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HOW TO IDENTIFY A 312
IT IS NEARLY IMPOSSIBLE TO ABSOLUTELY IDENTIFY A 312 EXTERNALLY!
312's were installed in all 1956 Mercurys, some 1956 Thunderbirds and Ford Cars. Many 1957 Thunderbirds had 312's and all 1957 Mercurys had 312's unless equipped with the 368 Turnpike Cruiser engine. Some 1957 Fords had the 312, typically station wagons, Fairlane 500's ect. All 1956 and '57 312's had a 4 barrel carb. From 1958 to 1960 312's were only installed in Mercurys. No 312's were installed in trucks at the factory!!!!!
BLOCK CASTING NUMBER:
312's can have the following block casting numbers ECZ-6015A, ECZ-6015B, ECZ-6015C,
EDB-6015E, B9AE-6015F. Of these ECZ-6015A and ECZ-6015C are by far the most common 312's and are likely to be a 312. Some 312 replacement blocks were C2AE-6015C. Any of these numbers can also be a 292. The following blocks have never been seen as a 312: EBU, EBY, EBV, ECG, ECK, ECL.
312 crankshafts typically have an identifying mark on the crankshaft flange. This cannot be seen if the engine is installed in the vehicle with an automatic transmission. On a manual transmission vehicle the mark might be seen between the block and flywheel. If the engine is out of the vehicle and the bellhousing is removed the mark can be seen. Many 312 cranks are stamped ECZ, but not all are.
Outer edge of flange DOT ON FLANGE
Not all 312 cranks have this aspirin size raised dot!
CRANKSHAFT MAIN BEARING CAPS:
312 main caps are always marked ECZ , all other Y-Block main cap are marked EBU. This is the only positive way to identify a 312 block.