The 390 in³, with 389.6 in³ or 6.4 L true displacement, had a bore of 4.05 in (103 mm) and stroke of 3.78 in (96 mm). It was the most common FE engine in later applications, used in many Ford cars as the standard engine as well as in many trucks. It was a popular high-performance engine; although not as powerful as the 427 and 428 models, it provided good performance, particularly in the lighter weight vehicles, and was in much greater supply. The 390cid 2v is rated at 265 bhp (198 kW) @ 4,100 rpm.
Ford combined attributes that had worked well in previous incarnations of the FE: a 3.98 in stroke and a 4.13 in bore, creating an easier-to-make engine with nearly the same displacement. The 428 engine used a cast nodular iron crankshaft and was externally balanced.
Standard 428 in³ FE engines were fitted to Galaxies (badged simply as ‘7 Litre’) and Thunderbirds in the 1966 and 1967 model years.
The following provides casting numbers for Ford engines applicable to classic Cougars.
Cylinder heads used on the W-code 427 through (about) mid-to-late Jan 1968 were casting # C8AE-6090-J and are supposedly the most difficult to find.
C8OE-6090-N cast heads were used after Ford ceased using the J heads.
Intake manifold casting is C7AE-9425-F. It is cast aluminum and also known as the Police Interceptor intake due to its use on thousands of Ford/Mercury 428 Police Interceptor engines.
— Source – Royce Peterson
The most prominent date for a production GT-E engine was July, 1967. There are some known originals from August and September of ’67. Certainly once you get into ’68 all the ones I’ve seen have been service replacements, rather than regular production.
— Source – Jim Pinkerton
All 427 side oilers made after about June 1967 were drilled for hydraulic lifters.
— Source Royce Peterson