Welcome, once again to Clash of the Classics. This month we’ll head back to 1970 to revisit two of the coolest cars ever produced, the 1970 Ford Mustang Boss 429 and the 1970 Dodge Hemi Challenger. 1970 was an interesting time here in our nation, the Kent State shooting incident was headlining newspapers across the country, music fans were mourning the Beatles’ breakup and on Jan 11th the Kansas City Chiefs upset my beloved Minnesota Vikings 23-7 in Super Bowl IV.
In the automotive world, things were much brighter, the 1970 pony-car market was at its peak and both Ford and Dodge were determined to mine as much profit as possible from their division models. The Blue Oval group invented the market with the Mustang. Throughout the mid to late 60’s, Ford dominated the segment like no other manufacturer, and the folks at Dodge wanted a seat at the table.
Dodge’s response to the Ford Mustang was appropriately named “Challenger” and while it could be argued they were a bit late to the party, one thing is certain, it was… “Late but worth the wait”.
Let’s begin with a look at the ‘70 Mustang Boss 429.
Affectionately known as the Boss 9, the original series Boss 429s are amongst the most sought-after vehicles in the classic car world. With a limited run of only two years, it’s estimated a total of 1359 original Boss 429s were ever produced.
The car’s development was fueled by one idea; to challenge the mighty Chrysler 426 Hemi in NASCAR’s Grand National Division. Ford decided to use the Mustang platform with a new engine design. The 427 and 428 series engines were successful but somewhat aging. The new 429 was fresh and considered to be the answer to Chryslers’ dominant 426 Hemi. However to use the engine on the NASCAR track, Ford had to first homologate a minimum number of engines into regular production cars, hence the street versions of the Boss 429 Mustangs were born.
Because Ford’s powertrain division was already committed to other projects at the time, the development of the Boss 429 Mustang was farmed out to a company called Kar Kraft. To say there were serious obstacles to overcome would be an understatement. To begin with, the 429 simply did not fit in the engine bay as it was over 2 inches too wide.
Kar Kraft engineers had to push the suspension outward by roughly an inch on each side which required a complete redesign of the shock towers. The upper and lower suspension arms had to be redesigned with new heavy-duty front springs. Even the brake booster had to be redesigned to clear the huge valve covers.
The rear suspension was redesigned with a massive rear stabilizer bar, heavy-duty springs, and staggered shocks. Because of the extensive redesign, the overall profile was considerably lower and because of that, a new design front spoiler was used to preserve ground clearance.
The new engine included large alloy hemi-style cylinder heads with 2.3-inch intake valves, four-bolt main caps, and a forged steel crank. It used a hemispherical “crescent” type combustion chamber that’s more akin to the traditional Hemi engine used by the rival Dodge.
The Boss 429’s official horsepower was listed as 375, and the torque as 450 lb-ft. The actual horsepower numbers were likely higher as it was common practice back then to minimize horsepower ratings for insurance purposes. A more realistic rating was probably near 475 hp. The transmission was a 4-speed top-loader combined with a 3:91 posi rear differential.
The original prototypes went through extensive testing and no details were overlooked. Not only were there emissions tests that had to be passed but there was also a battery of environmental tests conducted to determine the integrity of the powertrain in all driving conditions.
The entire development process yielded one of the most refined vehicles of the time, some might even argue the car was over-refined. Ford management approved every design change and sent the car to production. Unfortunately, it was a short run, and by 1971, both the Boss 429 and the Boss 302 were replaced by the Boss 351.
Up until a few years ago, I hadn’t had an opportunity to experience a true original Mustang Boss 429. That all changed when our team at “Horsepower for an Hour” was hosting the Fabulous Fords Forever event in Southern California.
John Force was our celebrity guest at the event and after we finished interviewing him and his team, we set out to find a true Boss 429. Of the roughly 480 Mustangs in attendance that year, only one true factory Boss 429 Mustang made it to the show. After a quick discussion with the car’s owner, we were invited to drive it.
Nothing can truly prepare you for the experience, it is almost surreal. The car was pristinely preserved and handled extremely well. We found ourselves out on Beach Blvd in Buena Park California feeling invigorated and transported back in time. The acceleration was impressive as was the entire overall feel. It was a highlight reel moment for me, one that I’ll be eternally grateful for.
Let’s look briefly now at the ‘70 Challenger Hemi R/T.
The 1970 R/T Hemi Challenger is arguably one of the most iconic and valuable classic cars we’ve ever showcased here at Clash of the Classics.
As we discussed earlier, Dodge was considerably late to the pony-car market, but with the introduction of the R/T Challenger with the 426 Hemi, they certainly made it worth the wait.
