This is from one of the original press releases from GM.
GM Performance Parts Launches ZZ430 Small Block
Las Vegas, NV, Nov. 3. - The new ZZ430 engine is the highest horsepower
small block crate engine GM Performance Parts has ever produced. And, with
GM Performance Parts planning to build only 430 of the engines, they will
probably be snapped up with the same kind of speed the engine delivers in a
street machine or a race car.
Limiting the production build to 430 units will create an added aura around
the engine, GM hopes. Each engine will be numbered, and will come with a
version of GM Performance Parts' 18-degree racing valve covers engraved with
the GM Performance Parts and ZZ430 logos. A jacket and cap, both with
matching serial numbers, also will come with the ZZ430 engine.
The ZZ430 is based on the small-block, 350-cubic-inch ZZ4, which delivers
355 horsepower and has earned a solid reputation for speed and durability.
True to its designation, the new ZZ430 produces 430 horsepower. This engine
is designed for use in 1973 and older street vehicles and any year off-road
The keys to upping the performance level, according to Michael Fellberg,
general product manager for GM Performance Parts at General Motors Service
Parts Operations (SPO), are a pair of new aluminum "Fast Burn" cylinder
The 23 degree Fast Burn heads are so named because of the head's ability to
quickly and completely burn the air/fuel mixture, creating higher cylinder
pressures that result in more torque and horsepower. The Fast Burn head uses
GM Performance Parts' cast-ported technology. Cast-ported means that as
incremental improvements in flow, combustion and cylinder fill were
identified during the development process, those improvements were
incorporated in the casting and machining tooling. As a result - unlike most
after-market performance heads - the Fast Burn head achieves maximum
performance "out of the box," with no additional porting needed to improve
The ZZ430 also gets a performance boost from a hotter camshaft, the "Hot"
cam originally used on the LT4 engine. The ZZ430 uses off-the-shelf
23-degree roller rocker arms and valve train components."