[rose62]

I have a potential buyer for my engine. It has a casting date of "5H25." Could this be an original engine for a '66?

 

[carlite65]

I have a potential buyer for my engine. It has a casting date of "5H25." Could this be an original engine for a '66?

is that a stamped assembly date or a cast in block date??

 

[awhtx]

5H25 is August 25, 1965. So if the block was cast on August 25 and it takes 2 weeks to a month before it becomes a complete engine then it would be correct for a car assembled in the Sep/Oct time frame. Ford was cranking out Mustangs as fast as they could assemble them during this time period so I would say that the casting date and assembly date would be within no more than 2 months of each other. Your block would be correct for an early '66 Mustang.

 

[rose62]

Block casting date. Is there a stamped-in assembly date on all blocks?

 

[awhtx]

Yes, just forward of the driver side head. If the deck of the block has ever been machined it may be gone.

 

[rose62]

Assembly date is 5H26T. Data plate says build date of Sept. 9.

 

[awhtx]

Assembly date is 5H26T. Data plate says build date of Sept. 9.

I don't see how the block could have been cast one day, all the machining done, and then assembled into a complete engine the next day. But when you're cranking them out as fast as possible I guess anything can happen.

 

[rose62]

I don't see how the block could have been cast one day, all the machining done, and then assembled into a complete engine the next day. But when you're cranking them out as fast as possible I guess anything can happen.

Yeah, seems unlikely. But, doubtful that the engine was replaced with another built within such a tight timeframe, yes?