First appearing in the Fall of 1969, the all-new Challenger made its debut alongside a newly redesigned Plymouth ‘Cuda. The two cars made it clear Mopar was a serious contender in the pony-car market. Prior to the release of these models, Dodge had made an impact in the muscle car market with the iconic ‘Charger, Super Bee, and Coronet R/T designs, now they were poised to make a run at the Mustang and Camaro.
One clear advantage Dodge had was a monster powerplant under the hood. The 426 Hemi has a long history all the way back to 1951, but the engine most of us think of was redesigned in the early 1960s and released in 1964.
It is possibly the most iconic and legendary engine ever produced in the muscle car era. Earning the respect of both Ford and Chevy loyalists, this engine set what would become the standard by which all other big blocks would be measured for years to come. Whether on the street or the track, the 426 dominated throughout the 1960s and 1970s.
The engine that was found in showroom models was rated at 425 hp with just under 500 lb-ft of torque. Some independent tests performed at the time put the horsepower closer to 435 with a torque rating of 515 lbft. Either way, the engine was an engineering marvel.
Nicknamed the “Elephant Engine” due to its enormity, it filled the engine bay of the new Challenger. Adding to its already impressive look were a pair of four-barrel Carter AFB carburetors that served to feed copious amounts of fuel to the beast.
Transmission options were either the 4-speed manual A833, or the Torqueflite 727 automatic. Handling all that power at the rear of the car, typically was an Auburn 9.75-inch limited slip differential with 3.55 gears. Dodge also offered a 3.90 gearset but was seldom ordered. One of my favorite design features of the car is the shaker-hood. I’ve always favored that style and look on a street performance car but for some reason, Dodge discontinued it after the 1970 model year. Presumably, the reasons had to do with cost and problems associated with owners in colder and wetter climates.
Under the car, the suspension was adequate but like most cars of the ‘60s and ‘70s, it had issues at higher speeds due to design limitations of the time. The R/T models had the advantage of a heavy-duty stabilizer bar and heavy-duty shocks up front, and the increased spring rate at the rear suspension helped stabilize the car further. Still, overall, the suspension was the area of the car that was in the most need of attention.
Inside, the car was well-designed and developed. The Rallye instrument cluster was track-influenced with a 150 mph speedometer, individual analog gauges, and an 8,000 rpm tachometer. The steering column was also interesting, as a unique cover was added to it that gave it a fighter jet feel.
It is estimated that Dodge produced 18,500 Challenger R/T’s in 1970. Of those produced, only an estimated 356 were equipped with the 426 Hemi engine. 287 of them were hardtops, and 69 of them were convertibles. It is currently unknown how many of those cars remain today, a Hemi equipped concours level convertible would be inestimable.
The Challenger R/T ultimately received its moment of stardom when Hollywood cast the car in the all-time hit classic movie “Vanishing Point”. In the film, Kowalski’s mission is to get a 1970 Challenger from Denver to San Francisco in 15 hours.
Along the way, he finds himself meeting all sorts of helpful strangers and gets involved in some pretty memorable car chases. He takes on a larger-than-life persona when a random radio station begins covering his journey.
If you haven’t seen the movie, or if you’ve forgotten most of it, I recommend you spend an afternoon becoming reacquainted, it is truly a classic.
The battle between the ‘70 Boss 429 Mustang and the ‘70 Challenger R/T Hemi has been hard fought and it’s difficult to choose a winner. Both cars are unique and true icons, however, there can be only one winner and the nod this month goes to the Dodge Challenger.
The deciding factor is the 426 Hemi engine. Few would argue its dominance in the automotive industry, it is legendary in the most rugged sense and seemingly will never be duplicated.
As always, we’d love to hear from you, let us know which car you prefer and why. Until next time when we take a ride on a classic highway, stay safe… stay timeless… stay classic!
About the Author
Donny Caccamise is an Automotive Technology Graduate and a Certified Master Technician with more than 40 years of automotive industry experience. Before retiring, he hosted the Nationally Syndicated Automotive Talk Radio Show “Horsepower for an Hour” airing on 161 AM and FM radio stations across the nation. He is a retired member of the ATRA Board of Directors, and retired transmission shop owner. Vintage and classic cars are his specialty. Contact Donny at donnycaccamise@gmail.com
The street Hemi’s horse power was and has actually been tested at 470 horse power not 435. In all my 70 years I’ve never heard anyone mention nor write 435 horse power for a street Hemi. It is significant imo that todays Top Fuel dragsters still
use Chryslers hemi design exclusively and not Ford’s.