"I have always wanted a Boss 429 Mustang because I consider it to be Ford's masterpiece of engineering. The problem is, considering their present value [approximately $500K], I was as far away from being able to afford one in 1969 as I am today. If I could buy an original, it would be far too valuable to drive. With the release of our Boss Hemi engine parts, the next logical step was to build our own version, rationalizing that a complete running car would showcase the new parts and create a new market for our parts sales," said the gleeful Jon Kaase.
"Let's be honest here. I wanted this car! I want to drive it home and give my family and neighbors a ride. Most of them think I have a garage that does quick oil changes. They have no idea. I hadn't driven anything with over 360hp since 1974. With 800 ft-lbs of torque and 900 hp, this car is a real handful."
We were yakking with Jon at the recent PRI show about the black beast in his booth. Then the thread wound into a trip we'd made to his old shop a dozen years past. We had gone there to document the building of an 812-inch IHRA Pro Stock motor. Forgot what it made, something like 1,400 on the motor. Kaase said that times have changed, drastically, and that same configuration outfitted with the latest parts would put out at least 1,900. We'll come back to this in a minute.
Look at the Boss Nine Mustang. Kaase's vision was based on a stock-appearing car, one that you would buy from a dealer with the biggest motor available. It was rated at a paltry 375 hp. Kaase's version makes 900. In the day, the 1969-70 Boss 429 came with 7-inch Magnum 500 rims and F60 Goodyear Polyglas GT rubber, and perhaps the most arresting thing about it was the distinct lack of stripes, black-out trim, wheel or rocker panel moldings, or chrome exhaust tips. All it said was "Boss 429" on the fenders, and it carried a functional hood scoop that practically disappeared when the body wore dark livery. Kaase's Boss Nine fairly reeks that aura and looks for all the world like it just rolled off the Kar Kraft (Brighton, Michigan) "assembly" line, modern Magnum rims and all.
Part of that image comes from a new Mustang that Kaase bought from B.F. Evans Ford in Livermore, Kentucky. It had but 180 miles on the odometer, and only because Evans' guys drove it to Nashville, where Kaase's guys loaded it on a trailer for the final miles home. All the build tags and stickers are still in place, adding to the dj vu mystique. "It was worth it because it's new and it's a pleasure to work on, no dirt, oil, or road gunk," quipped the low-key Kaase.
The biggest obstacle for Kar Kraft was that skinny space between the shock towers, a place never meant for an engine with the girth of the Boss (see "Total Performance," p. 44). Their techs had to cut out, rebuild, and relocate the towers to make room for the big Blue Crescent (semi-hemispherical combustion chambers) cylinder heads, and with little space to spare even at that. Kar Kraft also lowered the suspension by about an inch, using control arms and spindles specific to the Boss 429. We asked Jon about how the Boss Nine fit in that modern engine compartment. He smiled, Cheshire cat-like. "You could say it just sort of fell in there. We didn't have to trim, cut, or rebuild anything for it to take the motor. We didn't even have to take the hood off."
Then: "I should have measured the stock engine crank centerline at the front, with respect to the sides. The tailshaft and rear crossmember measured to be in the centerline of the car, and the pinion is also centered between the wheels. The thing is, I remember the valve covers to be unequal distances from the shock towers, offset to the right. Is the engine in these [new] cars at an angle? With the Boss engine in place, the tailshaft is centered and the valve covers are closer to the right, just like stock.