The Stovebolt Site Forums The Shop Area The HiPo Shop Another non-typical engine problem

Jerry, I think you're right that the 38 zephyr is 14MM--that is the year Ford downsized the v8 from 18MM in the old 21 stud flatheads.The 32 v8 was the only year using the 7/8-18 thread plug like the A model.
The first year y-block (1954) was the only year to use 14MM in it.