Ford 289 and 302 cubic-inch engines, both members of Ford's 90-degree engine family, are similar engines with many interchangeable components. Identifying the engine as a 90-degree small-block Ford V8 is the first part of the process; differentiating the 289 and 302 follows. These engines were manufactured during the same era, with the 302 eventually replacing the 289. The same block and cylinder heads were often used on both, however, differences in bore, stroke, and crankshafts exist. Known 289 and 302 casting number listings are available, and using them along with identifying the crankshaft will properly identify and differentiate both engines.
Identify the engine as a Ford 90-Degree small block V8. All Ford 90-degree engines have six bolts on each valve cover.
Locate the casting number. The block casting number is above the starter on the passenger side of the block. The casting number is the Ford part number for the engine block, "D4AE-6015-AA-10," for example. The most important part of the casting number is the four-position prefix. The remaining casting number sections are not necessary for identification.
Decode the casting number. According to Mustang Tek.com, the prefix D4AE decodes as an engine block manufactured in 1974 for a full-sized Ford. The decades are represented by the first position, "D" for the 1970s, "C" for the 1960s, etc. "4" is the decade year, "A" is the vehicle the engine was originally intended for- a full-sized model-"D" represents a Ford Falcon, "Z" is a Mustang. The last position, "E," stands for engine.. The block casting numbers do not identify engine displacement.
Reference the casting number to known listings. The casting number may be referenced to known 289 and 302 casting numbers for identification. These listings are incomplete, but offer an easy method to identify the engine. These listings are found at the Engine Factory website, What are You Working on?, the Mustang II Network and Kelly's Hotrod Page (see Resources).
Remove the oil pan to identify the crankshaft. The crankshaft is one of the few differences between 289 and 302 cubic-inch engines; the two are not interchangeable. The crankshaft identification code is normally located on the farthest forward counterweight and consists of two positions, "2M," for example. All 289 cubic-inch engines are marked with "1M" and 302 cubic-inch are marked with "2M."