Gallery: Holley’s 10-Step Procedure to Slip a Hemi into a ’73-’76 Mopar A-Body

The 1973-76 Mopar A-bodies (Dart, Dart Sport, Duster, Valiant, and Scamp) are often looked down upon by the owners of the late-60s and early-70s A-bodies. For some, that era’s “beak nose” turns them off. Still, for many, it is the fact that those years were the start of low horsepower, increased emissions regulations, and increased gas mileage requirements, which led to the manufacturers developing “sticker” package upgrades rather than actual horsepower.

Above: Hooker Blackheart and White Box offer a kit that includes the engine mounts, a transmission cross-member and urethane support, and all the mounting hardware to install a Hemi into a 1973-76 Mopar A-body.

Luckily for the fortune owners of the ’73-’76 A-bodies, Holley has not forgotten you. Holley and its multiple affiliate companies have developed a complete GEN III Hemi swap system. Like the Direction Connection catalogs of the 1970s, which included detailed “recipes” of parts necessary for performance upgrades, Holley has broken the Hemi swap into ten steps.

The first step Holley covers is fitting the engine and transmission into the chassis. Hooker Blackheart and White Box have kits to fit the Hemi into the A-body engine bay. The engine mounts bolt to the factory V8 k-member. Hooker Blackheart and White Box have transmission mounts to accommodate an A727, NAG1, or Tremec TKX 5-speed manual to the A-body. Both companies also offer a driveshaft hoop.

Above: Holley offers multiple oil pan designs to clear the k-member and fit a 5.7-, 6.1-, 6.2-, and a 6.4-liter Hemi. The pans come with a windage tray, oil pickup, O-ring, deflector, and mounting hardware.

An additional requirement to fit the Hemi into the A-bodies is an oil pan that clears the k-member. Holley has several oil pans to fit the 5.7-, 6.1-, 6.2-, and 6.4-liter engines with and without Variable Valve Timing (VVT) to meet the swapper’s needs. Also, Holley has a lower structure support, increasing the rigidity of the lower portion of the engine block. Finally, Holley has introduced a dipstick and tube to work with the Holley pans to track the oil level.

Above: Hooker Blackheart shorty headers fit within the tight confines between the Hemi and the A-body engine bay. The headers have O2 sensor provisions and an EGR passage. The mounting flanges are designed to allow ease of installation.

Once the Hemi is sitting in the engine bay, the Hemi’s factory exhaust manifolds may fit, but a better option is a pair of Hooker Blackheart shorty headers to remove the spent gasses from the engine. The headers are a stainless-steel construction, and they come fully welded, including O2 sensor bungs, and are ready to install. The headers fit around the driver- or passenger-side installed starters, the brake booster, and the factory manual steering box. If power steering is desired, the headers will work when a Borgeson steering box is installed.

Above Left: Hooker Blackheart offers several exhaust options. A cross-member back exhaust works well with vehicles that have full-length headers installed. Above Middle: If a pair of Hooker Blackheart headers are used, Hooker Blackheart has a complete exhaust system to finish the exhaust. Above Right: A pair of polished chrome tips can be added to finish the exhaust. 

When the headers are installed, adding a complete exhaust system seems reasonable. Hooker Blackheart has a designed 2.5- and 3.0-inch stainless steel exhaust for the 108- and 111-inch wheelbase Mopars. A 2.5-inch cross-member back exhaust system from Hooker Blackheart is available if a full exhaust is not needed. Hooker Blackheart offers Super Bee style exhaust tips in 2.5- and 3.0-inch sizes to add flash to any exhaust.

Holley offers several fuel pumps and tanks for the A-body Hemi. Holley EFI has two fuel pump tank modules; one pumps 255 liters per hour (lph), and the other pushes 350 lph. The fuel pressure is regulated to 58 psi. The fuel-sending unit operates with a 73-10-ohm resistance, which is compatible with a Mopar muscle-car era factory fuel gauge. On top of that, the module features a HydraMat filter, which traps debris yet ensures fuel is constantly available at the pickup.

Above Left: Holley has two fuel pump module options. One pumps 255 liters per hour (lph), and the other (shown) pushes 350 lph. Above Right: Sniper EFI has a complete tank with a 255 or 400 lph (shown) fuel pump module. The tank has a sending unit, filter, mounting screen, and installation hardware.

Sniper EFI has two pump module choices, which provide 255 lph and 400 lph. The Sniper units likewise have a new fuel tank and tank mounting straps. The Holley and the Sniper fuel pumps offer a copious fuel volume to manage even the stoutest Hemi.

