There are no casting numbers on my heads as the numerous websites have shown. I've only found "73B", a "G" and a "15". The valves are the larger 1.92" size. Are these the ECZ-G heads?

 

The numbers will be on the heads somewhere. Make sure it is clean, use a light, and magnifying glass, if necessary.

I'm pretty sure that is a G head.

 

I guess its time to pull out the 'ole drill and wire brush.

 

It looks like a G head. The casting numbers are usually on the intake port side of the head at one end..

 

I found the casting number! It's ECZ-G. Aren't these fairly desirable heads? I like the fact that they have the bigger valves. Now I wish I knew if these were '57 or '58...

 

They are among the best factory heads for the Y.

I'm rusty on date codes, but I think the 73 and backwards B is the date code, so 1957 (7) March (3) 26 (backwards B). The letter corresponds to the day of the month, excluding I and O for confusion, that's 24 days and the backwards letter indicates that the count started over, so 24 + 2 (B) is 26.

The date doesn't matter much, unless you are trying to build a vehicle to be as correct as possible and these are not correct if they are for a 56 F100.

 

Nice! No, not trying to be correct, just trying to find the most accurate specs for this engine. Thanks for explaining the 73 B.

My dad and grandpa actually swapped this engine in to replace the 272 back in '69 or '70.

 

are those heads off a thunder bird 292

 

all 57 engines used g heads.theres no such thing as tbird heads.they used the same heads as ford.