expanding the 2.5” tubing with a pipe expander, or
welding on a tapered transition.
WARNING! Breaking in an engine with ceramic-coated versions of these
manifolds will most likely result in damage to the coating and VOID all
warranties providing coverage to it. HOOKER™ recommends using bare cast-iron
manifolds or an old set of headers to break in engines to avoid coating
damage.
Ceramic-coated manifolds require several heat cycles to fully cure before they
will withstand extreme heat, so care should be taken to provide a series of 4
to 5 intermittent heat cycles to “set” the coating prior to putting the
vehicle into service. An incremental increase in run duration and throttle
angle should be added to each successive cycle; initial and final run
durations between approximately 1 and 7 minutes will be sufficient to set the
coating.
CAUTION! When working under your car, be sure to properly support it with
jack stands or ensure the locks on your vehicle lift are engaged if using one.
NEVER WORK UNDER A CAR SUPPORTED BY A BUMPER JACK OR HYDRAULIC LIFTING JACK!
INSTALLATION PROCEDURE
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Disconnect the negative battery cable.
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Remove spark plug wires.
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Remove spark plugs, if it appears necessary to be able to remove existing manifolds/headers from the vehicle.
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Remove the engine oil dipstick tube from the passenger’s side of the engine.
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Disconnect any exhaust components connected to the outlet of existing manifolds/headers.
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Remove the existing manifolds/headers from the engine.
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If an entirely new exhaust system will be constructed to attach to your Hooker™ manifolds, remove all existing exhaust components.
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If adapting your Hooker™ manifolds to connect to an existing exhaust system, choose a convenient interface connection point and cut and/or remove all exhaust componentry forward of that point and dress all joints for proper welding execution, as needed. An example of this step is shown in the photo shown on the next page. The Hooker manifolds being installed on this sample application will be connected to the existing converter pipes. The chosen interface connection point was at the inlet of the converter so the pipe coming from the existing manifold was cut here as indicated by the arrow.
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Install the Hooker™ cast iron manifolds to the engine. Use the provided gaskets or your preferred brand of exhaust gaskets when installing the manifolds
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Temporarily attach the included flanges to the outlets of the manifolds with the four included 10mm x 1.5 bolts to determine the appropriate amount of U-bend or straight pipe to use for the first pieces of the outlets coming off the manifolds.
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Use a marking pen and place an index mark on the flanges and tube sections to indicate any specific rotation, as shown in the left photo below. Once satisfied with the marked position, remove the parts from the vehicle for welding.
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On the welding bench, line up the index marks on the parts and place a minimum of three tack welds around the circumference of the flange, as shown in the right photo above.
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Deposit a continuous weld around the flange while observing the following guidelines:
• The connecting weld bead can be deposited as a fillet around the exterior of the flange, or around the I.D. of the face of the flange for a cleaner appearance. For welding these flanges to mild/low carbon steel pipe, ER70S-2 filler rod is recommended. If welding to 409 or 304 stainless steel pipe, 309 filler rod is recommended. -
Reattach the flange assemblies to the manifold outlets and complete the mock-up of the adapters to the existing exhaust or a complete exhaust system before removing for final welding. Be sure to mark the location of O2 bungs, if needed. The photos below depict the final parts fabricated from U-bends to connect the Hooker™ manifolds to the existing converters in the sample application.
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Install the finished welded parts into the vehicle for the final time and fully tighten all fasteners.
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Reinstall the engine oil dipstick tube and spark plug wires/spark plugs.
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Reconnect the negative battery cable to the battery.
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Start the vehicle and check for leaks. If installed manifolds are ceramic coated, perform the coating set thermal cycling procedure recommended previously in this document.
Hooker Technical Support
1-866-464-6553
1-866
199R11962
Revision Date: 4-24-20