Kaase Introduces Boss Nine Engine Kits for Common Ford 429-460 Big Blocks - Engine Builder Magazine

Kaase Introduces Boss Nine Engine Kits for Common Ford 429-460 Big Blocks

For engine builders, and enthusiasts with ambitions in hot rod engine assembly, Jon Kaase has introduced the Boss Nine in a new kit form.

KaaseBossKitRedValveCovWEb

Among the kit’s more prominent components, Kaase includes his noted semi-hemi cylinder heads with accompanying pistons, pins and rings as well as pushrods, shaft-mounted rockers and induction system. Everything to complete the full assembly is supplied.

Though power production may vary from 500 to 1,000hp in naturally aspirated form and up to 1,500hp under forced induction, it is the engine’s evocative appearance and heritage that heightens its universal appeal. Predictably, options abound and powder-coated cast valve covers are available in silver, red and black. Indeed, in any color that can be indentified by a paint code. In addition fabricated sheet metal covers are offered in natural aluminum finish.

In performance the Boss Nine’s magic is ignited by increasing its stroke length from the original late-nineteen-sixties specification of 3.590in. “Those big-port heads,” contends Kaase, “don’t like stroke lengths shorter than 4in., and respond enthusiastically to 4.150in, 4.300in or 4.500in, all of which we use.”

Because the longer 4.500in stroke causes the piston to protrude from the cylinder at bottom dead center, Kaase recommends a Race block or a “79” block, which has a 0.250in longer cylinder wall. Produced from 1979 to the mid-‘90s these can be identified by the nomenclature D9 on the block’s external surface. “They’re robust,” declares Kaase, “and we have one at the shop. It is 0.030in over-bored with 2-bolt main bearing caps and has taken the abuses of fourteen years of dyno testing. It usually generates between 900 to 1,000hp and we’ve used it on all Boss Nine and P-51 tests—it’s still going strong.”

kaasbossphoto2web

First flush of life in 2008, forty years after the original Boss 429 Mustang
To appreciate the full measure of the Boss Nine it is helpful to return to its origins. I never planned on building a Boss 429 head,” says Kaase, “until driving back from the Engine Masters Challenge in 2007. Though virtually everything we’d built at my shop had been a derivative of that engine, I knew if we used stock parts in an EMC contender it would fall apart. So we decided to build it with new, revised components. This approach allows anyone to build the engine using the popular passenger car 385-series block. It seemed a commonsense approach, but we wouldn’t have started the venture if not for the EMC. And six months later we would have dismissed the entire project because the banks were failing and everyone worried if they’d still have a job!”

Despite the racing successes of the original Boss 429 Mustang the semi-hemi cylinder heads were weak. The combustion chambers cracked and their thin decks leaked around the O-ring head gaskets. Also the original intake valves suffered premature wear as the unusually short rockers with poor operating geometry caused them to hammer the seats.

“Most of the revisions applied to the Boss Nine,” explains Kaase, “were incorporated to make it stronger and easier to work on.” The deck thickness of the cylinder heads (about 0.625in) is greater than the original and though the valves reside in the same place, the rocker arms attach to the head in a more simplified manner, making the assemblies less expensive.

Also, the exhaust rockers are a little longer, which moves the pushrod away from the deck. This revision improves pushrod clearance and eliminates grinding the block close to the water ports. Moreover, the Boss Nine combustion chambers are a little more efficient.

For enthusiasts looking forward to a romp through the springtime landscape, 429/460 BBF engines are readily available and inexpensive ($100) and the Boss Nine now flourishes in kit form.

For more information, visit: JonKaaseracingengines.com

You May Also Like

Proform Big Block HEI Distributors

Proform has added two big block Chrysler/Dodge/Plymouth HEI distributors to its product lineup. They now offer HEI distributors ranging from the small 273, all the way up to 440. These HEI’s are much larger than any other HEI previously developed, and Proform made sure to taper the shaft and remove the vacuum advance to reduce interference

Proform has added two big block Chrysler/Dodge/Plymouth HEI distributors to its product lineup. They now offer HEI distributors ranging from the small 273, all the way up to 440. These HEI's are much larger than any other HEI previously developed, and Proform made sure to taper the shaft and remove the vacuum advance to reduce interference with the valve covers.

Toyota, TRD Launch GR Supra Jr. Roadster for NHRA Racing

Toyota and Toyota Racing Development (TRD, U.S.A.) have unveiled the first-of-its-kind GR Supra Jr. Roadster set for National Hot Rod Association (NHRA) competition. NHRA will establish a new Jr. Roadster class for the NHRA Summit Racing Jr. Drag Racing League, although a launch date has yet to be set.  Related Articles – IMS Hall of

IMS Hall of Fame to Induct Tim Cindric, Tony George

The Indianapolis Motor Speedway (IMS) Museum has announced the IMS Hall of Fame Class of 2023 Inductees Tim Cindric and Tony George. The inductees will be formally celebrated at a ceremony and dinner on Friday, May 26, at the Indiana Roof Ballroom. Related Articles – More Details Revealed for the Future of Auto Club Speedway

Legends Nitro Funny Cars Series Announces Nine Races for 2023

Officials with the Legends Nitro Funny Cars series have announced its schedule will feature nine events in 2023. Teams campaign Funny Cars fueled by Nitromethane with body styles from the 1960s and 1970s, ranging up to 1982 and older.  Related Articles – Lubrication Specialities Adds to its Marketing Team – West Coast Stock Car/Motorsports HoF Names Five

Bill Introduced in U.S. House of Reps. to Prevent ICE Bans

U.S. Representative John Joyce (R-PA) has introduced H.R. 1435, the “Preserving Choice in Vehicle Purchases Act,” a bill designed to protect Americans’ right to choose the technology that powers their motor vehicles. The bill was introduced in response to the California Air Resources Board’s plans to ban the sale of new internal combustion engine (ICE) vehicles

Other Posts

Accessory Stud Kits From ARP

All ARP fasteners are manufactured in-house at California facilities to the industry’s highest standards.

BoostLine Connecting Rods for Nissan VQ37

The patented 3-pocket design was specifically engineered for demanding turbocharged, supercharged and nitrous applications.

Diamond Pistons’ Toyota 3UR-FE Piston Kits

Toyota’s 3UR-FE engine came to the market in 2007, and has since been a workhorse. As such, Diamond Pistons has announced a 3UR-FE piston kit.

Howell EFI Wiring Harnesses

Reprogramming of the existing ECM or ECM module supplied by Howell is required. ECM’s are reprogrammed to the vehicle’s engine and transmission specifications; i.e. gear ratios, tire size, cam changes, vehicle anti-theft (VAT’s) removal, etc.