# Valve head margin thickness (NA8)

Canonical URL: https://miatatorque.com/spec/valve-head-margin-na8/

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

Confidence: fsm

Margin thickness
IN: 0.9mm {0.035 in}
EX: 1.0mm {0.039 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-head-margin-na8",
  "name": "Valve head margin thickness (NA8)",
  "aliases": [],
  "applies_to": [
    {
      "gen": "NA",
      "years": [
        1994,
        1997
      ],
      "engines": [
        "BP"
      ],
      "note": "Other years inferred from 1994 factory evidence."
    }
  ],
  "kind": "non-torque",
  "value_text": "Margin thickness\nIN: 0.9mm {0.035 in}\nEX: 1.0mm {0.039 in}",
  "procedure": {
    "notes": "Source gives these margin thicknesses without an explicit minimum label; inspect each valve and replace if necessary."
  },
  "confidence": "fsm",
  "sources": [
    {
      "source": "fsm-1994",
      "page": "B–48 (PDF p. 85)",
      "as_printed": "Margin thickness\nIN: 0.9mm {0.035 in}\nEX: 1.0mm {0.039 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-head-margin-na8/"
}
```