New, powerful Kaase Boss Nine Hemi kit to suit 429-460 big-block Fords:

Written by Moore Good Ink  

Winder, GA, January 2009:  Though this new Boss Nine retrofit Hemi kit produces 100 horsepower more than its counterpart, the P51 Wedge—Kaase’s competent replacement for the Cobra Jet, it is not the power advantage that attracts the punters, but instead it is the look. Still the spectacle of a ‘69 Boss Mustang power plant maintains an indestructible image for many. 


Kaase has a genius for these things: he contrived to set his sophisticated Boss Nine cylinder heads and intake on a stock 429-460 big-block Ford, added an upgraded oil pump and dressed the package with evocative Boss 429-style valve covers.  This new system makes more power, makes it reliably, and looks terrific.
In his quest for power increases, he revised the shapes of the combustion chambers, the intake and exhaust ports, and changed the spark plug locations.  For reliability, a new rocker system was devised in conjunction with W.W. Engineering to eliminate the adverse offsets of the stock Boss parts. And for availability and economy, Manley big-block Chevrolet valves with 11/32-inch stems were selected.  This Boss Nine kit adopts stock 460 head gaskets (Fel-Pro 1018), intake gaskets, and exhaust gaskets and uses 429-460 stock internal oil drain-back holes.  


Intake Manifold: When tested on a 466 CID engine, the new intake manifold proved 50 horsepower better than the best NASCAR single-plane counterpart and 100 horsepower better than the factory dual-plane manifolds supplied with 1969-1970 production cars. Un-ported, this Kaase intake has sustained over 1000 horsepower on a well-built 600 CID engine. Moreover, on an engine as small as 429 CID, it has supported full engine loads at 2300 rpm. The intake, which also fits any of the OEM Boss heads, is available for either the 4150-style (750-850 cfm) carburetors or 4500-style (Dominator) carburetors.  


Oil pump:The mounting foot of the OEM oil pump of a 385-series big-block Ford is prone to fracture.  Kaase’s new pump has sturdy mountings to eradicate pump breakages and is equipped with dual oil feeds to improve idle and high-rpm oil pressure.  It was developed to operate with front or rear sumps and is provided with superior ARP mounting studs and 12-point nuts.


For further information contact:
Jon Kaase Racing Engines, Inc.
735 West Winder Ind. Parkway,
Winder, GA  30680,
Telephone (770) 307-0241 or email:
For latest offerings, visit the Kaase website at:


  1. How much for complete boss heads – pushrods, rockers, exhaust flanges, and intake for 600in motor?

    • Gary,

      The Boss Nine heads set up for a Hydraulic roller camshaft are $4350 per pair, the shaft rocker system is $1575, pushrods would be $160 for a set, and mild steel header flanges are $110 per pair. If you go to our website we show all of the different offerings on Boss engine components or you can call us at (770) 307-0241

    • I own a 1978 Bronco with a 351 and considering a 460. A 460 with Boss 429 heads would be amazing. I’m saving up! 😎

  2. What are the parts and costs involved in fitting your B9 heads to a 429/460 block with flat-top pistons. This is for a street car and not for racing.

    • Merv,

      Could you email our team directly at We’d be happy to review your concept and discuss the parts required. Due to the particular valve locations of the Kaase Boss Nine, you will obviously need to change the pistons. From there we can supply you with as much or as little as you desire regarding performance, sound, and appearance.


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