Moroso Racing Radiator Cap 14-18 PSI Low Pressure | 63316

Stock radiator caps are a compromise part — set low enough to work across a wide range of cars, not tuned for the heat a performance engine actually generates. This Moroso cap runs a 14-18 lb pressure rating, raising your system's boiling point so coolant stays liquid and doing its job even when underhood temps climb during hard driving.

Inside, it uses a stainless steel spring instead of the standard-issue steel spring that loses tension over time, so the pressure setting stays accurate cap after cap, season after season. The spring retainer is solid brass, and the cap body is a six-sided (hex) design that's easier to grip and tighten than the smooth round caps most stock systems use — useful when you're working in a tight engine bay with gloves on.

Fitment: Standard-size radiator filler necks, including Moroso filler neck part numbers 63420, 63465, 63466, 63467, 63485, 63486, 63650, 63651, 63656, 63730, 63740, and 63745.
Note: This cap fits standard-size filler necks generally — not vehicle-specific. Confirm your radiator or filler neck uses a standard-size opening before ordering.

Key features and benefits

• 14-18 lb pressure rating raises coolant boiling point for better heat management under load
• Stainless steel spring holds an accurate pressure setting over time, unlike standard caps that weaken
• Solid brass spring retainer
• Six-sided (hex) cap design for easier gripping and tightening
• Fits standard-size radiator filler necks across multiple applications