The "good" 351W heads (69-74's) have "L" shaped coolant ports on the intake face, along with two extra bolt holes, in the "L" (two per head) That's the easiest quickest way to tell em apart from 302 and the later 351W heads.
Casting numbers. The letter at the beginning is the decade, followed by a digit which is the year in that decade. C = 60s, D = 70s, E = 80s, and so on... C9 heads are 1969... D0 heads are 1970... D1 heads are 1971... Now, they didn't always make a new casting each year, so a 1970 casting would still be a D0, even in 74 if they hadn't changed anything in the casting design. So you can find earlier dated parts on a later car, but never later parts on an earlier model car. (Unless changed later in life) 351w heads have the digits '351' cast into them somewhere. Either under the valve cover or on the bottom of the intake runners. D0OE is the most common casting number for the early W heads. C9OE heads could be marked "2v" or "4v", and the 4v heads bring big money. Most folks think they are better... The only difference between 69 4v heads and 69-74 2v heads is 2cc smaller combustion chamber. Nothing else. There were 70 model 4v heads for marine use and warranty service on C9 heads, but I am not famliar with the numbers for that one.
Im actually the heads that im trying to use are 302 heads but have been drilled out to use the bigger bolts for the 351 and im trying to install them on a 302. I called a few machine shops and they said that the spacers or the larger bolts wasnt really necessary. But i dont know. The heads im trying to install have had just the exhaust side ported and you could tell the differece big time. The heads im using are the 86 302 ho heads i think they have the heart shaped chambers that shroud the valves.
In this case, you're taking a step backwards in power production. You're talking about E6SE heads which in stock form are 25 HP short of what stock E7TE heads make.
Never seen an E6TE head. If they've got the heart shaped chambers, they're E6SE's. They will have an "S" cast into one corner, next to the valve cover rail. E7TE's have a "T" in this location.
They're good for emissions purposes, and nothing else. And although they look smaller than E7 chambers, they're not.(68 cc E6 vs 64 cc E7) They're deeper than all other small block Ford chambers, the valves are a full 1/4" deeper into the head, this is the reason Ford went with true flat topped pistons with no reliefs in the engines they were used on. (86 HO 5.0 & 86-91 Crown Vic, Towncar, Marquis 5.0, plus some of the T-Bird/Cougar 5.0's) The valves are so far away, there was no chance of them ever getting close enough to the pistons to need reliefs.
E6ae-aa is the correct number off those im sorry. Im gonna still use them as they are already ported and have a fresh valve job. i wish i would have know this before i did the work.Lol This will for sure be my last ford to build.
