1968 Ford 300 Engine Specsby John Stevens J.D.
The 1968 Ford 300 was a six-cylinder engine equipped with a single-barrel carburetor. The engine was first produced in 1965 and was largely based on the slightly smaller 240 engine. The engine is considered by some to be one of Ford’s most reliable six-cylinders of the era and was known more for its torque than its horsepower. Due to the engine’s simple design, rebuilding the 300 is fairly straightforward, provided that the engine’s specifications are followed closely.
The 300 featured a stroke of 3.98 inches and a bore of 4 inches. The compression ratio was 9:2. The 300 produced 170 horsepower at 3,800 revolutions per minute and 283 ft.-lbs. of torque at 1,600 RPM. Normal oil pressure is between 35 and 60 pounds, depending on the speed of the engine.
The 300 was equipped with Autolite brand BF-32 spark plugs. Spark plug gap is .034 inches. The distributor point gap is .027 inches. The distributor’s dwell angle is between 35 to 40 degrees. Ignition timing is 6 degrees before top-dead-center. Hot idle speed is 600 revolutions per minute with the headlights and the air conditioning turned on if the engine is mounted to a manual transmission. Hot idle speed is 500 RPM with the headlights turned on and the air conditioning turned off if the engine is mounted to an automatic transmission. Cylinder compression must be between 155 and 195 pounds. Fuel pump pressure is between 4 and 6 pounds.
Valve spring pressure for the 300 is 80 pounds at 1.66 inches. Stem clearance for both the intake and exhaust valves is between .001 and .0027 inches. Stem diameter for both the intake and exhaust valves is between .3416 and .3423 inches. The valve seat angle is 45 degrees, and the valve face angle is 44 degrees. Valve spring installed height is 1-1/16 inches.
Pistons, Pins, Rings, Crankshaft and Bearings
The 300’s piston clearance is between .0014 and .0022 inches. Compression ring end gap is .010 inches. Oil ring end gap is .015 inches. Wrist pin diameter is .9121 inches. The rod bearing shaft diameter is between 2.1228 and 2.1236 inches. Rod bearing clearance is between .0008 and .0015 inches. Main bearing shaft diameter is between 2.3982 and 2.3990 inches. Main bearing clearance is between .005 and .0015 inches. Crankshaft endplay is between .004 and .008 inches.
Cooling System Specifications
If the 300 was equipped without a heater, the engine holds 12 quarts of antifreeze. If the engine was equipped with a heater, the engine stores 13 quarts. If the engine is equipped with or without air conditioning, the radiator cap relief pressure is between 12 and 15 pounds. The thermostat opens at a temperature of 195 degrees.
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