driverchoice

how do the date codes work on heads i only see the three 3 # on the underside and then noticed the same 3# on the outside near the valve cover im guessing these are the day of the year but how do you know what year when c,d ,5 heads were used more than one year

2blu442

I don't think there is a way to tell which year heads were made when the code spans more than one year. I do know there are two different castings for C heads as I've seen both small and large heat crossover passages. Since earlier heads have small crossover passages I would guess the 1967 C heads have the small opening, but have seen no documentation to verify when the crossover passage became larger. John