It’s considered one of the rarest muscle cars out there, is certainly one of the more valuable ones, and has one of the more interesting creation stories. The Ford Mustang Boss 429 isn’t a drag package car, but instead a strange combination of Mustang, NASCAR, and a poker face that had to be seen to be believed. The Mustang part is there…Ford’s pony car was still rolling on it’s tsunami of success, and while the 1969 version had gotten bigger, it was still selling quite well. The NASCAR part is the engine, a punched-up Ford 385 block with semi-hemispherical heads that was no truck motor…it was Ford’s ballistic missile, the one aimed squarely at the Mopar camp and the 426 Hemi. For homologation purposes, Ford had to sell 500 engines in production cars to the public to qualify. How the massive mill ended up getting jammed into the Mustang’s engine bay is a call steeped in lore, but Kar Kraft, who was contracted by Ford to build the Boss Nines, hacked and cut and worked the front end to fit the big mill. Now, about the poker face quip: You know the numbers of the Boss 429’s competition: the 426 Hemi in the Barracuda and Challenger, rated at 425 horsepower. The COPO ZL-1 Camaro, with it’s 427ci Rat under the hood, at a very conservative 430 horsepower. Yet Ford’s take on where the Boss Nine sat was rather understated: 375 horsepower, and 450 ft/lbs of torque. If you believed that, you were a special kind of sucker. Even before the small carburetor, headers and other tweaks were performed, the 429 was pushing well past that figure, somewhere closer to 500 horsepower for base-level measurements. Fresh from a full restoration, this Mustang is as close to factory as they get, and Jay Leno gets to tool around in it…his first drive in a Boss 429 Mustang. Yeah, we’re a bit jealous.
There is a white ’69 locally. I have seen at several car shows. The let down is how sedate it sounds. The cam in it barely lopes at all. If it didn’t have the Boss 429 on the fenders, hearing it would have me thinking it was just a lowly Windsor powered.
Cool car at least it gets driven . Nutso about those carbs my car had a boss 302 carb on it when I found it and I seem to remember it being a 780 bigger than even the big block shelby cars .
Both the Boss 429 and 428 Cobra Jet use 735 CFM 4 BBL carbs. The Boss 302 uses a 780 CFM carb.
To make a Boss 429 run you have to replace the carb, the cam and the exhaust headers. Not like the Chevy L88/ZL1 where all you have to do is replace the cast iron exhaust headers.
The Boss 429 is a heavy engine: 680 lbs. An L72 427/425 HP weighs 645. The Chrysler 426 Street Hemi weighs 765.
Most of these things had glass packs or header mufflers on them back in “day 2”. It was only recently that I became aware of how lame Ford’s stock exhaust systems sounded up against a stock Mopar and some of the GM contingent. That Boss 429 has less of an exhaust tone than a 383 Sport Fury or even a 396 Impala.