I have a 1956 Mercury Montclair with a 312 and automatic transmission.  I know the car originally came with a 312, but I'm trying to figure out if the engine that is currently in the car is the "original" engine that came with the car or if has been replaced at some point throughout the years.  Can anyone point me in the right direction as to where to look and what numbers I need to compare?  Thanks a bunch.

Welcome Piper,


South Australia

For the cost of an oil change and the rental of - if you don't have one - a "borescope" you can look in through the oil plug drain hole and look at the main caps.

"If the engine is disassembled, check the casting number on the main cap. ECZ is cast into 312 main caps; all others are EBU."
From an article by John Mummert mentioned by Slick56
Identifying Ford Y-Block Parts (Part 1)
June 4, 2009
http://www.precisionenginetech.com/tech-explained/2009/06/04/identifying-ford-y-block-parts-part-1/

Jim
Norfolk, VA

"MABLE"
1956 Thunderbird Green / Brown Interior (ZE-XG)

"MEAN GREEN"
1956 Mainline (FG-BE)

There is no way to determine if the engine you have is the original engine unless you know the full history if it..  The only clue that it might be is the manufacturing date, which should be sometime before the manufacturing date of the car.  The coded manufacturing date is cast into the block.


54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

Presuming your vehicle is a U.S. model, as stated, there is no way to be sure externally, except if you remove the transmission, where you may find a 5/16" wide, shallow dot on the crank flange. However, some 312 cranks apparently didn't have that dot. Link & refer to J. Mummert's specs for further information on crank flange markings.      


Paul

I too, am in a situation on how to determine if a y-block is a 312, someone told me the dot on the crankshaft is on the OD of the flange, and can be seen without removing the transmission. Is this true?

Yes, more info herehttp://www.ford-y-block.com/identify312.htm




South Australia

If the crankshaft has the identifying raised dot on the rear crankshaft flange, then it can be seen without pulling the transmission.  The front flywheel cover will need to be removed though.

Here are links to past threads with more detail.

http://forums.y-blocksforever.com/FindPost8676.aspx

http://forums.y-blocksforever.com/FindPost14214.aspx

http://forums.y-blocksforever.com/FindPost47767.aspx

http://forums.y-blocksforever.com/FindPost80058.aspx

Lorena, Texas (South of Waco)