Ok, so here's the information I have been given , for either a 312, or 292 the block numbers are ECZ-6015A or ECZ-6015C. I think I have the one with the C. Now here's what I have been told that indicates a 312, on the crank flang there will either be a indentation with nothing, 292, or a indentation with a bump or something of the sort, 312, right? I am going to try and post a photo that has the indicator, and let me know if I am right.

Its a 312 

Cant really go by any of the block numbers-only the crank.

Oldmics

Yep!

   God Bless.   Tim                           http://yblockguy.com/

350ci Y-Block FED "Elwood", 301ci Y-Block Unibody LSR "Jake", 312ci Y-Block '58 F-100, 338ci Y-Block powered Model A Tudor

tim@yblockguy.com  Visalia, California    Just west of the Sequoias

Yeah I know the block number don't really mean anything, they just give a 50/50 chance. However I was curious to know if what I pictured in the attachment was correct for a 312. I know it is kind of hard to see, but it was dark, and in a close tight area as the engine is sitting on the ground inside, and I had to use a mirror to see it. Is it a correct mark for a 312?

Hi,  If you go to John Mummert's site, it will show you the proper marking for a 312 crank.  I can't tell from your picture, sorry.  His site is http://ford-y-block.com and there is lots of useful information there.  Good luck, Nick Brann - K.C., MO

You are looking for a 5/16” dot on the outer edge of the rear crankshaft flange to positively identify the cranshaft as one from a 312.  That dot  is just about the width of the rear crankshaft flange.  A dot that is ¼” or less in size or multiple dots will indicate a 3.3” stroke or 292 crankshaft.  No dot being present can point you to either a 292 or a 312.  Getting back to the blocks, ECZ on the main caps is a resonably good indicator of a 312 engine.

If the crankshaft is at a point where you can see the #1 throw, then look at the lightening hole in that journal.  A 15/16” diameter hole will be a 292 crankshaft while a ¾” hole will be a 312.

Here are some past threads on identifying 312 crankshafts but for the most part reitterates what I just mentioned.

http://forums.y-blocksforever.com/Topic14196.aspx

http://forums.y-blocksforever.com/Topic19085.aspx

Lorena, Texas (South of Waco)

Ted, you raised the point i was going to make re the dot system, yes the 312 does have a 5/16" flat dot but not to confuse it with Smaller raised dot, I,ve even had cranks with 2 raised dots, one slightly smaller than the other and have allways wondered their application.  Your info now clears this up.  Thank you. regards bill.

  AussieBill            YYYY    Forever Y Block     YYYY

 Down Under, Australia

Okay, so I came up with a different idea, since I didn't feel like pulling apart my engine to see which is which, obviously I could take a 292 that I know is a 292 and bring one cylinder to the bottom of it's stoke and measure it. My suspect 312 I did the same thing and when you measure through the spark plug hole, the suspect 312 came up an 1/8 to a 1/4 inch deeper than the 292. The stroke of a 292 is 3.30, and the 312 is 3.44, so wouldn't the deeper measurement indicate 312?

I think you have a 312. Doing some basic trig, the 312 when measured through the spark plug hole should be about .131" deeper. That's just over 1/8" (.125")


Lawrenceville, GA

That's what I did, and that's about what I came up with, other than I can not compensate for an over bore if there is one, but with the information that I have I am fairly sure this is a 312.