"This car is a natural for the Boss Hemi swap. There is plenty of room between the shock towers, enough room for headers [you can reach past them with your hand], and enough room between the accessory drives and the radiator. The hood needs no modification for the air filter. It's close, but the right filter assembly will fit. A stock rear sump Moroso pan fits over the steering and crossmember perfectly. The cooling system is completely stock. All we did was space the bottom of the core outward an inch or so, but the top of the radiator is in the stock location."
Kaase stripped it down and installed a mock-up engine, then sent it to fabricator pal Chuck Lawrence in Hiram, Georgia, for motor mounts and headers. Back at Jon's shop, they built and dyno tested the 589 and installed it with the clutch, transmission, and driveshaft. It went over to Lawrence's for the close-up work--hoses, wiring, gauges, and the rest of the finish work.
Kaase: "The front drive is from Billet Specialties. It comes with a billet front cover, which has extra bosses for attaching the accessories and brackets. It comes with the front cover, water pump, power steering pump, an alternator, A/C compressor, and all the pulleys and brackets. Nothing bolts to the heads. As complicated as it looks, it only took an hour to completely assemble it. Like any good racers, we threw the instructions out and just winged it. I was really impressed with the quality and fit of this assembly."
As the Boss 302 was created to champion small-block performance and to rub fenders with the Chevrolet Z28 in the Trans Am series, in the big-block world, the Boss 429 was really a homologation special required for legality in NASCAR. Production for '69 was 859 units (including two Boss 429 Cougars). In '70, the total was but 499. Automatic transmission and air conditioning were not offered, but at least it had an engine oil cooler and the battery was moved to the trunk, largely to free up space in the motor room. Well, they still don't race Mustangs in NASCAR, so how come it wound up in one instead of the obvious Torino? Sorry, we can only guess at the back story on this one, but Ford marketers figured heavily on boosting the Mustang's image, so that's the way it was.
Kaase's remarks about the efficacy of modern speed parts made us think. The Boss 429 had huge ports and a marginal camshaft that really didn't take effect until the engine was really winding up, so low-speed torque pretty much sucked. His Boss Nine heads (which will fit on any 429-460 block) have holes just as large, but the advance in camshaft phasing and ignition technology "adjust" for these ancient and potential shortcomings. The same goes for the completely stock suspension. When the weak stuff breaks, they will amend the woe with stronger stuff.
Since the Boss Nine was finished a couple of weeks before it debuted at the PRI show, it has some work-in-progress teething issues. "It doesn't want to run very well below 2,500 rpm," said Kaase. "It farts and bucks. It's like driving something between a Pro Stocker and a pulp truck. No matter how careful I am with the throttle, and I'm talking Third and Fourth gear now, it literally wants to rip the tires off (laughs). Now that I've felt this thing, realistically, a 466-inch Boss Hemi would be about right for this car, but, as they say, anything worth doing is worth doing in excess."
As a work in progress, the...
As a work in progress, the Mustang chassis/suspension is bone stock. The Boss Nine is equipped with latter-day 18-inch American Muscle Magnum 500 wheels and thick Pirelli PZero Rosso rubber, but the motor has enough moxie to break 'em in Fourth gear.
About as slick as a moleskin...
About as slick as a moleskin biscuit, the Boss Nine has every bit of its assembly line interior. Colorful it ain't; functional it is. Note the just-the-right-height Hurst gear changer.
D&D Performance supplied the...
D&D Performance supplied the blast-shield/bellhousing and the Viperized T56. Kaase made the crossmember. The McLeod clutch assembly is twin-disc on an 11-inch steel flywheel.
Original cars had a working...
Original cars had a working hood scoop. Kaase wanted to stay away from that, so he used a NASCAR-flavored BSR air cleaner and bottom plate that drops the whole assembly cleanly away from the underside of the hood. Big Boss is nearly 600 ci large. Kaase's pal Chuck Lawrence did all the wiring and considerable finessing needed to make it all work.