I am a new owner to cougars so any help would be appreciated, I have a 73 vert and the VIN says “H” for the engine so I assumed was a cleveland (car is mostly original) but when I bought spark plugs I realized the old plugs were not coming off with a 5/8 puller so after looking at the engine I think I have a Windsor. It has 6 valve cover bolts (clue 1) and the thermostat is mounted to the intake (clue 2) vs the water pump housing so a I on the right track here ? The other question is the build date on the vin sticker says 9/1972 and is production number 3,052 so is it common that they kept the windsor in early production because they also used “H” code in 72 to id the windsor as well as “H” code on my vin for cleveland
For all 1970-1973 Cougars the H engine code could be for either a 351W or a 351C. There is no way to tell which engine a car left the factory with just by the H code. I am not sure if a Marti report would spell out which engine version a car originally had. One thing you can do would be to look for the original factory VIN stamping on your engine. Your description of the thermostat housing sounds like a 351W. Another way you can look at is if the thermostat housing points toward the radiator it would be 289/302/351W. If it points straight up toward the hood it would be a 351C. 289/302/351W valve covers have rounded upper corners, 351C covers are square. Timing chain covers are different too.
I have never seen a 351W engine in a 1971-73 Cougar.
Kevin Marti doesn’t even list a 351W engine tag, in his tag book for 1972-73 cars. Yes, they are listed in 1971, but that means they may have been installed in a Mustang at some point in time, at one of the various factories.
Interesting - so it sounds like 351C and W were used interchangeably for 71-73, but W was rarely if ever used in Cougars? Guess I thought Ford ended the Cleveland in 74. Ford sure didn’t get much opportunity to pay off their huge investment in the Cleveland engine.
I have parted out a couple of the 71-3s with a W in them. I will not say that they were the original engine. It was too long ago for me to remember all the details plus back in the day I did not concern myself with verifing originality.