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834hp 429 Boss Ford Engine Build - 834HP Kaase Bos

Jon Kaase Has Cast A New Boss 429 Hemi Head With Wind Tunnel Airflow That Begged Us To Build An Equally Angry 460 Ford. That Became Our . . .

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Comp mechanical roller Cam


DURATION AT 0.050 (GROSS*) VALVE LIFT LSA
Intake, TK-series lobe 273 0.790 109
Exhaust, HXL-series lobe 280 0.787

Lash is 0.024/0.026-inch intake and exhaust. *Note: Gross lift is before lash. To obtain net lift, subtract lash plus any measured valvetrain deflection. It is not unusual to experience perhaps 0.020 inch of deflection, especially with these long pushrods and rocker arms.

1. Kaase also spec'd the Comp solid roller camshaft, but you'll only find it in the Comp Cams specialty lobe catalog. Kaase chose the TK- and HXL-series intake and exhaust lobes. Comp's description lists the TK series as "intense." These are lobes designed for drag racing, but Kaase thinks they would survive on the street and not be too abusive to the valvesprings.

Boss Nine Heads
This is where it gets fun. Back in 1969, Ford was all about stuffing giant ports into many of its engines. Airflow was king, and engines like the Boss 302, 351 Cleveland 4V, Boss 429, and the Tunnel Port 427 were headliners. While automotive performance history may have shunned those efforts, we think the ports weren't necessarily too big; the engines weren't nearly big enough. With new Boss Nine Kaase heads blessed with tons of airflow, it became a moral imperative to punch up the displacement to 21st century dimensions.

Kaase focused on eliminating all the factory quirks that have always stood in the way of building a reasonable Boss motor. Those factory O-rings had to go, as did the oddball separate oiling passages through the head as opposed to lubing through the pushrods. He also managed to ensure his heads could return most of the oil back to the engine through production channels. Other limitations Kaase faced included maintaining all the factory intake and exhaust port positions along with valve angles and all the classic external visual cues such as the undulating valve covers. Even the combustion chambers are similar to the original semihemispherical shape. That description comes from the twin flats or quench areas found on opposite sides of the chamber that help create turbulence in the chamber, which is something a true Hemi has trouble creating. A better description of the chamber might be more like a wedge with opposing angle valves. Kaase then tweaks the chambers with full CNC machining. The castings also incorporate pedestals for those Mississippi-bridge-like exhaust and intake rocker arms, which defrays some of the cost of the W. W. Engineering 1.75:1 rocker system. If you happen to own a set of original Boss 429 valve covers or intake/exhaust manifolds, those parts will also bolt right up to the new Boss Nines.

Flow Chart

VALVE LIFT BOSS INTAKE BOSS EXHAUST E/I PERCENT
0.100 79 65 82
0.200 161 128 79
0.300 244 186 76
0.400 308 244 79
0.500 366 272 74
0.600 409 287 70
0.700 406 299 74
0.800 396 306 77

Here's where massive area delivers huge flow numbers. Partly due to the 2.300- inch intake valve, the intake ports flow some very serious numbers. Yes, the 409 cfm at 0.600-inch lift is impressive, but do not overlook the equally impressive 308 cfm at 0.400-inch lift. Remember, the intake valve resides at max lift only once but achieves midlift numbers twice. Intake port velocity will suffer with a cross-sectional area that is closer to a Pro Mod drag race engine than for a streeter, but there's no denying the huge flow numbers. The exhaust ports do equally well to deliver a decent exhaust-to-intake (E/I) percentage of 70 percent.

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