Showing specs for all NA & NB Miatas

Crankshaft main bearing oil clearance (NA8)

Oil clearance: 0.0008—0.0014 in (0.018—0.036 mm) Maximum: 0.004 in (0.10 mm)Oil clearance: 0.018—0.036mm {0.0008—0.0014 in} Maximum: 0.10mm {0.004 in}

Factory manualTaken from a Mazda factory workshop manual, with page citation.
Procedure

Remove oil/debris; fit grooved upper bearings and thrust bearings with oil grooves facing crankshaft. Place Plastigage axially; do not rotate crank. Install numbered caps in correct orientation and tighten in factory sequence/stages to 54–58 N·m. Read widest and narrowest Plastigage points for minimum and maximum clearance.

Applies to
  • NA 1994–1997 (BP) — Other years inferred from 1994 factory evidence.
  • Verified in: 1994 Mazda MX-5 Miata Workshop Manual