{
  "subject": "MG Midget 1500 PE94J engine family",
  "status": "partial_factory_dimensions_not_complete_manufacturing_geometry",
  "primary_source": {
    "title": "MG Midget 1500 workshop manual, general specification data",
    "url": "https://www.spridgets.de/downloads/Midget%201500%20WH%20Teil%201.pdf",
    "pdf_pages": [11, 12]
  },
  "all_dimensions_mm": {
    "bore_nominal": 73.7,
    "stroke_nominal": 87.5,
    "crank_throw_radius_derived": 43.75,
    "connecting_rod_center_distance": [145.9, 146.1],
    "crank_main_journal_diameter": [58.713, 58.725],
    "crankpin_journal_diameter": [47.625, 47.638],
    "gudgeon_pin_outer_diameter": [20.63, 20.64],
    "camshaft_front_rear_journal_diameter": [49.93, 49.95],
    "camshaft_center_journal_diameter": [49.9, 49.92],
    "inlet_valve_head_diameter": [34.97, 35.01],
    "exhaust_valve_head_diameter": [29.66, 29.76]
  },
  "configuration": {
    "cylinders": 4,
    "displacement_cc": 1493,
    "firing_order": [1, 3, 4, 2],
    "valve_operation": "overhead valves, pushrod",
    "main_bearings": 3
  },
  "photo_scale_anchors": [
    {
      "component": "rocker cover gasket footprint",
      "dimensions_mm": {"length": 360, "width": 110, "thickness": 6},
      "part_cross_reference": "AJM414 / AJUSA 11007400",
      "source": "https://www.autodoc.pl/ajusa/7245892",
      "observed_in_user_photos": ["IMG_6797.HEIC", "IMG_6853.HEIC", "IMG_6856.HEIC"],
      "status": "supplier dimensions for matching replacement gasket; visible cover footprint is an approximation"
    },
    {
      "component": "rocker-cover oil filler cap candidate",
      "dimensions_mm": {"diameter": 58},
      "source": "https://www.limora.com/en/oil-filler-cap/2149/",
      "observed_in_user_photos": ["IMG_6856.HEIC"],
      "status": "cross-check only; pictured cap finish differs from listed replacement, exact part unconfirmed"
    }
  ],
  "variant_caution": "Midget FP and Spitfire FM engines share a basic family but differ in fuel pump, distributor and some small parts. Check the fitted engine prefix and North American emissions equipment before assigning accessory geometry.",
  "missing_for_accurate_cad": [
    "cylinder_center_spacing",
    "block_exterior_and_deck_coordinates",
    "head_and_combustion_chamber_surfaces",
    "port_centers_and_profiles",
    "bolt_hole_coordinates_and_thread_specs",
    "sump_exterior_and_internal_pickup_geometry",
    "mounting_and_gearbox_interface_coordinates",
    "car_specific_intake_exhaust_carburetor_and_emissions_geometry"
  ]
}