Out of stock
SKU: PACPAC-1212X-16
MPN: PAC-1212X-16
PAC Racing Springs 1.355 Single Valve Springs RPM Series delivers precision valve control for small block Chevy engines demanding competition-grade performance. Engineered with a 380 lb/in spring rate and 1.180 inch coil bind specification, this set of 16 springs combines tight tolerance manufacturing with proven reliability in high-rpm applications where valve float and lift consistency directly impact horsepower delivery and engine durability.
The 1.355 inch outer diameter specification positions these springs within the standard bore range for small block Chevy cylinder heads, enabling straightforward installation without head modifications. The 380 lb/in spring rate provides adequate closing force to maintain valve seating across the rpm band while keeping pressure within the design envelope of stock or mildly modified rocker geometry. The 1.180 inch coil bind clearance allows proper valve lift without bind interference—critical for engines running aggressive camshaft profiles where deep valve lift is essential for cylinder filling and scavenging efficiency.
PAC Racing Springs valvetrain components are specified by engine builders targeting naturally aspirated small block competition, street/strip performance builds, and rebuilt stock engines requiring factory-correct spring replacement. A complete set of 16 springs covers both intake and exhaust positions on a standard eight-cylinder small block Chevy platform, simplifying parts sourcing and ensuring matched spring characteristics across all cylinders—a detail that directly affects consistent combustion stability and prevents individual cylinder misfires caused by uneven valve control.
RPM Series springs from PAC are manufactured to strict wire diameter and free-length tolerance, ensuring repeatability across the 16-piece set. This specification adherence is essential in high-performance engine building where spring frequency mismatch can induce resonance and accelerate fatigue failure under sustained high-rpm operation.
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