How do you tell what size of engine is in a 1976 ford F100?

Answer 1

if its a in line 6 its a 300ci------ if its a v-8 3to 4 options 302small block 351w still a smill block 351 Cleavland big block 400m or 460ci......

http://www.fordf150.net/howto/decodevin2.php

Use the VIN Decoder to find your motor if you know it is either the original or was replaced with the same size. The 4th character is your Engine Type.

As to the previous answer, correct me if I am wrong but from 1973 to 1976 the "H" code was for their 390cid.