# Cylinder head gasket face distortion — maximum (NA6)

Canonical URL: https://miatatorque.com/spec/cylinder-head-distortion-limit-na6/

Applicability: NA 1990–1993 (B6) — Other years inferred from 1990 factory evidence.

Confidence: fsm

Distortion: 0.15 mm (0.006 in) max.

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": "cylinder-head-distortion-limit-na6",
  "name": "Cylinder head gasket face distortion — maximum (NA6)",
  "aliases": [],
  "applies_to": [
    {
      "gen": "NA",
      "years": [
        1990,
        1993
      ],
      "engines": [
        "B6"
      ],
      "note": "Other years inferred from 1990 factory evidence."
    }
  ],
  "kind": "non-torque",
  "value_text": "Distortion: 0.15 mm (0.006 in) max.",
  "procedure": {
    "notes": "Measure in all six factory-specified directions. Before resurfacing inspect valve-seat sinking, manifold contact surfaces, camshaft oil clearance and end play."
  },
  "confidence": "fsm",
  "sources": [
    {
      "source": "fsm-1990",
      "page": "B–48 (PDF p. 75)",
      "as_printed": "Distortion: 0.15mm (0.006 in) max.",
      "verified_years": [
        1990,
        1990
      ],
      "document": {
        "id": "fsm-1990",
        "tier": 1,
        "title": "1990 Mazda MX-5 Miata Workshop Manual",
        "part_number": "1193-10-89C",
        "covers": [
          {
            "gen": "NA",
            "years": [
              1990,
              1990
            ],
            "engines": [
              "B6"
            ]
          }
        ],
        "url": "https://archive.org/details/1990-mazda-mx-5-miata-workshop-manual_202411"
      }
    }
  ],
  "jobs": [],
  "system": "engine",
  "component": "inventory-pass-2026-10",
  "componentName": "Service measurements and fasteners",
  "sequence_diagrams": [],
  "url": "https://miatatorque.com/spec/cylinder-head-distortion-limit-na6/"
}
```