Hooker 1968-72 A-Body LS Swap Tech Data 1968-72 GM A-body vehicles are a popular vehicle platform on which to base an LS engine swap project. Hooker/Holley has expended considerable effort and resources (i.e. CAD modeling) to design a new system of LS swap components for these vehicles, which allow the user/installer to achieve better final geometric/performance results than has previously been possible in this LS swap application. Due to the comprehensive nature of this system of parts, the following information has been compiled as a guide to help potential users determine how they may benefit from the use of these components in achieving the goals of their G-body LS swap project. Hooker/Holley Component Data 71221006HKR- Forward position engine mounting brackets- These engine mounting brackets were designed to take advantage of the low-profile geometry of the Holley 302-2 oil pan to install an LS engine into a 68-72 A-body chassis at a lower height than is possible when using typical flat swap plates with the factory engine frame stands. The engine positioning achieved with these mounting brackets will provide your vehicle with a lower center of mass and more optimized engine inclination/ U-joint working angles than is available from any other type of mounting brackets for this application. The specific engine position provided by these engine mounting brackets and the Hooker 71222007HKR transmission crossmember allows for installation of a TH400, 2004R, 4L60-4L70 or 4L80/4L85 transmission into these vehicles without having to cut the transmission tunnel or firewall open (4L80/4L85 transmission will require dimpling of the tunnel sheet metal to provide clearance around the rear transmission cooler line and possibly the output speed sensor as well). Installation of a 4 th -gen F-body T56, or T56 Magnum transmission will require cutting/modification of the transmission tunnel and the use of the Hooker 71222007HKR transmission crossmember to achieve the optimized functional drivetrain geometry designed into the Hooker system of components. Use of these engine mounting brackets allows installation of Holley, stock Corvette and stock Vortec truck accessory drives, including the low-mount factory A/C compressor (Corvette excluded); use of the truck accessory drive requires the stock PS pump pulley to be replaced with a pulley having a maximum outer diameter of no more than 6 and the possible replacement of the rear inner bolt on top of the steering box with a low-profile button head screw. 4 th -gen F-body and GTO accessory drive systems are not installable with these engine brackets. These engine brackets provide engine positioning that is compatible with the factory A/C evaporator case and fitment of an OE automatic transmission dip stick tube. 1
71221007HKR- Rear position engine mounting brackets- These engine mounting brackets were designed to take advantage of the low-profile geometry of the Holley 302-2 oil pan to install an LS engine into a 68-72 A-body chassis at a lower height than is possible when using typical flat swap plates with the factory engine frame stands. The engine positioning achieved with these mounting brackets will provide your vehicle with a lower center of mass and more optimized engine inclination/ U-joint working angles than is available from any other type of mounting brackets for this application. The engine mounting position provided by these brackets retains the engine/transmission mating plane in the stock factory location and allows for installation of a TH350 using a stock 68-72 Chevelle crossmember only, or a TH400 or 2004R into these vehicles, using the Hooker 71222007HKR crossmember, without having to cut the transmission tunnel. Installation of a 4L60-4L70, 4L80/4L85, 4 th -gen F-body T56 or T56 Magnum transmission with these same Hooker mounting components will require extensive transmission tunnel modifications/rebuilding and frame drilling to be performed. Use of these engine mounting brackets allows installation of Holley, stock Corvette, stock Vortec truck and 4 th -gen F-body/GTO accessory drives, including the low-mount factory A/C compressor (Corvette excluded); use of the truck accessory drive requires the stock PS pump pulley to be replaced with a pulley having a maximum outer diameter of no more than 6 and the possible replacement of the rear inner bolt on top of the steering box with a low-profile button head screw. The engine positioning provided by these brackets may cause fitment issues with the factory vehicle A/C evaporator case or heater core inlet/outlet and also make the installation of an automatic transmission dip stick tube more difficult. 71222007HKR Transmission crossmember- This crossmember has been CAD designed to provide bolt-in installation of a TH400*, 2004R*, T56, T56 Magnum, 4L60-4L70* or 4L80/4L85 transmission behind any LS engine installed using the Hooker 71221006HKR or 71221007HKR engine mounting brackets only. This component has been designed to provide a strong and relatively stiff transmission mounting solution while providing dual arch passages for routing exhaust systems such as the Hooker 70501353-RHKR (2.5 ) and 70501354-RHKR (3 ) systems developed for this vehicle application. This crossmember is not compatible with convertible A-body vehicles. Installation of this crossmember requires the use of a Prothane 7-1604 poly mount or one of equivalent geometry. Installation of all mentioned automatic transmissions may require the use of an aftermarket shift cable or linkage assembly to retain proper shift indicator and/or neutral safety switch functionality. Complete Replacement of the vehicle body bushings may be required to provide adequate clearance. *Installation of a TH400, 2004R or 4L60-4L70 transmission requires the additional use of an available Hooker spacer kit, or one of equal height supplied by the user, for installed transmission geometry to be achieved as intended. 2
