Ford's 289-cubic-inch small block engine was one of Ford's most popular engines of the 1960s and was commonly used in the Mustang, Falcon, Fairlane and Cougar. Due to is relatively basic design, tuning the 289 is quite simple. However, there are a few commonly overlooked tuning tips that can significantly increase the performance of any 289.
Gapping the Spark Plugs
Failing to gap the spark plugs is one of the most commonly overlooked area of tuning. "Gapping" a spark plug refers to the process of ensuring that the distance between the metal electrode and the top of the porcelain tip at the end of the spark plug is correct. The measurement is taken with a feeler gauge, which, depending on the type of feeler gauge, consists of either a number of different blades of varying thicknesses or a number of metal wires of different thicknesses. The distance between the metal electrode and the top of the porcelain tip must be .034 of an inch for a standard production 289, and .030 for the high-performance 289. Insert the feeler gauge between the metal electrode and the porcelain tip, then gently bend the metal electrode until the proper distance is achieved.
Attention must be given to three components within the 289's distributor: the cap, the rotor and the ignition points. Within the distributor cap is a total of nine metal contact points. These contact points are responsible for directing the electrical current provided by the ignition coil to each of the eight spark plugs. Over time, each of these metal contacts develop a greenish-coloured corrosion, which can adversely affect the power of the spark. The rotor is located in the centre of the distributor. Its metal tip is also susceptible to corrosion. Therefore, both the distributor cap and rotor should be replaced as soon as any sign of corrosion is detected. The ignition points are located at the base of the distributor underneath the distributor cap and resemble a pair of tweezers. The points open and close as the rotor turns. Like the spark plugs, the distance between the points must be gapped. To gap the points, turn the rotor by hand and watch the points open. When the points are fully open, insert a feeler gauge between them. The distance between the points must be .017 of an inch for a standard production 289 and .020 of an inch for the high-performance 289. The points can be adjusted by loosening the single screw next to the points and either widening or reducing the gap.
Ignition timing refers to the point during the engine's rotation when the distributor sends a spark to each of the eight spark plugs. If the timing is not correct, power and fuel efficiency will be reduced. Checking the timing requires a timing light, which connects to the battery and the number one spark plug wire which, on the 289, is located on the passenger's side of the engine closest to the radiator. As the engine is running, the timing light is pointed at the timing marks stamped into the harmonic balancer. The timing of the 289 must be -14.4 degrees Cor the standard production model and -11.1 degrees Cor the high-performance engine.