# Valve spring free length — standard and minimum (NA6)

Canonical URL: https://miatatorque.com/spec/valve-spring-free-length-na6/

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

Confidence: fsm

Free length
Standard
IN: 48.0 mm (1.890 in)
EX: 48.3 mm (1.902 in)
Minimum
IN: 47.0 mm (1.850 in)
EX: 47.3 mm (1.862 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-spring-free-length-na6",
  "name": "Valve spring free length — standard and minimum (NA6)",
  "aliases": [],
  "applies_to": [
    {
      "gen": "NA",
      "years": [
        1990,
        1993
      ],
      "engines": [
        "B6"
      ],
      "note": "Other years inferred from 1990 factory evidence."
    }
  ],
  "kind": "non-torque",
  "value_text": "Free length\nStandard\nIN: 48.0 mm (1.890 in)\nEX: 48.3 mm (1.902 in)\nMinimum\nIN: 47.0 mm (1.850 in)\nEX: 47.3 mm (1.862 in)",
  "procedure": {
    "notes": "Inspect each spring for cracks and damage; replace if necessary."
  },
  "confidence": "fsm",
  "sources": [
    {
      "source": "fsm-1990",
      "page": "B–52 (PDF p. 79)",
      "as_printed": "Free length\nStandard\nIN: 48.0mm (1.890 in)\nEX: 48.3mm (1.902 in)\nMinimum\nIN: 47.0mm (1.850 in)\nEX: 47.3mm (1.862 in)",
      "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/valve-spring-free-length-na6/"
}
```