Why The 1970-1974 Mopar E-Body Is A Great Gen III Hemi Swap Candidate

07/28/2021
10 min read

Why The 1970-1974 Mopar E-Body Is A Great Gen III Hemi Swap Candidate

07/28/2021
10 min read

Holley has made great strides in making Gen III Hemi power accessible to the masses. They have engineered swap kits for 1966-72 B-bodies, allowing such iconic muscle car names as Charger, Road Runner and Coronet R/T to be converted easily to late-model, fuel-injected power that is on-par with the legendary powerplants of the 1960s. They have engineered swap kits for the 1987-1996 and 1997-2004 Dodge Dakota, as well as the 1972-1993 Dodge D-series pickup that will put the "haul" into your hauler. They've even figured out how to shove a Hemi into your YJ or TJ-era Jeep Wrangler. But with their latest Gen III Hemi swap kit, Holley and Hooker BlackHeart are going after the kings of the Mopar hill: the 1970-1974 Dodge Challenger and Plymouth Barracuda.


The Mopar E-bodies have had a legend about them from the moment they hit the ground running in late 1969 as 1970 models. While they were both full models, complete with six-cylinder and low-power small-block V8 options, the cars that imprinted on everybody's mind are the hot small-block Trans-Am homologation specials, the big-block cars that would haze tires on command, and the mythical Hemi-powered machines that were only just barely removed from the Pro Stock monsters that drag teams like Sox and Martin used in battle at drag strips across the nation. Restoration fans have been after them for decades and some of the most expensive muscle cars to ever hit the auction block are either a Dodge Challenger or Plymouth Barracuda.


1974 Plymouth 'Cuda


But for every Hemi or 440 six-barrel or 340 Six Pack, there were thousands of Slant Six or 318-powered cars that were sold as basic machines. Nothing against the bulletproof Six or the yeoman 318, but they just can't live up to the power and the reliability of the Gen III Hemi. Whether you go wild with the High-Impact paint colors and stripes or keep one low-key and sinister, an E-body's muscular profile promises a throwback to the wild, gear-grabbing days gone by. Every inch of a Challenger or Barracuda screams muscle, and the horsepower of modern-day Mopar mills will blow the engines of the "good old days" out of the water...even the vaunted 426 Hemi. Let Holley help you put even more muscle into the ultimate Mopar muscle car.

