Factory 351 Windsor — Specs and Swap Value
The 351 Windsor is the factory big-cube option — only installed in 1976 and 1977 Broncos. These trucks carry a premium and the engine is worth keeping. A 4-barrel carburetor, a real ignition, and a free-flowing exhaust wake it up substantially without touching the bottom end. As a swap into a non-351 truck it is only worth the trouble if you are building a heavy trail rig or already own the engine.
Ford offered the 351 Windsor (5.8L) in the Bronco for the final two model years. Net output was rated around 154 hp in the smog era — modest on paper, but the point of the 351W has never been peak horsepower. It makes meaningfully more torque than the 302, roughly 280 lb-ft versus about 220, and torque is what moves a heavy 4x4 on tall gears and big tires.
The 351W shares the 302's small-block architecture but uses a taller deck and a longer 3.50" stroke (versus 2.87"). It accepts the same accessories, the same motor mounts, and most of the same bolt-on aftermarket, which is why it drops into the Bronco's engine bay the same way a 302 does.
A loaded early Bronco on 33–35" tires asks for low-rpm grunt, not top-end power. The 351W's longer stroke delivers that — it pulls a hill at lower rpm and lugs less than a 302 in the same truck. Paired with the Dana 20's modest 2.03:1 low range (see the Dana 20 transfer case guide) and appropriate axle gearing from the gear ratio guide, the extra torque is what keeps you out of constant downshifting on the trail.
The factory smog-era 2-barrel and weak ignition leave power on the table:
- Carburetor and intake. The factory 2-bbl is the biggest restriction. An Edelbrock Performer 351W intake (P/N 2181) topped with a 600 cfm Performer carburetor (P/N 1405) is the classic mild combination — expect 25–35 hp and a noticeable improvement in throttle response. Budget about $550–$600 for the pair.
- Ignition. Convert the points to a Pertronix Ignitor II (the 351W unit is P/N 91281) for stable timing and no maintenance. The broader tune-up procedure — timing, dwell, vacuum advance, carburetor adjustment — is in the ignition and carburetor tune-up guide, and it applies the same way to the 351W as to the 302.
- Exhaust. A set of shorty headers and 2.5" dual exhaust frees up more usable power than any single carburetor change, and it lets the bigger engine breathe out as well as in.
The 351W carries more mass and makes more heat than the 302, and the early Bronco's small engine bay and marginal factory cooling were never generous to begin with. Low-speed crawling in summer is where these trucks overheat. Keep the factory 7-blade steel clutch fan and shroud intact, and plan a cooling upgrade alongside any 351 — a higher-capacity radiator and correct fan setup, covered in the cooling system upgrade guide, is the difference between a truck you can wheel on a hot day and one that boils over in the rocks.
If you are putting a Ford V8 into a non-351 Bronco from scratch, the carbureted 302 is cheaper, lighter on the front axle, and plenty for most builds — its details are in the factory 302 V8 guide. The 351W swap only earns its keep when you need the torque for a heavy, big-tire rig or you already have a good 351 core. If your priority is modern cold-start and altitude reliability rather than displacement, a fuel-injected 5.0L is a different path entirely — see the 302 HO / EFI swap guide.
Why it works
- factory fitment in 76–77 (no swap required)
- significantly more torque than the 302
- shares the 302's mounts, accessories, and much of its aftermarket
- responds strongly to carburetor, ignition, and exhaust work
Trade-offs
- factory-installed in only two model years; good cores are getting scarce
- heavier than the 302, adding front-end weight
- runs hotter — a cooling upgrade is effectively mandatory
- smog-era factory tune leaves it dull until the carburetor and ignition are addressed
Tools required
- timing light
- vacuum gauge
- carburetor tuning tools
Parts
| Part | Vendor | Est. price |
|---|---|---|
| Edelbrock Performer 600 cfm 4-bbl carburetor | Edelbrock | ~$360 |
| Edelbrock Performer 351W intake manifold | Edelbrock | ~$230 |
| Pertronix Ignitor II for 351W | Pertronix | ~$125 |
| Shorty headers, 351W (ceramic-coated pair) | Hedman / Patriot | ~$320 |
Sources
Related
- Factory 302 V8 — Specs, Carb, and Tune
- 5.0L HO / EFI 302 Swap
- All Ford Bronco guides & tools
- Browse the full DIY database
Written and maintained by an AZ wheeler and driveway wrencher. How we source guides. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.