Engine Identification Codes

Have you ever wondered what kind of engine you're looking at when opening the hood of a Ford? Well, Ford took some steps to make sure their service employees didn't have to guess when working on a car. The 428 CJ and SCJ, for example, were originally identified by a small steel tag that was mounted to the top of the engine under the ignition coil mounting bracket. The bolt that secured the coil bracket also secured the tag.

The tag included information to identify the engine displacement in cubic inches, the two-digit model year, the engine change level, the year and month of production, and an identifying engine plant code. The engine plant code on the tag should match the engine tag number found on the build sheet. The engine plant code contains three digits and an alphabetic suffix. One challenge to hobbyists has been in figuring out what the different suffixes mean. The 1975 MPC says that "prefixes and suffixes are for Ford Motor Company use only and do not affect engine identification". According to "The Mustang and Cougar Tagbook" by Kevin Marti:

"The suffix for the engine plant code is based on a three-year cycle. Leaving "I" and "O" out of the alphabetic code (to avoid confusion with the numbers 1 and 0), leaves 24 letters, which divided amongst the three years gives "A" through "H" for the first year of the cycle ('64, '67, '70, '73), "J" through "R" for the second year ('65, '68, '71), and "S" through "Z" for the third year ('66, '69, '72). These suffixes would be used internally for tracking of engine manufacturing changes. At the beginning of a model run, the first letter in the cycle (A, J, S) would be used. Sometimes the next letter (B, K, T) would be used later in the model run, and, in '64 and '73, the letter "C" is even seen. An example of this variation is when the Boss 429 motors for 1969 switched from 1/2" to 3/8" rod bolts, the tag changed from 820-S to 820-T.

Beginning in 1970, to resolve what had been a problem with cars that had engines that would require air conditioning compressors to be mounted to them at the engine assembly plant, the letter "G" was added after the suffix code. These engines would be identical to their non-air counterparts as shipped from the Engine and Foundry, but they would be set up for the air conditioning compressor."

1968 407J
1969 419T
1969 421T
1970 420A
1971 420B60
(Industrial Engine)

A summary of the documented 428 CJ and SCJ engine codes and suffixes appears in the following table.

Code Observed Suffixes Year Engine Type Transmission Type
407 J 1968 Cobra Jet Automatic
408 J 1968 Cobra Jet Manual
418 T 1969 Cobra Jet Manual
419 S, T 1969 Cobra Jet Automatic
420 A (1970), S, T (1969) 1969, 1970 Cobra Jet Manual
421 A, AG, B (1970), S, T (1969) 1969, 1970 Cobra Jet Automatic
422 T 1969 Super Cobra Jet Manual
423 S 1969 Super Cobra Jet Automatic
424 A (1970), S, T (1969) 1969, 1970 Super Cobra Jet Manual
425 A (1970), T (1969) 1969, 1970 Super Cobra Jet Automatic
426   1969, 1970 Super Cobra Jet Manual

Reproduction tags are available from Marti Auto Works. Please contact them directly for details.