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By flathead_jr - 14 Years Ago
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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.
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By Oldmics - 14 Years Ago
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Its a 312  Cant really go by any of the block numbers-only the crank. Oldmics
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By mctim64 - 14 Years Ago
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Oldmics (7/31/2010)
Its a 312 Cant really go by any of the block numbers-only the crank. Oldmics Yep! 
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By flathead_jr - 14 Years Ago
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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?
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By Nick Brann - 14 Years Ago
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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
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By Ted - 14 Years Ago
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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
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By aussiebill - 14 Years Ago
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Ted (8/2/2010)
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. 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. 
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By flathead_jr - 14 Years Ago
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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?
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By charliemccraney - 14 Years Ago
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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")
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By flathead_jr - 14 Years Ago
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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.
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