70201309-RHKR and 70201310-RHKR mid-length headers- These Hooker mid-length headers have been designed to provide maximum available ground clearance and are available with 1-3/4 (70201309-RHKR), or 1-7/8 (70201310-RHKR) primaries with 3 collectors. Construction details include laser cut 3/8 thick flanges, TIG welded flat-finished flanges/ports and optimized spark plug/wire clearance. In order to provide optimized wide-band O2 sensor functionality, O2 bungs are included in the adapter pipes available for these headers and not the headers themselves. Installation of these headers may require trimming of the bellhousings the older generation automatic transmissions covered in this engine swap application and will definitely require trimming to the bellhousing of 4L80/4L85 automatic transmission cases. The areas to be trimmed are in the vicinity of the bellhousing where the torque converter inspection cover is attached to it and will have no detrimental effect on the structural integrity, or functionality of the transmission. Use of an aftermarket shift cable or linkage assembly may be required to retain proper shift indicator and/or neutral safety switch functionality. Relocation of the factory brake proportioning valve may be required to install these headers, depending on the engine mounting brackets being used and which OE brake valve the vehicle is equipped with. Use a Hooker 70701311-RHKR (to 2.5 exhaust) or 70701312-RHKR (to 3 exhaust) adapter kit to provide attachment to the Hooker 70501353-RHKR (2.5 ) or 70501354-RHKR (3 ) exhaust systems. 70101318-RHKR and 70101319-RHKR long-tube headers- These Hooker long-tube headers have been designed to provide optimized ground and component clearances for this application and are available with 1-3/4 primaries/3 collectors (70101319-RHKR), or 1-7/8 primaries/3 collectors (70101318-RHKR). Construction details include laser cut 3/8 thick flanges, TIG welded flat-finished flanges/ports and optimized spark plug/wire clearance. O2 bungs are included in the collectors and indexed 12 degrees past horizontal to ensure reliable long-term wideband O2 sensor functionality. Installation of these headers may require trimming of the bellhousings of older generation automatic transmissions covered in this engine swap application and will definitely require trimming to the bellhousing of 4L80/4L85 automatic transmission cases. The areas to be trimmed are in the vicinity of the bellhousing where the torque converter inspection cover is attached to it and will have no detrimental effect on the structural integrity, or functionality of the transmission. Use of an aftermarket shift cable or linkage assembly may be required to retain proper shift indicator and/or neutral safety switch functionality. Relocation of the factory brake proportioning valve is not required to install these headers. The collectors of these headers connect directly to the Hooker 70501354-RHKR 3 A-body exhaust system. If it is desired to connect these headers to the Hooker 70501353-RHKR 2.5 A-body exhaust system, the use of a Hooker 70701314-RHKR adapter kit will be required. 3
8501HKR LS swap exhaust manifolds- Hooker LS swap cast iron manifolds have been verified to be compatible with the Hooker 71221006HKR and 71221007HKR engine mounting brackets. A Hooker 70701311-RHKR adapter kit may be used to connect these manifolds directly to the Hooker 70501353-RHKR 2.5 A-body exhaust system; O2 bungs are included in each adapter tube. 70501353-RHKR and 70501354-RHKR Exhaust Systems- These exhaust systems have been designed for direct bolt-in connection to Hooker A-body long-tube headers and for connection to Hooker A-body mid-length headers through the use of a Hooker 70701311-RHKR (to 2.5 exhaust) or 70701312-RHKR (to 3 exhaust) adapter kit. Key design features of these exhaust systems include optimized ground clearance, the ability to accommodate up to a 3.5 diameter drive shaft and compatibility with DSE, Hotchkis and Hellwig brand rear suspension anti-sway bars. Installation of these systems requires the use of a Hooker 71222007HKR transmission crossmember, or a stock 1968-72 Chevelle crossmember, installed with 3/8 spacers under each end, to provide the required clearance under the crossmember. Vehicle Variances As the frames of 2 door hardtop and convertible model A-bodies are different, the Hooker 71222007HKR transmission crossmember will only install in hardtop models There are two known OE brake proportioning valves that were factory installed on the inside of the driver s side frame rail; the Hooker mid-length headers may not be compatible with both of them and may require relocation of the brake valve. Vehicle Component Compatibility Transmission and shift linkage- 4L80/4L85 transmissions represent the worst-case scenario for providing suitable shifter cable/linkage connections due to the location of the shift selector shaft, which is positioned 2-1/4 further rearward than that of the other GM automatics; a fore/aft selector shaft position that deviates by no more than ½ is used on the other GM automatics. Use of an aftermarket (Lokar or similar) cable or shift linkage assembly may be required to provide proper gear selector and/or shift indicator and neutral safety switch functionality on all installations. 4
Steering boxes- The Hooker 1968-72 A-body swap components have been validated for compatibility with the OE Saginaw 700 series power steering box only. Compatibility with any other type of steering box is unknown. Air conditioning- The Hooker A-body engine mounting brackets are designed to provide the ability to install the OE truck, F-body or GTO A/C compressors into you re a-body vehicle; notching the vehicle frame rail maybe required in certain applications to provide clearance for the hoses/fittings. Holley 20-134 and 20-140 A/C compressor mounting brackets can also be utilized to provide an OE appearing high-mount compressor installation on the passenger side cylinder head. OE LS Engine Component Compatibility The design geometry of the Hooker headers and engine mounting brackets provide installation compatibility of the following stock OE LS engine components in an A-body swap vehicle. Intake manifold (truck, LS1, LS2, LS3 and LS6) Valve covers Ignition coils and brackets Spark plug wires Starter motor Gen IV block mounted knock sensors Oil cooler lines Holley LS Engine Component Compatibility A multitude of LS engine performance and appearance upgrade products are available from the Holley family of brands, which enable the user to achieve their G-body LS swap project goals. Included in this list of components are: Holley carburetors, EFI systems, fuel pumps/regulators, injectors, ignition coils, valve covers and A/C compressor brackets Weiand Intake manifolds Earl s plumbing fittings/hoses NOS nitrous oxide kits 5