Head Diameter: 1.575 in. - Stem Diameter: .3136 in. - O/A : 4.923 1984-pontiac-firebird-esi1382254 The dual rate springs offer

The dual rate springs offer plenty of support

offering a perfect balance of performance and street versatility

giving you a lightweight yet extremely strong performance upgrade

and V6 auto Camaros

degrees C neg 60

Head Diameter: 1.575 in. - Stem Diameter: .3136 in. - O/A : 4.923 1984-pontiac-firebird-esi1382254 The dual rate springs offerManley Severe Duty Valves deliver the ultimate in strength, reliability, and high performance durability. Engineered for extreme gasoline engine temperatures, these valves are crafted from exclusive materials (XH 428 for exhaust and NK 844 for intake), offering unmatched tensile strength compared to competitive alloys. In fatigue testing at 40,000 psi and 1400F, Manley exhaust valves endured 100 million cycles, while competitors failed after just