428 Block with 20F Stamp

[breedb]

I have a 428 Block that has a 20F Stamp. Does anyone know how to cypher that code? I was told it's a code for the assembly date of the car. If so, what is the date?

[Mark IV]

..20 (date, the 20th day of the month June (A=Jan, B=Feb, etc. so "F" is June. Should also be a year of casting identifier on the block.

Rick

[Woodz428]

Casting date on an FE block is usually under the oil filter pad visible from the bottom and it is cast into the block. The stamped # is assembly date of the engine and is usually on one of the machined bosses (probably the left front one below the exhaust port area). The date is year, month and day, like 6A17 (Jan.17,1966) same for the casting #'s so the 20F is probably another # (since there was no 20 year)

[breedb]

I looked at the oil filter housing boss and there are 2 sets of numbers. The first says "E1" and below that it says "8F4." What does the E1 stand for?