Cometic MLS Head Gasket 84mm Bore .056in - NA8/NB1 Miata (94-00)

The Cometic C4568-056 is a multi-layer steel (MLS) cylinder head gasket for the Mazda 1.8L BP engine (BP-ZE / BP-4W) with an 84 mm bore (1 mm over the stock 83 mm) and a compressed thickness of .056 in. Cometic lists it for the 1994-1997 Mazda Miata (NA, 1.8L) and the 1999-2000 Mazda Miata (NB1). Gasket thickness is one of the variables used to set compression ratio and piston-to-head clearance in a built engine.

• Sized for an 84 mm bore, for BP engines bored 1 mm over the stock 83 mm; match the gasket bore to the engine's finished bore size
• Compressed thickness .056 in, well over the 0.032 in factory 1994-2000 metal gasket; a thicker gasket adds combustion-chamber volume and lowers compression; Cometic does not publish a compression ratio for this gasket, so calculate it for your build
• 5-layer MLS (multi-layer stainless steel) construction; Cometic uses five layers on its thicker gaskets
• Outer stainless steel layers carry a .001 in Viton rubber coating; installed dry, without additional sealant (Cometic says extra sealer can hinder sealing)
• Requires smooth, flat and true head and block deck surfaces; Cometic recommends a surface finish of 50 Ra or finer
• Made to order by Cometic; use the head bolt (fastener) manufacturer's torque values

Fitment: 1994-1997 Mazda Miata (NA, 1.8L BP-ZE) and 1999-2000 Mazda Miata (NB1, 1.8L BP-4W). Not for 2001-2005 Miata (NB2, including the 2004-2005 Mazdaspeed): those heads have different coolant passages and Cometic sells separate gaskets for them (C4983 84 mm and C4984 85 mm bore). Not for the 1990-1993 1.6L (B6). If the head and block come from different years, match the gasket to the head.

Part number: Cometic C4568-056

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