351 Cleveland Cylinder Heads

D1ZZ-GA with sq port High port Plates

Photos and text by ebayer "no1musclecar"

One complete matched pair '71 Boss 351 High-Port modified heads, Ford factory part number D1ZZ-6049-B / D1ZX-6049-BA, Ford factory casting number D1AE-GA. Both date coded 0M15. Not to be confused with regular 1970 closed chamber 4V heads. These are the heads that make the ultimate race small block ford . Can be easily modified to run on a Boss 302 engine.

Modified in a batch of 55 heads, these are numbers 19 and 20. They were new heads bought from Ford in 1974 prior to being modified, likely by a race shop like Bob Glidden's or someone similar. I'm only aware of two or three companies that were doing this back then (the label says Jerry ______ Inc., in Indianapolis). They sat on the shelf for a little while, and look to have been shipped to Auto Mastics in Hawaii in 1976. Original Ford boxes will be included, one of which even has the abbreviation “CYL” misspelled as “CLY”. After very little use, the heads were shelved again. There was no catastrophic engine failure. No cracked heads. Just stored.

Fully ported and polished intake and exhaust ports, and all closed combustion chambers polished. Someone had once suggested these valves (2.23" intake/1.71" exhaust) were inconel (often used in industrial engines), but upon disassembly of one head, I found the valve to be too light and am certain the valves and spring retainers are titanium, like the valve train in my Boss 302 heads. As you'd expect, screw in studs for rocker arms, and factory guide plates are replaced with thicker Manley units. Don't know about the valve springs, but suspect anyone running these would replace them anyways.