GM 18 Degree Koolsox

The GM 18 Degree Koolsox spark plug boot sleeve is an essential heat management accessory for engine builders, hot rodders, and mechanics working with high-performance GM ignition systems. Designed to protect spark plug boots from extreme underhood temperatures and radiant engine heat, this fiberglass cloth sleeve insulates critical ignition components and extends spark plug life in demanding applications. Whether you're tuning a street machine, competition engine, or restoring a classic GM platform, proper spark plug boot protection prevents misfires, voltage breakdown, and premature component failure in high-heat environments.

Constructed from durable fiberglass cloth material, the GM 18 Degree Koolsox boot sleeve features a straight design engineered specifically for 18-degree spark plug boots commonly found on GM small-block and big-block engines. The 5½-inch length provides full coverage of the boot stem where heat exposure is most critical, while the fiberglass composition offers superior thermal resistance compared to rubber or plastic alternatives. The black finish resists UV degradation and blends seamlessly into engine bays while maintaining structural integrity in temperatures that would degrade conventional ignition components. Installation is straightforward—simply slide the sleeve over the spark plug boot before assembly, requiring no tools or modifications.

This product is ideal for builders and enthusiasts working with carburetor-fed GM engines, tunnel-ram induction systems, and installations where engine compartment temperatures exceed 130°F. The GM 18 Degree Koolsox is particularly valuable in supercharged and turbocharged builds where radiant heat from exhaust manifolds and turbo housings accelerates boot degradation. Each sleeve is sold individually, so quantity depends on cylinder count and ignition configuration. Verify boot angle and diameter compatibility with your specific distributor cap before ordering to ensure proper fit and thermal protection.