Showing specs for all NA & NB Miatas

Valve guide inner diameter (NA6)

Inner diameter IN: 0.2366–0.2374 in (6.01–6.03 mm) EX: 0.2366–0.2374 in (6.01–6.03 mm)Inner diameter IN: 6.01–6.03 mm (0.2366–0.2374 in) EX: 6.01–6.03 mm (0.2366–0.2374 in)

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

Measure the inner diameter of each valve guide at the factory-indicated points.

Applies to
  • NA 1990–1993 (B6) — Other years inferred from 1990 factory evidence.
  • Verified in: 1990 Mazda MX-5 Miata Workshop Manual