How much horsepower does a 1970 H-code 351 Cleveland have?
Engine dyno, as configured — flywheel horsepower. Standard test config: stock manifolds through 18" of pipe, air cleaner lid flipped, no accessories driven. Factory SAE net ratings are measured as‑installed and read 15–25% lower. Rev ceiling for this combination: 5000 rpm.
The H-code is the two-barrel Cleveland — open-chamber 2V heads, the mild factory hydraulic cam, an Autolite 2100 two-barrel and cast iron manifolds. Ford rated it 250 horsepower gross in 1970.
Simulated as it left the factory it comes out under the advertised gross figure, and that gap is the whole story of 1970s ratings: gross numbers were taken with no accessories and optimistic timing. The way a number is measured matters as much as the number.
Worth knowing what this engine is not. The 2V head is its own casting, not a detuned 4V — different ports, different chambers, different valves. That is why a 2V and a 4V respond so differently to the same camshaft.
The build
| Block | Factory 351C 2-bolt main (stock) |
|---|---|
| Crank | Stock cast iron — 3.50" stroke (351 ci) |
| Rods | Stock I-beam (factory) — to ~450 HP |
| Pistons | Generic OEM-style dish (−7cc) |
| Head gasket | OEM compressed (.040") — neutral |
| Cylinder heads | 2V US open chamber (75cc) — the common head |
| Porting | As-cast / stock |
| Camshaft | Stock 2V — hyd flat tappet (D0AZ-6250-B, .400" lift) |
| Valve springs | Stock 2V springs |
| Rocker arms | Stock stamped 1.73 rockers |
| Intake manifold | Stock 2V cast iron — factory 2bbl flange |
| Carburetor | Autolite 2100 2bbl — stock 351C-2V · 1.21" venturi · 351 cfm @3.0" (≈250 4bbl-equiv) |
| Exhaust | Stock manifolds + 18" pipe — DYNO STANDARD |
| Ignition | Stock breaker points — floats ~5,200 rpm |
| Fuel | Pump 87 octane |
| Air cleaner | Stock air cleaner, LID FLIPPED — DYNO STANDARD |