# Valve stem diameter (NA8)

Canonical URL: https://miatatorque.com/spec/valve-stem-diameter-na8/

Applicability: NA 1994–1997 (BP) — Other years inferred from 1994 factory evidence.

Confidence: fsm

Diameter
IN: 5.970—5.985mm {0.2351—0.2356 in}
EX: 5.965—5.980mm {0.2349—0.2354 in}
Minimum
IN: 5.920mm {0.2331 in}
EX: 5.915mm {0.2329 in}

Always confirm against your factory manual. Match every restriction and follow all stages and procedure notes. Disputed claims must not be automatically resolved. The complete record below preserves every printed unit, source claim and procedure.

```json
{
  "id": "valve-stem-diameter-na8",
  "name": "Valve stem diameter (NA8)",
  "aliases": [],
  "applies_to": [
    {
      "gen": "NA",
      "years": [
        1994,
        1997
      ],
      "engines": [
        "BP"
      ],
      "note": "Other years inferred from 1994 factory evidence."
    }
  ],
  "kind": "non-torque",
  "value_text": "Diameter\nIN: 5.970—5.985mm {0.2351—0.2356 in}\nEX: 5.965—5.980mm {0.2349—0.2354 in}\nMinimum\nIN: 5.920mm {0.2331 in}\nEX: 5.915mm {0.2329 in}",
  "procedure": {
    "notes": "Measure each stem at the factory-specified points."
  },
  "confidence": "fsm",
  "sources": [
    {
      "source": "fsm-1994",
      "page": "B–48 (PDF p. 85)",
      "as_printed": "Diameter\nIN: 5.970—5.985mm {0.2351—0.2356 in}\nEX: 5.965—5.980mm {0.2349—0.2354 in}\nMinimum\nIN: 5.920mm {0.2331 in}\nEX: 5.915mm {0.2329 in}",
      "verified_years": [
        1994,
        1994
      ],
      "document": {
        "id": "fsm-1994",
        "tier": 1,
        "title": "1994 Mazda MX-5 Miata Workshop Manual",
        "covers": [
          {
            "gen": "NA",
            "years": [
              1994,
              1997
            ],
            "engines": [
              "BP"
            ]
          }
        ],
        "note": "Mazda's base manual for 1994–97; later model years got supplements, which we haven't checked yet."
      }
    }
  ],
  "jobs": [],
  "system": "engine",
  "component": "inventory-pass-2026-10",
  "componentName": "Service measurements and fasteners",
  "sequence_diagrams": [],
  "url": "https://miatatorque.com/spec/valve-stem-diameter-na8/"
}
```