The owner must choose how to pass the Hemi’s torque to the rear wheels. Will a trusty Torqueflite back the engine (A727, A904, A500, or A518), or will a manual transmission reside under the floor pan? In either case, Holley has it covered.

Above Left: Hays has several SFI-certified flexplates to attach the Hemi to the automatic transmission torque converter. Above Middle: Holley sells Tremec 5-speed manual transmissions for those that would rather handling the shifting. Above Right: Hurst has a tunnel patch to accommodate various transmissions that were never designed to fit a Mopar A-body. 

Hays offers two SFI-certified flexplates (part nos. 40-518 or 40-510) that adapt the Hemi to the Torqueflite’s torque converter. In addition, B&M has a street/strip A727 Torqueflite, which will fit the bill for those that would rather have the shifting done automatically, and, better yet, not have to cut the floor pan to locate the transmission.

For those looking to row their own, Quick Time has a bellhousing, which accommodates several Tremec TKX 5-speed manual transmissions sold through Holley. Because the floor must be modified to fit the Tremec, Hurst has a transmission tunnel patch to reshape the metal to allow the transmission to sit correctly under the floor pan.

Above: Holley and Earls have oil filter adapter kits and oil filter relocation kits to place the filter at a better location or a remote location for ease of access. 

When installing a Hemi into the tight confines of the A-body engine bay, there will likely be interference between the engine mounts and the oil filter. Holley has a 45° oil filter adapter kit, and Earls has two oil filter relocation kits (part nos. HEMI0003ERL or HEMI0004ERL). Furthermore, Holley has hardline equipment for the Borgeson power steering box if power steering is selected.

Yet another snag with the installation of the Hemi is the accessories interfere with the unibody frame rails. Holley has the Gen III Hemi Front Accessory Drive kit that relocates the alternator, belt tensioner, and air conditioning compressor. A low-mount power steering pump is positioned against the block and below the repositioned alternator. In addition, Holley has modified coolant inlet and outlet water necks.

Above: The Hemi has some accessories that could interfere with parts of the A-body engine bay. The Holley Front Accessory Drive kit relocates the accessories into a compact design, which allows the Hemi to be installed with less difficulty. 

Holley has the Terminator X and X Max, a plug-and-play Gen III Hemi engine management system for the 5.7-, 6.1-, and 6.4-liter Hemis. Depending upon the kit selected, the engine controller can operate an electronic automatic transmission and the drive-by-wire throttle body. In addition, the controllers have diagnostic light-emitting diodes (LEDs) to allow the operator to pinpoint sensors/components performing outside the programmed parameters.

Above: The Holley Terminator X and Max X are excellent engine management systems for the Hemi. Either controller can handle a stock to modified Hemi.

The Terminator X comes with boost control options, including nitrous oxide. Both controllers have a 3.5-inch hand-held touchscreen, including internal data logging, a user-designed custom gauge display, and a calibration wizard to quickly build base tunes for the Hemi.

Lastly, the final additions are ready to be added. Sniper EFI and Mr. Gasket have made valve covers for the 5.7-, 6.1-, and 6.4-liter Hemis. Earls has AN-fittings for the fuel and the supercharger intercooler to complete the engine plumbing. Finally, Flowmaster has its universal Delta Performance Air Intake that can be manipulated and cut to the owner’s needs.

Above Left: Sniper EFI and Mr. Gasket offer some flash for the Hemi. The valve covers come in a polished or black finish. Above Right: To get air into the Hemi, Flowmaster has an “assemble as needed” Delta Performance Air Intake system that can be fitted to the confines of the engine bay. 

Slipping a Hemi into an A-body has gotten much more manageable with help from Holley. Whether all nine steps parts are selected, or pieces and parts are chosen separately, know Holley has everything covered. For more information, check out Holley online or call its representatives for additional information.


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Chris Holley

Technical Contributor Chris has been a college professor for 25 years; at Pennsylvania College of Technology in Williamsport, PA. for the last 20 years. Chris instructs automotive classes in HVAC, electrical/electronics, and high-performance, including using a chassis dyno, flow benches, and various machining equipment. Recently, he added a vintage vehicle upholstery class to his teaching assignments. Chris owns a '67 Dart, a '75 Dart, a '06 Charger, and a '12 Cummins turbo diesel Ram, and he is a multi-time track champion (drag racing) with his '69 340 Dart, which he has owned for 34 years.

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