Remflex Square-Port Exhaust Header Gasket for Ford Windsor V8s 1-1/8"x1-1/2" — Flexible Graphite, 1/8" Thick (Pair)

Remflex 3003 is a 100% flexible graphite square-port exhaust header gasket engineered to seal warped flange faces on Ford Windsor V8 engines (1-1/8" x 1-1/2").

When aluminum cylinder heads meet steel headers or manifolds, repeated heating and cooling can create small but performance-limiting gaps at the flange surfaces. The Remflex 3003 gasket is built from pure flexible graphite at a standard 1/8" thickness and designed to compress half its thickness to conform to imperfect or corroded mating surfaces. Sold in pairs, this gasket fits common Ford Windsor applications including 302 and 351 engines and works with both stock manifolds and aftermarket headers.

How does this gasket stop exhaust leaks on Windsor V8s?

The Remflex 3003 fills irregularities between the head and header with a highly compressible graphite material that conforms to pits and warping. Because it’s 100% flexible graphite with no rubber binders, the gasket maintains sealing performance through many heat cycles without drying out or shrinking. Its 1/8" thickness is engineered to crush about 50%, so it fills gaps up to approximately 1/16".

• Material: pure flexible graphite resists high temperatures and thermal cycling
• Thickness: standard 1/8" designed to compress ~50%
• Gap capacity: conforms to flange irregularities up to ~1/16"
• Fitment: matches 1-1/8" x 1-1/2" square-port openings used on Windsor V8s

Which engines and flange types will this gasket fit?

The Remflex 3003 was specified for square-port Ford V8 applications and fits 1-1/8" x 1-1/2" port openings commonly found on 302 (’81–’95) and 351 Windsor (’69–’97) cylinder heads. It works with both cast-iron manifolds and aftermarket steel headers where dissimilar metals often create sealing challenges. Always compare port dimensions and bolt pattern before installation.

• Compatible engines: Ford 302 (’81–’95) and 351 Windsor (’69–’97)
• Port size: 1-1/8" width × 1-1/2" height square port
• Applications: stock manifolds or aftermarket headers
• Sold quantity: 2 per set (enough for one side)

What makes Remflex graphite different from composite or rubber gaskets?

Remflex gaskets are free of rubber binders and composite fillers, so they won’t dry, harden, or delaminate under repeated heat exposure. The flexible graphite construction remains forgiving across temperature swings and keeps bolt torque stable over time, reducing the need for frequent retorquing. That durability helps maintain a reliable exhaust seal even when mating surfaces are uneven or warped.

• No rubber binders—won’t shrink or harden with age and heat
• Maintains seal through many thermal cycles
• Compressibility accommodates flange warpage and pitting
• Durable against exhaust temperatures typical of header/manifold use

Who is this for? Remflex 3003 is aimed at mechanics, restorers, and DIY enthusiasts working on Ford Windsor V8 engines who need a dependable exhaust seal between aluminum heads and steel headers or manifolds. If you’re replacing a leaking header gasket, upgrading to aftermarket headers, or addressing flange warpage without milling surfaces, this graphite gasket offers a long-lasting, low-maintenance solution. Verify port size and bolt pattern before purchase to ensure a correct fit.