The 5.0 HO (Fox-body 302) is the most cost-effective real power upgrade for a carbureted early Bronco. Bolt a dual-plane intake, shorty headers, and a 600 cfm carb onto an HO long block and you are making 240-260 hp for well under $3,000 — and because it is still a 302 Windsor, it drops onto existing Bronco V8 mounts. Build it carbureted for a clean install, or retain the factory EFI if you want modern cold-start and altitude behavior and can accept 20-30 hours of harness work. Three details decide whether this swap goes smoothly: the oil pan, the balance weight, and the firing order.
The Fox-body 5.0L HO (High Output) ran from 1982-1995 in the Mustang and is the donor of choice because cores are cheap and everywhere. The block is a 302 Windsor, so it bolts where any Bronco 302 already lives and mates to the same small-block Ford bellhousing pattern your existing transmission uses.
The HO is a hot-cammed, better-breathing version of the same 302 covered in the factory V8 guide. What to look for when shopping a donor:
Balance weight. Every 302 from 1982 forward is 50 oz-in externally balanced; 1981 and earlier 302s are 28 oz-in. The flexplate or flywheel and the harmonic balancer both carry the counterweight, so an HO long block bolted to your old Bronco's 28 oz-in flexplate will vibrate badly and eventually crack something. Buy the matching 50 oz-in flexplate or flywheel and use the donor's balancer.
Firing order. The HO camshaft uses firing order 1-3-7-2-6-5-4-8, not the 1-5-4-2-6-3-7-8 of a standard 302. Wire the distributor cap to the HO order if you keep the HO cam. Installing a non-HO replacement cam flips you back to the standard order. Getting this wrong produces an engine that fires, runs terribly, and sends people chasing carburetor problems for a weekend.
Oil pan. The Fox-body Mustang pan is a rear-sump design; the early Bronco's front crossmember demands a front-sump truck pan with the matching pickup tube and dipstick. Swap the pan on the stand before the engine goes in the truck — discovering the clearance problem with the engine hanging on the hoist costs an afternoon.
For most early Broncos, carbureted is the path of least resistance and the one most owners should choose. Drop the HO long block onto the existing 302 mounts and add:
That combination gives 240-260 hp with a street tune and good idle quality on the dual-plane manifold. Total parts, with a $900 core, land near $2,200-2,600. Set it up per the tune-up guide once it runs, and run a compression and leak-down test on the core before you spend a dollar on top-end parts.
If the donor is a 1988-1993 Mustang, you can keep the mass-air EFI rather than carbureting it. That means retaining the donor ECU, engine harness, MAF, injectors, and TFI distributor, then stripping the harness of A/C, emissions, and body branches until only the engine circuits remain. Plan 20-30 hours for a first-time harness cleanup, and budget for the supporting systems the carb build does not need:
The payoff is genuinely better cold starts, better fuel economy, and automatic altitude compensation — meaningful if you wheel above 6,000 feet. If a turn-key injected setup is the actual goal, weigh this against a purpose-built aftermarket EFI conversion, which is designed for retrofit rather than adapted from a car harness and often costs less in hours than it does in dollars.
| Item | Carbureted | EFI retained |
|---|---|---|
| HO long block core | $600-1,200 | $800-1,500 (complete takeout) |
| Intake + carb | $660 | — |
| Ignition (MSD/Duraspark) | $210-320 | included with donor |
| Front-sump pan, pickup, dipstick | $150 | $150 |
| 50 oz-in flexplate/flywheel | $120 | $120 |
| Headers + exhaust | $600-800 | $600-800 |
| Fuel system | $80 (mech pump) | $450-700 (HP pump, return line, sender) |
| Wiring | $50 | $200-400 |
| Cooling upgrade | $400-700 | $400-700 |
| Total | $1,800-2,900 | $2,900-4,500 |
| Part | Vendor | Est. price |
|---|---|---|
| Ford 5.0L HO long block (Fox-body donor) | Salvage/Core | ~$900 |
| Edelbrock Performer 289/302 dual-plane intake | Edelbrock | ~$260 |
| Edelbrock Performer 600 cfm carburetor, manual choke | Edelbrock | ~$400 |
| Hooker shorty headers for 302 in early Bronco | Hooker | ~$280 |
| MSD 6AL ignition box | MSD | ~$210 |
| Front-sump truck oil pan, pickup, and dipstick | Ford / Milodon | ~$150 |
| 50 oz-in balanced flexplate or flywheel | Ford Racing / Various | ~$120 |
| Bronco V8 motor mounts (if swapping from I6) | Various | ~$120 |
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.
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