The 351 engine came in a couple of variations. They were referred as the Windsor and Cleveland 351 engines. The engines were named after where they were produced, Windsor Ontario or Cleveland Ohio. They are not the same engines though. The Windsor block is a continuation of the 302 engine. Where the Cleveland engine is considered more of a large block engine although both has the same displacement.
 | 351 "C" 4V 1970-1973 Cleveland | 351 "W" 4V 1969 Windsor | 351 "R" 4V 1971-1972 Boss 351-HO | 351 "H" 2V 1969 |
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| Engine Type | 8 cylinder 90 degree, Overhead Valves (OHV) | 8 cylinder 90 degree, Overhead Valves (OHV) | 8 cylinder 90 degree, Overhead Valves (OHV) | 8 cylinder 90 degree, Overhead Valves (OHV) |
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| Displacement | 351 cu.inches (CID) | 351 cu.inches (CID) | 351 cu.inches (CID) | 351 cu.inches (CID) | ||
| Maximum torque | 380 lbs./ft. @ 3,400 RPM | 380 lbs./ft. @ 3,400 RPM | 370 lbs./ft. @ 4,000 RPM (1971) 275 lbs./ft. @ 6,000 RPM | 355 lbs./ft. @ 2,600 RPM |
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| Maximum Horsepower | 300 BHP @ 5,400 | 300 BHP @ 5,400 RPM | 330 BHP @ 5,400 RPM (1971) 275 BHP @ 6,000 RPM (1972) | 250 BHP @ 4,600 RPM |
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| Firing Order | | 1-5-4-2-6-3-7-8 |
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| Bore & Stroke | 4.00" X 3.50" | 4.00" X 3.50" | 4.002" x 3.50" | 4.00" X 3.50" |
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| Compression Ratio | 11.0:1 | 11.0:1 | 11.5:1 (1971) 9.2:1 (1972) | 9.51:1 |
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| Mains | 2-bolt | 2-bolt | 4-bolt | 2-bolt | ||
| Carburetor | Autolite 4300-A (4V) | Autolite 4300-A (4V ) Squarebore automatic choke | Autolite 4300-D (4V) Squarebore
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| Size of Carburetor | ||||||
| Fuel | premium gas | premium gas | super premium (1971) premium gas (1972) | regular gas |
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| Intake Manifold | cast iron | cast iron | aluminum (1971) cast iron (1972) | cast iron |
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| Valve train | hydraulic lifters | hydraulic lifters | solid & adjustable lifters | hydraulic lifters | ||
| Intake | 2.185"-2.195" | 2.185"-2.195" | 2.184"-2.195"" | 1.9025"-1.9175" | ||
| Exhaust | 1.7045"-1.7145" | 1.7045"-1.7145" | 1.7045"-1.7145" | 1.533"-1.548" | ||
| Distributor | single point vacuum advance | single point vacuum advance | dual point vacuum advance | single point vacuum advance |
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| Point Gap | .017" | |||||
| Initial Ignition Timing | 6 degrees | |||||
| Dwell @ idle RPM | 24-29 (manual) 26-31 (auotmatic) |
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| Spark Plugs | Autolite AF-42 | Autolite AF-42 | Autolite ARF-42 | Autolite ARF-42 | ||
| Spark Plug Gap | .032"-.036" | |||||
| Long Block Weight in lbs. | 530 | 530 | 530 | 530 | ||
| Emission Controls | IMCO (with Automatic, only NOx system) California IMCO (with automatic, only) | IMCO (with Automatic, only NOx system) California IMCO (with automatic, only) | NOx California | IMCO (with Automatic, only NOx system) California IMCO (with automatic, only) |
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| RPM Rev Limiter | 6,050-6,150 RPM | |||||
| 1970 - The 351 engine was used in Mercury Cougars & 1970 1/2 - The Ford Falcons had an optional 351 engine. 1971 - The 351 was available for use in the Mercury 1971-1973 - The HO (High Output) Boss 351 engine was |
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