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The Ford 351M engine is a part of Fords 335-series family of engines. The M was used to differentiate the engine from the previous 351 engines. The 351M is a sharp break form the other 351 engines because it is more similar to the Ford 400 engine. The last traditional 351 year was 1974; Ford decided to manufacture the 351M after that. It was used in the Ford F-150, 250, 350 and the Ford Bronco from 1977 to 1979. You can purchase a rebuilt Ford 351 on the aftermarket. Any installation or modification of the engine should be done by a professional.
Piston Firing Order
The pistons had a firing order of pistons 1, 5, 4, 2, 6, 3, 7, 8.
Ignition Timing
The ignition timing for the 351M engine was 8 degrees before top dead center (BTDC). To adjust the timing, the engine should be set at an idle speed of 800 rpm and all accessories should be turned off. The distributor vacuum hose should be disconnected and plugged. The emergency brake should be engaged with the transmission in neutral.
Camshaft Specs
The 351M had a deck height of 10.297 inches and compression height of 1.947 inches. The main journal measures 3.0 inches, the rod journal measures 2.311 inches and the rod has a length of 3.58 inches. The 351M had two-barrel cylinder heads. The combustion chamber was open and the port size was small. One set of cylinder heads had a combustion chamber volume size of 76.9 to 79.9 cc and another set had a combustion chamber volume size of 74.7 to 77.7 cc. The intake valve was 2.05 inches high and the exhaust valve was 1.65 inches high.
Camshaft Torque Specs
The main cap bolts had a torque of 105 foot-pounds and the valve cover had 10 foot-pounds of torque. The 0.3125-inch intake manifold bolts had 25 foot-pounds of torque, while the 0.375-inch bolts had 30 foot-pounds of torque.
Engine Dimensions
The 351M had a bore and stroke of 4.0 inches and 3.5 inches, and a compression ratio of 8.4-to-1. It had eight cylinders and a displacement of 351 cubic inches. The 351M is a 90-degree type engine with an overhead valve (OHV) configuration.
