SBC LT1 D-Port Header Gasket

The SBC LT1 D-Port Header Gasket by Mr. Gasket is a precision-engineered exhaust sealing component designed for small-block Chevrolet and LT-series engine swaps, particularly those fitted with modern D-port cylinder heads. Built for the 1992–97 generation of GM LT platforms, this gasket pair addresses one of the most critical leak points in a high-performance engine build: the interface between the header flange and the D-port head casting. Whether you're assembling a street engine, a weekend warrior, or a restomod project, a quality header gasket ensures consistent exhaust scavenging and prevents costly coolant or oil seepage that can compromise engine longevity and performance.

This gasket features a steel-core laminate construction with Ultra-Seal facing technology, a proven design that withstands thermal cycling and exhaust manifold vibration without delamination or blow-out. The 1.520 × 1.510 inch D-port port openings are precision-cut to match OEM GM head castings, ensuring zero misalignment and maximum sealing surface contact. Steel-core laminates resist gas permeability far better than soft asbestos alternatives, maintaining integrity across repeated heat cycles from ambient to 1,400°F+. The compact profile and lightweight construction (0.25 lbs per pair) make installation straightforward on tight header flanges while delivering the durability demanded by modern fuel-injection and ignition systems that expose gaskets to higher combustion temperatures.

Mechanics and engine builders working with Gen II and Gen III small-block platforms rely on Mr. Gasket's D-port header gaskets to prevent exhaust leaks that reduce scavenging efficiency and create drivability issues. This pair is essential during any header installation, swap, or cylinder head replacement on LT1-equipped vehicles. Proper installation requires clean flange surfaces, appropriate torque sequencing (typically 18–25 ft-lbs), and compatible header bolts; never reuse old gaskets or overtighten, as laminate gaskets require even clamping pressure. For anyone building or rebuilding an SBC/LT platform, the SBC LT1 D-Port Header Gasket is a non-negotiable wear item that preserves engine performance and reliability.