PAC-1529 Valve Springs – 1500 Series Dual Spring for GM LS & Endurance Circle Track Solid Roller applications.

The PAC-1529 is PAC Racing's top-tier 1500 Series dual valve spring, as used in Cup Cars and endurance track racing.Built for high-RPM endurance, solid roller cams, and GM LS Gen III/IV race builds. Nitrided PACaloy wire, Nano-Peen™ surface treatment, and ID/OD chamfered for maximum fatigue life. 

If your engine sees sustained high RPM, big lift, and long race seasons, the 1500 Series is engineered to outlast standard performance springs

1500 Series Key Features

• Full nitriding – durable surface, better compressive stress
• Nano-Peen™ surface treatment – extended fatigue life
• ID/OD chamfering – clean retainer fit, reduced stress risers
• PACaloy super clean wire – proven race-grade material
• Designed for circle track, endurance, and high-cycle race engines

PAC-1529 Specifications

• Type: Dual valve spring (no damper)
• Outer Diameter: 1.284 in
• Outer Spring ID: 0.900 in
• Inner Spring ID: 0.630 in
• Installed Height: 1.900 in
• Seat Load @ 1.900": 180 lbs
• Seat Load @ 1.800": 236 lbs
• Open Load @ 1.150": 600 lbs
• Spring Rate: 560 lb/in
• Max Valve Lift: 0.750 in
• Coil Bind: 1.085 in
• Mass: 99 g
• Sold as a set of 16

PAC-1529 Load Chart – Height vs Pressure

What is the PAC-1529 used for?

The PAC-1529 suits GM LS Gen III/IV solid roller applications, circle track endurance racing, and high-cycle race engines running up to 0.750" valve lift. Common fitments include LS1, LS2, LS3, LS7, LSX, and Chev SBC / BBC race builds with compatible retainers and locks.

Why choose PAC-1529 over standard dual springs?

• Full nitriding for fatigue resistance under sustained high RPM
• Nano-Peen™ surface treatment – longer service life
• PACaloy super clean wire
• ID/OD chamfered and polished – reduces stress risers
• Proven in NASCAR and 24hr endurance applications