Re: xf cyl heads
Hey, if found this info from fordsix.com so i didnt write it, but here it is ne way.
XD Alloy head. One type used between all flavours of motor. August 1980 - March '82
Early XE head. Identical to XD head. Both had HF-1 cast in raised lettering into the rocker gallery. I'd say its safe to assume they're the same. March '82 ~ December '82
Mid-XE head. Identical intake and exhaust passages. Had an EFI notch cast into the head. Unsure on casting number. December '82 - Early '84
XE EFI head. Porting as above, except the combustion chambers appear larger. Unsure on size though. Enough to catch ones eye. December '82 - Early '84.
XF Carb/EFI head. Heart shaped combustion chambers. EFI notching cast into intake ports. HF-9 cast into rocker gallery. Early '84 - Janurary '88
Late (post ULP) XF EFI head. As per standard XF head, but fitted with larger intake valves (1.83" IIRC). To those who dispute this, there is a separate Ford part number for the larger valves. I believe this late change was instituted to compete with the VL Skyline's RB30E / RB30ET motor, and the upcoming VN commodore. Early '87 to Janurary '88.
Some general notes;
Standard intake valves are 1.75". As has been mentioned before, these heads Will accept Cleveland roller rockers, and 4V Cleveland valve Springs. XD and early XE heads are old; they may need a fair amount of TLC, especially if tap water has been used in place of coolant (it tends to rot the alloy to the point of coolant seeping onto the block!). I believe these heads to have been phased out around December 1982, or the advent of the EFI XE. With the exception of EFI heads, Compression Ratios were varied by different piston dish capacities. In my opinion it is safe to run unleaded fuels on heads designed with leaded petrol in mind. Alloy Heads have renewable valve seats, even if Valve Seat Recession were to occur, it would happen over many hundreds of thousands of km. Stem Seals would perish before the seats IMO. As an aside note, Crossflow motors were used up until the XG series was instituted in March 1993.
It is (also) my opinion that the XF head in any flavour is the pick of the bunch. While in stock form, the charge agitator cast into the combustion chamber provides some restriction, but with some creative grinding, it'll make for a better head than previous incarnations. Ford originally put this in to provide a means to lean out the engine a bit, to improve economy. As a side-effect, mid-range torque also improved. A full port job is preferable, but is only really needed on the exhaust side, to remove the thermactor bumps, perhaps also to clean up the pockets too. If you're really keen for flow, only a small amount is required on the intake side. Remember, the porting on these heads was done by Honda, with only a few design tweaks instituted by Ford along the years. It is considered state-of-the-art for OHV engines, even today.