Moroso Racing Radiator Cap 27-29 PSI High Pressure | 63328

This is Moroso's higher-pressure racing cap, built for cooling systems that need more headroom than a standard 14-18 lb cap provides. Running at 27-29 lbs, it pushes your coolant's boiling point up further, buying you more margin before you're fighting boil-over on track or under sustained hard load.

Like the rest of Moroso's radiator cap line, it uses a stainless steel spring that holds its pressure setting over time instead of weakening the way a standard steel spring does, and a solid brass spring retainer that won't rust or seize. The six-sided hex cap design makes it easier to grip and tighten securely, even with gloves on in a tight engine bay.

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. This is a high-pressure application; make sure the rest of your cooling system (hoses, radiator, filler neck) is rated to handle 27-29 lb before installing.

Key features and benefits

• 27-29 lb pressure rating pushes coolant boiling point higher for demanding, high-heat applications
• Stainless steel spring holds an accurate pressure setting over time without rusting
• Solid brass spring retainer
• Six-sided (hex) cap design for easier gripping and tightening
• Fits standard-size radiator filler necks across multiple applications