Showing specs for all NA & NB Miatas

Spark plug gap (NA 1.8)

1.0–1.1 mm (0.040–0.043 in)

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

Factory plug gap for the naturally aspirated engine; the Mazdaspeed plug has a separate smaller gap.

Applies to
  • NA 1994–1997 (BP) — Other years in this family inferred from 1994 factory evidence with owner approval; actual-year verification is separate.
  • Verified in: 1994 Mazda MX-5 Miata Workshop Manual
Sources
  • 1994 Mazda MX-5 Miata Workshop ManualTier 1
    Page G–18 (PDF p. 325)
    Printed: “Plug gap: 1.0—1.1mm {0.040—0.043 in}”

Also in Additional factory manual gap audit