My block C8BA has what I determine to be Merc heads (8CM)

Does anyone know if Ford and Merc heads were the same and interchangable, or could it be a 255 engine?

There is also a tag that states the engine was rebuilt by "Precision Machining in Toronto an authorized Ford rebuilder." This may account for the fact that it is a '48 block in a '53 F100.

Thanks
Chris

 

Chris,
Ford and Merc heads are interchangeable, but are not the same. Different years have different compression ratios - depends on the depth of the cutout over the piston and valves.
If you're asking if they could put Merc heads on a Ford, the answer is yes, but with an 8CM block I'd say the odds are in your favor that its is actually a merc.
The only way to verify this is to pull a head and measure the stroke from top of the block to the bottom of the piston travel. If 4" then you have a merc crank, but 3 3/4" and its a Ford crank.