For 1970, the Boss 302 received new tape stripe treatment which began on the hood, came down the front fender and then across the sides of the rear of the car. The standard wheel size was still 15 x 7, but a trim ring/hubcap arrangement was standard, instead of the Magnum 500s. Chrome Magnum 500s were still an option, but only for the Boss 302, as was the shaker hood scoop.
New for the Boss 302 was a redesigned dual exhaust system, Competition suspension, and the standard Hurst shifter. Smaller intake valves could also be found, along with aluminum valve covers which replaced the chrome ones from the previous year.
A gloss black hood scoop outlined the ’70 Boss 429, along with chrome Magnum 500s using a Boss 302 center cap. Available colors were Grabber Blue, Grabber Orange, Grabber Green, Calypso Coral and Pastel Blue. Only black or white was available as the interior color. For 1970, 499 Boss 429s were produced, as the KK numbers ranged from KK2060 to KK2558.
The consecutive unit number on the Boss 302 could be found on the engine block, and the Boss 429s had additional VIN numbers on the transmission, engine block and inner fenders.
In 1970 the Boss 302 was a Camaro killer, it could go 0-60 mph in 6.0 seconds. I was still only available with the special 302ci 290 hp high output engine. It had a close ratio 4 speed transmission, a 3.50:1 rear axle, a staggered shock competition suspension and a 16 : 1 steering box. What it did not have was an automatic transmission or air conditioning. You could buy a Boss in any color w you wanted as long as it was Wimbledon white, Bright yellow, Acapulco blue or Calypso Coral. There were a total of 1,628 Boss 302 cars manufactured in 1969. Although the engine was smaller than the 429, it was much more maneuverable on twisting roads, either one was a blast to drive and both are sought after classics.
On the interior, the Boss could be equipped with any optional interior package. The only interior difference was a manual choke knob located below the dash to the right of the steering wheel.
On the exterior, it received a blacked out headlight bucket, front spoiler, reflective “C” stripes on the side of the body, low gloss paint on the hood, low gloss paint on the deck lid and rear panel, flared front fenders, 15 inch argent colored Magnum 500 wheels, chrome lug nuts, and the rear quarter panel side scoop was removed.
Functionally, there was a 6150 rpm rev limiter installed on the left hand engine compartment side wall. This protected the engine against accidental over-revving by randomly shorting out cylinders when the RPMs exceeded 6150. Most of these governors are still in excellent condition today since they were bypassed when they were new! The Boss was equipped with front power disc brakes, a 16:1 steering ratio, a heavy duty front stabilizer bar, staggered shocks, and a heavy duty suspension.
Boss 302 features:
Boss tape stripe kit resembled a backwards “C” starting behind the front wheel well and migrating back the fenders and across the side to the rear of the car.
Standard wheel size was 15 x 7 . Tires were F60x15’s.
Chrome Magnum 500 deep dish wheels with a longer center cap were standard on the Bosses.
Shaker hood scoop was a 302 option, it was not available on the 429.
The Boss 429 had a gloss black hood scoop.
8000 RPM Tachometer and interior decor group.
Front disc brakes
Traction lock rear axle
High-back bucket seats with deluxe seat belts
There were no rear air scoops as found on other 1969 SportsRoof models.
Interior colors were either “Black” or “White”.
Exterior colors were
Aluminum valve covers.
Optional Rear Spoiler
Optional Rear Window Slats.
Standard transmission was the close ratio 4 speed transmission.
Late in 1969, Ford replaced their ford shifter with a Hurst shifter.
Dual color coded racing mirrors
The Boss 429 is one of the most unique Mustangs made. Its uniqueness lies in its rarity, its engine and simply for the fact that so much effort went into modifying the basic Mustang to make the Boss 429 engine fit.
Visually, the Boss 429 sits lower than other 1969-70 SportsRoof Mustangs. And compared to the Mach 1 or Boss 302, it has an understated image. Save for the Boss 429 fender decals and large hood scoop, the Boss 429 doesn’t have any stripes, blacked-out trim, wheel or rocker panel moldings or even chrome dual exhaust tip outlets.
The Boss 429 Mustang was a limited production Mustang designed to homologate the Boss 429 engine for NASCAR racing. It would have been more logical to use the Torino, after all that was the body style used for NASCAR, but for image reasons, Ford decided on the Mustang instead.
All were built at the Kar Kraft facility in Brighton, Michigan. This was the same facility that Ford used to build the Le Mans Ford GTs. Partially completed SportsRoof Mustangs that were destined originally receive the 428SCJ engine, were modified at Kar Kraft to accept the large 429 engine. The main difficulty was getting the Boss 429 engine to fit the Mustang’s engine compartment. To do so, the shock towers were relocated outward (by hand) and while they were at it, the suspension was lowered and moved further outwards 1 inch, using spindles and control arms unique to the Boss 429. This made the Boss 429 handle much better than other big-block equipped Mustangs. Other features included Boss 429 fender decals, manually controlled hood scoop, a front spoiler that was shallower than the Boss 302 spoiler, color keyed dual racing mirrors, engine oil cooler, trunk mounted battery, close-ratio four speed manual transmission 3.91 rear axle with Traction-Lok, 3/4 inch rear sway bar (the first Mustang ever to have a rear bar), chrome 15×7 Magnum 500 wheels with F60x15 Goodyear RWL Polyglas GT tires. All Boss 429s came with the Deluxe Decor interior, 8000 rpm tachometer and AM radio.
The Boss 429 engine was based on a strengthened version of the production 429. These blocks have HP429 cast into the front of the block (driver’s side). It used four bolt mains, a forged steel crank and forged steel connecting rods. The big deal with this engine are its aluminum cylinder heads which featured a modified Hemi type combustion chamber which Ford called “crescent”. These heads used the “dry-deck” method, meaning no head gaskets were used. Each cylinder, oil passage and water passage had an individual “O” ring to seal it. The Boss 429 used a single Holley four-barrel carburetor rated at 735 CFM mounted on an aluminum intake manifold. 1969 versions used a hydraulic lifter camshaft; 1970 models got a mechanical lifter camshaft along with an improved dual exhaust system.
Each Boss 429 Mustang came with a KK sticker placed on the inside of the driver’s door above the Ford Warranty Plate which signified Kar Kraft’s production number. The first Boss 429 was numbered “KK NASCAR 1201” while the last 1969 is numbered 2059. Some Boss 429s may have this silver tape stripe missing; a small brass plate was substituted by Kar Kraft on a small number of cars.
Besides the Boss 302, the Boss 429 was the only other Mustang that had its Serial number stamped on the back side of the engine block assembly, on the inner front fender panels, on the transmission housing and on the chassis itself.
1969 Boss 429 Mustangs were available in five colors: Wimbledon White, Royal Maroon, Raven Black, Black Jade, and Candy Apple Red. 1970 versions were painted Grabber Blue, Grabber Green, Grabber Orange, Calypso Coral and Pastel Blue. All 1970 Boss 429s came with a gloss black painted hood scoop.
One would think that the Boss 429 would have been a street terror- given its impressive specifications. At best, in stock form, it equaled the 428CJs performance. The usual after market bolt-on modifications were extremely effective on waking the engine up. But as far as Ford was concerned, there was no reason to promote this Mustang- it’s only purpose for being was to get that monster engine homolugated.