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By carl - 17 Years Ago
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i looked at a 57 merc. engine today that was supposed to be a 312 but it didnt have the raised bump on the rear of the crankshaft like the other 312 engines i have. the question is did all 312 have this raised bump or was some without it. carl
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By Tom Compton - 17 Years Ago
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More than likely, the original 312 was replaced soem years back with a 292. TC
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By marvh - 17 Years Ago
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Not all 312's have the rivet on the crankshaft flange. I have 57 Merc 312 engine without it. 312 Cranks without the rivet are very rare. The best way to be certain it is a 312 is to pull the pan and check the rods or crankshaft. The crank will have ECZ stamped on it, original rods will have ECZ also. If it is a Canadian engine it will have two letters followed by a number stamping on the front of the block drivers side just below the head/engine deck such as TV ####, 1956 blocks or VV####, 1957 blocks
marv
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By 46yblock - 17 Years Ago
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I have a 312 crank. You need to look VERY closely at its flange to see the bump, but it is there, barely. When I first saw the crank the bump wasnt visible, but the mains measured proper. It is now newly turned to 292 mains.
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By PF Arcand - 17 Years Ago
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Carl, just to clarify the 312 bump as you called it, is found in the notched area of the crank flange & is fairly short, but is about 5/16" in diameter.
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By carl - 17 Years Ago
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Thanks for the info. i know how to check the engine on the inside but wasnt sure about all 312 haveing the bump on the crank.i suppose i will have to buy it just to pull it apart and see if it is really a 57 312 carl
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By Ted - 17 Years Ago
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With the engine installed in the vehicle, the aforementioned 5/16” dot or bump on the crankshaft is most easily seen from the bottom of the vehicle when the TDC on the damper is at the six o’clock position. The 5/16” dot will then be at about the 5:30 position on the lower edge of the crankshaft flywheel flange when viewing from the front. Any covers or shields that block the view of the crankshaft flange will of course need to be removed to see this crankshaft flange. Ditto on some of the 312 cranks not having the 5/16" dot as I've had one of those also.
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By carl - 17 Years Ago
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the engine is out of the car with the bellhousing and flywheel off so it is easy to check the end of the crank.we pulled a head off yesterday and it has the standard 312 bore.next we will put it on a engine stand and drop the pan and check the main caps. carl
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By suede57ford - 17 Years Ago
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I recently bought a 312 crank with no dot or flat on the flange. I measured the mains and compared to another 312 crank and it checks out. First one I had seen too. I thought I got took until I measured it.
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By Larry D - 17 Years Ago
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I'm just pulling a 312 apart that has no dot on the crankshaft. It's a Canadian 312 engine from a '57 Merc and has the VV suffix stamped on the left side of the block below the cyl. head. It's a 3.80 bore with ECZ main caps. This is the second '57 Merc engine I've seen that doesn't have the dot on the crank. Maybe it's a '57 Merc thing? I'll be posting photos of the teardown later this month on www.fabulous50sford.com Larry D Fabulous 50's Ford Club of MB '57 Fairlane 2 dr. HT. - '58 Custom 300 Tudor - '61 Starliner Z code - '56 Crown Victoria Skyliner (clone)
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By Ted - 17 Years Ago
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Larry D (12/6/2007)
Maybe it's a '57 Merc thing? Larry DI looked at a ’57 Merc 312 I have on hand and it does have a very pronounced 5/16” dot on the crankshaft flange so it’s not a ’57 Merc thing specifically but maybe a Canadian thing?. Good thought though.
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By Larry D - 17 Years Ago
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I got out to check on my Y-Block stash and found my other '57 Merc 312 crank I've been saving for a good many years. There at the cutout on the crank flange was the 5/16 dot. That was also a Canadian car, so it looks like it's neither a '57 Merc or a Canadian thing. Moral of the story is, just don't write off any engine as not a 312 until you pull the pan and look at the main caps.
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By carl - 17 Years Ago
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We took the oil pan off the 57 merc engine and it is a 312. so like some of you said all 312s dont have the DOT on the crankshaft Carl
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By PF Arcand - 17 Years Ago
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Just a reminder to anyone buying a 312 engine. Once it's determined that it is in fact a 312, your next step before you spend any money on it, is to determine that the block is not cracked where the main caps bolt on. Or in some cases the threads may be stripped due to overtightening or as a result of the wrong length bolts ( to long or to short) having been used. Some early 1956 engines were victims of a main bolt torque spec that was to high. ( I won't repeat it here, or sure as hell someone will use it!) Also, when rebuilt by over zealous mechanics, the same happened. As I undertand it,(I'm not an engine guru) the "absolute" max torgue on 312 mains is 105 lbs! The Street Rodder/ Classic Truck series recommended 90lbs..
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By Larry D - 16 Years Ago
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Well we finally got our Y-Block torn down and even though the crank flange didn't bear the usual 5/16 dot, it's a 312. This looks like a good engine for a rebuild. Check out the photos at http://www.fabulous50sford.com/mr/mr-5.html
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