# Cylinder head manifold face distortion — maximum (NA6)

Canonical URL: https://miatatorque.com/spec/cylinder-head-manifold-face-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-manifold-face-distortion-limit-na6",
  "name": "Cylinder head manifold 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 each manifold contact surface in the four factory-specified directions; grind or replace the head if out of specification."
  },
  "confidence": "fsm",
  "sources": [
    {
      "source": "fsm-1990",
      "page": "B–49 (PDF p. 76)",
      "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-manifold-face-distortion-limit-na6/"
}
```