1970-1974 Mopar E-Body Gen III Hemi Swap Parts Available

PartPart Number
Hooker BlackHeart Engine Mount Brackets, Gen III Hemi Swap, 1970-74 Challenger/Barracuda (with V8 K-Member)BHS566
Hooker BlackHeart Transmission Crossmember, Gen III Hemi Swap, 1970-74 Challenger/Barracuda BHS567
Hooker BlackHeart A727 Transmission Adapter Plate, 1970-74 Challenger/BarracudaBHS568
Hooker BlackHeart NAG1 Transmission Adapter Plate, 1970-74 Challenger/BarracudaBHS569
Hooker BlackHeart 8HP70 Transmission Adapter Plate, 1970-74 Challenger/BarracudaBHS570
Hooker BlackHeart 8HP90 Transmission Adapter Plate, 1970-74 Challenger/BarracudaBHS591
Hooker BlackHeart Gen III Hemi Swap Long-Tube Headers, 1966-74 Mopar B/E BodyBHS2358
Hooker BlackHeart 3.0" 304 Stainless Steel Exhaust with Polished Stainless Steel R/T-style Tips, ChallengerBH23316
Holley Gen III Hemi Swap Oil Pan - Mid-Sump Non-VVT Engines, Aluminum302-60
Holley Gen III Hemi Swap Oil Pan - Mid-Sump VVT Engines, Aluminum302-61
Weiand Gen III Hemi Swap Oil Pan - Mid-Sump Non-VVT Engines, Steel5050WND
Weiand Gen III Hemi Swap Oil Pan - Mid-Sump VVT Engines, Steel5051WND
Holley Power Steering Kit For Gen III Hemi Swaps - 2014-current Car Belt Spacing, Low Pressure97-382
Holley Power Steering Kit For Gen III Hemi Swaps - Pre-2013 Car Belt Spacing, Low PressureVK090244
B&M NAG1 Pro Stick Swap Shifter, NAG1, With Center Console81188
Holley EFI Terminator X Max, Gen III Hemi 2013-Current, with DBW Throttle Control550-1424
Holley EFI Gen III Hemi VVT and SRV Harness558-132
Frostbite Aluminum Radiator, 4-Row, 1968-1974 Mopar B- and E-Body Gen III Hemi SwapFB701
Frostbite High Performance Fan/Shroud Package (FB225 and FB227 Radiators)FB529H
Holley Sniper EFI Fuel Tank System, 1970-74 Dodge Challenger, 255 LPH19-137
Holley Sniper EFI Fuel Tank System, 1970-74 Plymouth Barracuda/'Cuda, 255 LPH19-136
Holley EFI Hi-Flow Billet Fuel Rails For Gen III Hemi 534-284
Hays Steel SFI Certified Flexplate, Mopar Gen III Hemi to NAG1, 8HP70, 8HP9040-510
Hays Steel SFI Certified Flexplate, Mopar Gen III Hemi to A727 (36RH/37RH), A904 (30RH), A500, A518 (46RH/46RE)40-518
Hooker BlackHeart Tremec TKX Transmission Adapter PlateBHS592
Hooker BlackHeart Battery Relocation TrayBHS589
Hooker BlackHeart Power Steering Remote Reservoir BracketBHS590

History of the Chrysler E-Body


The first two generations of Plymouth Barracuda, which had been introduced in 1964 and had been updated for 1967, had proved that the A-body platform could be sporty and perform well...but it also proved that the platform was not happy with big-block power. Big-block Barracudas wound up with restrictive exhaust manifolds that choked the 383 down from 325 horsepower to 280 horsepower, and both power steering and air conditioning could not be optioned. And don't ask what the 440 and the Hemi would do the entire body structure the first time that you would bury your right foot into the loud pedal. That was fine for the hard-core power crowd and for the legitimate professional racers, but was not going to be acceptable for the regular buyer, and the heads of Chrysler knew that. So, for 1970, the Barracuda would move to the new E-body, where it would be joined by a new Dodge twin, the Challenger. The main goal of the E-body was to handle any engine that Chrysler had on the shelf at the time by using the radiator support, engine box, cowl, firewall and dash structure from the 1971 B-body (Satellite/Coronet) cars. Anything from the thrifty Slant Six to the all-conquering 440 and 426 Hemi big-blocks would fit with ease. No more struggling to change spark plugs. No more sweating it out because air conditioning wasn't available. No more lack of an answer to big-block Mustangs, Cougars, Firebirds, Camaros or Javelins. Throughout the four-year run, just over 300,000 of these pony cars were made, and while there were plenty of pedestrian models offered up between 1970 and 1974 from both divisions, it's the performance models that have kept the Dodge Challenger and Plymouth Barracuda high on the list of dream machines from the Musclecar Era.



Whether you grew up with these cars, saw one at a show, remembered them from dragstrip summers gone by or were influenced by the many different celebrity cars that Hollywood made popular (like the white 1970 RT/SE Challenger that Kowalski drove in Vanishing Point or the yellow Hemi 'Cuda convertible that was the rolling star of the television show Nash Bridges), a performance E-body just makes sense. You can cruise it if you want or you can let it all hang out in a tire-smoking fashion that will alert the nearest friendly officer...that's up to you. And there are many ways to get that performance. Chrysler saw fit to equip E-bodies with the Hemi, the six-barrel 440, and the 340 six-barrel into both cars, along with other big-block and small block V8 offerings. And if you have one of those number-matching big-blocks, we understand why you'd want to keep that. But maybe you found a long-forgotten 318-powered car somewhere and you want to give it the kick that it certainly didn't have back in the day. Why not consider the benefits of swapping it over to a Gen III Hemi? Not only will you get the performance that will be on-par or better than the wilder offerings from 1970, but you open up the door to fuel injection, more forward gears for better fuel economy, and a plethora of parts at your disposal. Don't think it's worth the hassle? Follow along...

