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

Lubrizol Additive Solutions for GF-7

Lubrizol’s additive solution to meet new performance requirements will enable oil marketers to upgrade to ILSAC GF-7 with ease.

Lubrizol has announced the launch of its new passenger car engine oil additive technology Lubrizol PV1710 that will enable oil marketers to meet the performance requirements of ILSAC GF-7, the new passenger car engine oil specification that will go into effect on March 31, 2025.

Lubrizol PV1710 offers customers a simple, purpose-built solution formulated to meet ILSAC GF-7 credentials and with a capability to reach dexos 1 specification. Core technology testing is complete and additional testing is underway to cover extensive industry requirements to provide maximum flexibility to customers. Lubrizol PV1710 will be available well in advance of the first-license timeline, enabling oil marketers to fully prepare to go to market.

Cosworth Returns to Goodwood Festival of Speed

At this year’s Goodwood Festival of Speed, Cosworth will feature an array of machines with its innovative engineering at their heart.

Engine Ice Launches Refreshed Website

Related Articles – Choate Engineering Performance to Lead Webinar on the Cummins Engine – Niterra Announces Todd Cullums as VP of Manufacturing Operations – Supreme Court Decision Helps Auto Aftermarket Against Federal Overeach

Choate Engineering Performance to Lead Webinar on the Cummins Engine

Cass Choate of Choate Engineering Performance is returning to PERA to talk about the Cummins diesel engine. He will take advantage of his vast experience to delve into its problems and what his shop has learned about fixing them. Related Articles – LSI Chemical Adds New Business Development Manager – Starrett Introduces Touchscreen Wireless Digital

Niterra Announces Todd Cullums as VP of Manufacturing Operations

Todd Cullums has been appointed vice president of manufacturing operations for Niterra North America, Inc. Cullums has been a Niterra associate for over 20 years and held the previous position of director of manufacturing, overseeing operations at its Sissonville, WV facility.  Related Articles – Radford Racing School to be Final Stop on Hot Rod Power Tour

Other Posts
Alex Null’s 6.4L Ford Powerstroke Engine

During our trip to Dallas this year, we spent a day in Weatherford and visited Alex Null and Summit Diesel. We were treated to the details of Alex’s own 6.4L Ford Powerstroke engine build he is finishing up for a race application. It’s our Diesel of the Week brought to you by AMSOIL INC. Related

6.4L Ford Powerstroke
COMP Cams Thumpr and Mutha’ Thumpr NSR Camshafts

The Thumpr NSR camshafts are a perfect choice for near stock to mildly modified engines. The Mutha’ Thumprs work best in modified naturally aspirated and supercharged engines.

COMP Thumpr camshafts
Single-Turbo 6.4L Powerstroke Engine

After a few different things fell into place with trucks and other 6.4L Powerstroke engines, Alex Null, owner of Summit Diesel, was able to build this particular 6.4L Powerstroke into a race engine for his Ford F250 and the 7.70 index class. Check it out!

6.4L Powerstroke engine
Twin-Turbo Gen II Coyote Engine

We’ve been more apt to check out Mustangs recently thanks to the high-performance potential of the Coyote engine, and Kolby Bouck’s 2017 Mustang with a Gen II Coyote engine is definitely no exception. Check out the details of this twin-turbo Gen II Coyote engine build!

Gen II Coyote engine