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GM Atlas Engine Family
Crown Atlas Valve Spring Kit
$249.99
A planned matched kit of performance valve springs, retainers, and valve keepers for the GM Atlas engine family. Kits are being set up by engine-specific valve count, with the 4200 inline-six as the initial development application.
VALVE CONTROL FOR YOUR ATLAS BUILD
A performance camshaft changes what your valvetrain needs to control. Crown’s Atlas beehive spring package is being developed around defined seat and open pressures, paired with matching retainers and keepers.
DEVELOPED WITH THE 66H GRIND IN MIND
Crown selected the 90 lb seat and 210 lb open spring-pressure targets with the intended 66H camshaft combination in mind. Matching springs, retainers, and keepers brings the supporting valvetrain components together in one package. Final compatibility depends on the actual cam card, installed height, clearances, and completed testing.
ENGINE APPLICATIONS
- 4200 Inline-Six
- 24 valves
- Initial development application
SPRING SPECIFICATIONS
Design targets pending production testing. Open pressure is measured at a specified spring height, not at a lift value; the .449″ travel between measurement points is not a maximum lift rating.
- Engine Fitment
- GM Atlas engine family
- Spring Design
- Beehive
- Retainer Material
- Chromoly
- Installed Height
- 1.500″
- Seat Pressure
- 90 ±3 lb at 1.500″ installed height
- Open Pressure
- 210 ±5 lb at 1.051″ spring height
- Travel Between Measurement Points
- .449″
- Lift Note
- Maximum supported valve lift will be published after coil-bind clearance and assembled retainer-to-seal clearance are verified.
- Included Parts
- Performance valve springs, retainers, valve keepers
STOCK VS. CROWN VALVE SPRING COMPARISON
| SPECIFICATION | STOCK 2002–2005 | STOCK 2006+ | CROWN |
|---|---|---|---|
| Seat pressure | STOCK 2002–200550 lb — valve fully closed at 1.385″ installed height | STOCK 2006+65 lb — valve fully closed at 1.380″ installed height | CROWN90 ±3 lb — valve fully closed at 1.500″ installed height |
| Open pressure | STOCK 2002–2005136 lb at .400″ valve lift | STOCK 2006+137 lb at .400″ valve lift | CROWN210 ±5 lb at 1.051″ spring height |
| Installed height for listed seat pressure | STOCK 2002–20051.385″ | STOCK 2006+1.380″ | CROWN1.500″ |
The Crown valve spring and retainer combo works with both 2002–2005 and 2006+ Atlas 4200 cylinder heads.