Kaase Race Engines 429ci big-block Ford combo – Mill of the Month

Howard Astill has been tasked with fitting this monster 8.6-litre donk into a street-driven retrotech XC Falcon

Photographers: Will Horner

WHILE many know of the Chrysler Hemi’s ferocious reputation in American muscle car lore, Ford had its own ‘semi-hemi’ race-ready big-block. The Boss 429 was fitted to Ford’s angriest Mustang as a way of homologating the 7.0-litre brute for use in NASCAR, even though Ford campaigned the mid-sized Torino in that series.

First published in Street Machine’s 2020 Yearbook. Photos: Will Horner

The aero-slicked Boss 429 Torino Talladega won far more races and championships than Mopar’s more famous Charger Daytona and Plymouth Superbird ‘wing cars’ before they were all banned by ‘Big Bill’ France in the early 70s. Today you can still buy a Hemi-stomping big-block Boss Nine, but you’ll need to call up Kaase Race Engines, not Ford.

“I believe my customer actually bought this engine off the Kaase Engines stand at SEMA,” says Howard Astill, who has been tasked with fitting this monster donk by its owner, Peter. “It is one of Kaase’s Boss 429s, and Peter brought it to me with the car and the transmission.”

That car is a four-door XC Falcon dubbed BOSSXC, which will be packed with all the creature comforts and tech of a late-model Falcon, including a six-speed ‘box, cruise control, climate air con and more.

Packing 773hp at 6400rpm and a thumping 700lb-ft of torque at 5100rpm, this 7.0-litre fatty will be an epic street engine. Its 9.8:1 comp ratio will allow Peter to fill it with regular pump fuel, while the hydraulic-roller cam and Crane Z-bar lifters offer less intensive maintenance than a flat-tappet or solid-roller cam. The bottom end also features a Lunati crank and forged rods, while Trend 3/8-inch pushrods swing WW Engineering 1.75:1 shaft-mount rockers under the killer polished aluminium Boss Nine covers.

The heads are Kaase’s own take on Ford’s Boss 429 ‘Shotgun’ jobbies, made out of aluminium and modified to work with modern cam specs better suited to the 2.30-inch intake and 1.9-inch stainless valves, which operate beehive springs.

“I’m going to build the pipes for it here,” says Howard. “I’m looking at a four-into-one with a two-inch primary, and a system built out of SpinTech oval piping and mufflers.”

Up top is Kaase’s DCOE-style Boss Nine stack injection, which will release all the glorious dorts when the go-pedal is mashed. Interestingly, Kaase’s manifold features a plenum on the underside so it pulls vacuum from all eight cylinders, improving idle quality and part-throttle response.

The front of the big Boss wears a polished Billet Specialties serpentine belt kit, with BOSSXC running both power steering and air-conditioning, although the polished engine will have to cop some mods before it goes into the Falcon’s engine bay.

“The rear pick-up sump will have to be altered to suit the steering rack the XC runs,” explains Howard. “The car had been at another shop, and Peter supplied it to me with the front and rear ends in place, with the motor and the ’box on the side. It was originally set up for a Windsor, but the motor that was going into the XC went into another project of his.”

We’ll have a full workshop tour and a closer look at BOSSXC in the near future.


“We’ll be using the stock late-model Falcon ECU to run the Kaase,” Howard says. “The engine has an MSD Pro Billet distributor in it with a normal coil, so I’m not too sure whether we can use that with the Ford ECU at this stage.”

Astill Designs,
South Coast, NSW