Why Swap To A Gen III Hemi?


Chrysler 5.7 Hemi Cutaway Drawing

Artist: David Kimble


The horsepower numbers that the 1970-71 Challenger and 'Cuda put up are the stuff of legends, numbers that fans can quote at the drop of a hat. The claimed 290 horsepower and 345 lb-ft. of torque from the 340 cubic inch engine that lived in the one-year-only Plymouth 'Cuda AAR and Dodge Challenger T/A homologation specials was almost laughable, since the car was pulling quarter-mile times that were hot on the heels of the 383, 440 and Hemi models. Name your poison: did you want a set-up handler with all of the suspension goodies, staggered rubber in some of the larger sizes available, or did you want the all-conquering quarter-mile monster that was just as content to rip the rear skins off of the rear wheels as it would be to rip the car in the other lane a new one? If the 340 Six Pack was underrated, the Hemi was ridiculously underscored. The 425 horsepower/490 ft-lb. of torque figure would do wonderful things when connected to highway friendly gears, and if you optioned in a deeper gear set, the personality change was from wild to wicked.



But let's remember, before we get too carried away into nostalgia, that not every Challenger or Barracuda was a street-terror that would stripe the road the second you breathed at the pedal. Less than 3/10ths of a percent of the total production run were Hemi cars. The big-blocks would disappear after 1971, as well as the multi-carbureted 340. And in 1974, the 340 itself went away, yielding the big-engine slot to the 360ci small-block. The one problem with the E-body twins was their timing: they were late to the horsepower party and didn't fare the onset of smog controls and government intervention well. Bumpers grew big bumperettes to handle the new 5-MPH impact regulations. Graphics and colors were toned down. And ultimately, even though you can see hints of where a second generation could have headed with the Dodge Diamante concept car and the photos of factory body developments of the 1975 Plymouth Barracuda that were released a few years ago, there was no saving the E-body. Chrysler's financial woes and a market shift towards personal luxury cars slammed the final nail in the coffin home, and only a handful of attempts were made at bringing V8 Mopar power back into the fold afterwards. The 1978-79 Dodge L'il Red Express pickup, the 440-powered Mopar police cars, the Aspen Super Coupe/Petty Kit Car and the Mexican-market 1982 Dodge Magnum 360 tried, but ultimately Chrysler made the switch to front-drive transportation across the board and V8 engines of any kind were regulated to the largest luxury sedans, police cruisers, trucks and large vans.

The Development Car


Gen III Challenger engine bay


The development vehicle for our Hooker BlackHeart line of Gen III Hemi swap products for the 1970-1974 Chrysler E-body is this 1971 Dodge Challenger R/T, finished off in FC7 Plum Crazy. Outside of the HK Wheels, at first glance the Challenger presents itself as a driver, the kind of car you'd take out and cruise around without worry. And it is, but there is no LA small block or big-block under that hood. Instead, a 2013 6.4L Hemi, backed to a NAG1 five-speed automatic transmission provides the motivation, the soundtrack, and the soul of this Dodge. Rated at 485 horsepower and 475 lb-ft of torque straight out of the car it was plucked from using the SAE method (instead of the gross horsepower numbers used in 1971), on paper the 392 is at least on-par, if not past the vaunted Gen II Hemi. The 392ci unit is controlled via a Terminator X Max ECU that supports drive-by-wire capability and is still connected to the NAG-1 five-speed automatic transmission, which means that this Challenger can drive at Interstate speeds no sweat, even with some stout gears in the rear axle. With the hood shut, nobody will be none the wiser as to the modern-day powerplant underneath unless they take a look inside, where they will notice a couple of hints that give away the secret.

