2.8L and 2.9L Bronco II plugs gap to .044 and torque to 15 ft-lbs; firing order is 1-4-2-5-3-6 with #1 at the front passenger side and a clockwise distributor.
Spark plugs are a 100,000-mile job in spec, but on a 30-plus-year-old Cologne V6 with marginal cooling and tired wires, replacing plugs every 30,000 miles is honest preventive work. New plugs almost always reveal a misfire problem you were learning to ignore — rough idle on cold start, a stumble off boost, a slight hesitation on the highway. The 2.8L (1984) and 2.9L (1986–1990) share the same plug spec: Motorcraft AGSF22C, gapped to .044", torqued to 15 ft-lbs. Autolite 25 and NGK 4929 are direct equivalents.
The hard part on a Bronco II isn't the plug — it's the access. The driver-side bank is buried under heater hoses, the AC compressor, and the dipstick tube. The passenger-side bank tucks behind the alternator. Plan on a swivel-socket adapter and a long extension. Don't fight the geometry with hand tools — the small 3/8" ratchet plus a wobble extension is the right approach.
Firing order is **1-4-2-5-3-6**, clockwise distributor rotation. Cylinder #1 is the front passenger side; the bank closer to the firewall is the driver bank (4-5-6). Pull and replace plugs one at a time so you don't cross-up the wires. Inspect each old plug as it comes out — light tan/brown is healthy. White and blistered means lean (vacuum leak or stuck-open EGR). Black and sooty means rich (cracked head dumping coolant, leaking injector, choked air filter). Oily plugs point at valve guides or rings. The 2.9L cracked-head failure mode often shows up here first as one cylinder running unusually wet.
Anti-seize a thin smear on the threads — these are aluminum heads and steel plugs that have lived through 30 Phoenix summers. Dielectric grease in the boot. Torque to 15 ft-lbs. If you don't have a torque wrench, hand-tight plus 1/16 turn is the field method for tapered-seat plugs, but a calibrated torque wrench is $40 and worth it.
| Part | Vendor | Est. price |
|---|---|---|
| Motorcraft AGSF22C (set of 6) | Motorcraft / RockAuto | ~$22 |
| Autolite 25 (set of 6) | Autolite | ~$16 |
| Anti-seize compound (small tube) | Permatex 81343 | ~$6 |
Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.