Finally got around to looking into the casting numbers on the Y block in my Model A.  The block says "B9AE-6015-F" and the heads are ECZ-G, but I have no idea how to tell if they're big or little.  It's cast into that spot next to the driver's side intake coolant mating surface.  
One source doesn't even have those as options.  One suggested it may be a Mercury block.  
What do the experts say?

Your block was used in 1959 cars and trucks. It was also used in 1959 Mercurys. Fords were 292, Mercurys 312. If the main bearing caps are ECZ, it's a 312. 

ECZG heads were manufactured in 1957-58. Whether Big/Little, they have the same valve, port, and chamber size. If they were manufactured after May, 57, they should be "posted." "113" & "471" heads were manufactured in 1959, both of which are big-valve heads like the "G" heads, but have larger combustion chambers. You can find all of this information at ford-y-block.com. Thank you, John.

Thanks for the info.  I just checked out John's page.  Doesn't sound like there are any other EXTERNAL clues on this block to tell what it came from.  My Big M/Mercury Man valve covers feel a little more at home, knowing that at least the number matches up as being (possibly) a Mercury.  

As far as the block is concerned, there's no external difference, whether 292/312. 

You will first have to determine if your engine is a 292 or a 312.  As Jeff mentions, the outside of the block or casting numbers will not help you there.  If you spot the aspirin size dot on the outside edge of the flywheel flange of the crankshaft, then the engine at least has a 312 crankshaft.  Internally, if the block has EBU main caps, it’s a 292; ECZ main caps and you have a 312.

If a 312, then odds are very good your B9AE block is a Mercury block.  If a 292, then it’s a Ford car, pickup, or truck block.

Lorena, Texas (South of Waco)

Thanks, Ted.
Well, I'm planning a transmission swap for the winter so I'll look at and maybe get some photos of the flywheel flange on the crank.  Is this something that the flywheel would need to be removed to see?  
My money's on a 292- that's how it was sold to me and the previous owner.  If it was a 312, I would think that whoever put it in would have advertised that well knowing that it was more desirable.  

Whether it's a 292/312 makes no difference as far as transmissions are concerned. If you're thinking about installing a transmission that was not used with Y-blocks, the required adapter will fit either. Let us know which transmission you're considering, and one of us will tell you which adapter you'll need and where to get it. 

Here is a shot of the transmission that I will hopefully be picking up soon.  I currently am running a 3-speed toploader that I guess is referred to as a "3.03" in Ford circles.  Someone on the HAMB tipped me to the fact that for 1975-1976, AMC used a T150 with a Laycock de Normanville overdrive unit, and that he'd had over a decade of trouble free driving with one behind his Hemi.  As luck would have it, there was one I found on Car-Part.com in a junkyard in Pelham, NH- not too far from where my sister lived, so I called one day on my way back from her house and they still had it and the price was right...another "as luck would have it" came about when I found out that the "GO-TO, guru" for these things has a shop just under an hour from my house, so I dropped off with him back in February.  He emailed a week ago to tell me it was ready.  
Sounds like the only thing I'll need to change is to massage a fraction of an inch off of the tip of the input shaft and it "SHOULD" mate right up.  I'll just have to figure out mounting the back half of it, since it's WAY different...

I hope it all goes well. Let us know how it's progressing. 

You may have to turn down the front bearing retainer a little to fit in the Y bell hole.


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