For the most part, the interior of the Challenger is stock...black plastic and vinyl cover every surface, and as you sit low into the bucket seat and slide behind the steering wheel, most of this seems correct for 1971. Slide the Pentastar-headed key into the steering column, give it a twist and as the 6.4L awakes from it's slumber, loudly announcing it's anger to the world at being prodded into life, and you will notice the glow coming from the gauges. In this Challenger, the standard gauge cluster has been replaced with a Dakota Digital unit that does a far better job at keeping tabs on the new powerplant than the stock cluster would have. As you put your foot on the brake and reach over to where the original "Slap Stik" shifter was, you will find that it has been replaced with a B&M Magnum Grip Pro Stick console shifter, complete with the shift buttons that will allow you to utilize the NAG1's "Autostick" shifting function. Pull the shifter lever into Drive and tip into the throttle, and the Challenger will pick up pace easily and smoothly. Slow, sane driving can is just as easy in the '71 as it would be in a 2017 Challenger. If you're brave enough to test out the power of the Hemi under the hood, however, you had better be ready. If the number one complaint about the 2008-current Dodge Challenger is that it's overweight, just wait until you take the engine that makes the newer car a force to be reckoned with out and put it into a car that weighs in about a quarter-ton less. The new car's acceleration is plenty fun, but in the old-school car, it becomes an event. The 6.4 roars with all the subtlety of a heavy metal rock concert and the velocity is borderline alarming, no qualifying term needed. Just punch the throttle, do your best to keep the rear tires from going up in smoke, and prepare to be astonished. If you've never experienced an E-body with that much power and capability before...well, there's a pretty good reason why these cars are worth as much as they are today, and looks are only one part of that program. For the kind of money you will sink into a 426 Hemi or wicked 440 build, look again at a Gen III Hemi swap. You'll find no wanting for power, plenty of buildable engines available right now, and you'll gain a powertrain that is daily-driver friendly in the process!

1971 Dodge Challenger R/T Parts List

PartPart Number
B&M NAG1 Pro Stick Swap Shifter, NAG1, With Center Console81188
Hays Steel SFI Certified Flexplate - Mopar Gen III Hemi Car40-510
Holley EFI Terminator X Max, Gen III Hemi 2013-Current, with DBW Throttle Control550-1424
Gen III Hemi VVT/SRV Harness558-132
MSD Solid State Relay 35AX4, Black75643-HC
Hooker BlackHeart Engine Mount Brackets, Gen III Hemi Swap, 1970-74 Challenger/Barracuda (with V8 K-Member)BHS566
Hooker BlackHeart Transmission Crossmember, 1970-74 Challenger/BarracudaBHS567
Hooker BlackHeart NAG1 Transmission Adapter Plate, 1970-74 Challenger/BarracudaBHS569
Holley mid-sump oil pan (VVT)302-61
Hooker BlackHeart Gen III Hemi Swap Long-Tube Headers, 1966-74 Mopar B/E BodyBH2358
Frostbite Aluminum Radiator, 4-Row, 1968-1974 Mopar B- and E-Body Gen III Hemi SwapFB701
Frostbite High Performance Fan/Shroud Package (FB225 and FB227 Radiators)FB529H
Holley Power Steering Pump Kit - Late Car, Low Pressure97-382
Holley Sniper EFI Fuel Tank System, 1970-74 Challenger, 255 LPH19-137
Holley EFI Hi-Flow BilletFuel Rail Kit, Gen III Hemi534-284
Earl's UltraPro Transmission Cooler825ERL

Note: Earl's hose and fittings are used throughout the Challenger in various locations, as well.

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