The proper valve spring package is one of the most important components of any high performance engine. Serious street driven machines, hardcore racers and engine builders of performance cylinder heads, now have a brand new, extreme usage valve spring, steel retainer, valve lock and Viton seal kit that safely extends engine RPM and boosts performance capability.
This custom built PAC Racing 1521 based valvetrain kit features precision wound, nitrided and heat-set, small diameter, dual valve springs with the required seat and open load pressure plus total spring travel to accommodate camshafts with aggressive lobes and gross valve lifts up to .650”, depending on the installed height. The nitrided dual valve springs contained in each kit are carefully tension matched and all supplied components are included and ready to install with no machining.
The kit contains CNC machined, chromemoly alloy spring retainers, engineered to deliver maximum strength and durability. The hardened and machined spring locators were designed to accurately locate the inner spring to the valve guide boss, preventing abrasion and scuffing when using aluminum cylinder heads. Precision machined & hardened 4140 steel alloy 7-degree valve locks are provided for superior valve stem holding reliability. Premium quality, Viton® steel reinforced valve stem seals are used for correct valve stem lubrication and oil control.
The PAC Racing 1521 is an extreme duty valve spring designed for lightweight LSx style valvetrain used in a high RPM or certain forced induction engine. Will fit most aftermarket cylinder heads with small 1.300" diameter dual spring packages. PAC Racing's proprietary Pacalloy material, nitrided post-processing and ovate wire construction are used.
HOW TO ORDER:
1) Choose your valve stem diameter: 11/32" - 5/16" or 8mm
2) Choose your valve seal diameter: .500" or .531" guide top
3) Choose your valve guide diameter: .500" or .563" guide base
The standard spring kit contains lightweight chromemoly retainers but you can upgrade to the optional titanium or tool steel retainers. Certain aftermarket cylinder heads may require a custom built version of this kit. Email for more information on custom cylinder head applications.
PAC RACING 1521 VALVE SPRING SPECS:
PART NUMBER: FTI-GEN7-K1