How much horsepower does a 1970 M-code 351 Cleveland 4V 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: 5200 rpm.
The best modern dyno sheet for a 1970 4V is not a restoration — it is Lykins Motorsports' 2023 build, which kept the factory 4V heads unported and the factory cast-iron 4V intake and still made 433 hp and 428 lb-ft on pump gas at under 10:1. The only thing separating that engine from a rebuilt survivor was a mild hydraulic roller and a proper carburetor.
That tells you what a stock 1970 4V is and is not. The heads and intake were never the problem; a 4V port flows more than the factory cam could ever use. The 1970 M-code hydraulic cam (D0AZ-6250-C, 196/204 at .050, .427"/.453") and the 470-cfm Autolite 4300 are what hold a stock 4V to the low 300s at the flywheel. The factory rated it 300 gross; on a modern STD-corrected engine dyno with stock manifolds the number up top is the right neighborhood.
If you are rebuilding one and want it stock-looking but not stock-feeling, the Lykins recipe is the template: leave the castings alone, put a modern cam under them, feed it with a carburetor sized for 351 inches, and set the timing on a dyno.
The M-code is the four-barrel Cleveland: big-port 4V heads, the factory hydraulic cam, an Autolite 4300 and the cast iron 4V manifold. Ford rated it 300 gross in 1970 and 285 in 1971.
Those enormous 4V intake ports are the whole character of this engine. They flow beautifully at high lift and they are lazy down low, which is why a 4V car feels flat off idle next to a 2V and then pulls away from it up top.
If your car came with a 4V and you drive it on the street, read the head comparison page before you spend money on cylinder heads.
The build
| Block | Factory 351C 2-bolt main (stock) |
|---|---|
| Crank | Stock cast iron — 3.50" stroke (351 ci) |
| Rods | Stock I-beam (factory) — builders' guide ~450 HP |
| Pistons | Generic flat top (0cc) |
| Head gasket | OEM compressed (.040") — neutral |
| Cylinder heads | 4V open chamber (75.6cc) — 70s CJ/Q-code |
| Porting | As-cast / stock |
| Camshaft | Stock 351C-4V (M-code, D0AZ-6250-C) — 268/280 adv · 196/204 @.050 · .427"/.453" |
| Valve springs | Stock 4V / Cobra Jet springs |
| Rocker arms | Stock stamped 1.73 rockers |
| Intake manifold | Stock 4V cast iron — factory 4bbl |
| Carburetor | Autolite 4300 4bbl — stock 351C-4V (470 cfm) — out of production since 1974, reman/NOS only |
| 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 |