1967 Ford 300 Tuneup Specsby Marlin Quintana
The Ford 300 is a 300-cubic-inch (4.9-liter) inline six-cylinder engine that was first unveiled in 1965 and put to use mainly in light-duty trucks. Bore diameter is 4.00 inches and stroke length is 3.98 inches, making the engine slightly oversquare. The 1967 engine used a one-barrel carburetor and an 8.0-to-1 compression ratio to produce 170 horsepower.
Spark Plugs and Pressures
The Ford 300 uses Autolite BTF-42 spark plugs, with a gap of .032 to .036 inch. Plugs should be tightened with 15 to 20 foot-pounds of torque. Fuel pump pressure should be 4 to 6 lbs. at 500 rpm, with volume of 1 pt. in 30 seconds. Cylinder compression should measure 150 to 200 lbs. at sea level.
The firing order of cylinders is 1-5-3-6-2-4. The distributor point gap should be .024 to .026 inch, while dwell angle should be 37 to 42 degrees. Some 300s include an air injection reaction (AIR) system for reduced emissions. For these engines, ignition timing should be set to top dead center (TDC). Without AIR, ignition timing should be 6 degrees before top dead center (BTDC) with a manual transmission, and 10 degrees with an automatic. Ignition timing should be measured with the engine running below 550 rpm.
Idle speed should be adjusted to 500 rpm for engines with AIR. For non-AIR engines, idle speed should be set to 600 rpm for manual transmissions, and 525 rpm for automatics (with air conditioning on). Valves are arranged as follows (where "E" represents exhaust and "I" represents intake), from front to back: E-I-E-I-E-I-E-I-E-I-E-I. Valve tappet clearance should be .082 to .152 inch.