Cometic MLS Head Gasket 83mm Bore .027in - NA8/NB1 Miata (94-00)

The Cometic C4560-027 is a multi-layer steel (MLS) cylinder head gasket for the Mazda 1.8L BP engine (BP-ZE / BP-4W) with the stock 83 mm bore and a compressed thickness of .027 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 the 83 mm bore, the stock bore size of the 1.8L BP engine
• Compressed thickness .027 in, thinner than the 0.032 in factory 1994-2000 metal gasket; a thinner gasket reduces combustion-chamber volume, raising compression and reducing piston-to-head clearance; Cometic does not publish a compression ratio for this gasket, so calculate it for your build
• 3-layer MLS (multi-layer stainless steel) construction
• 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 C4560-027

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