History Question - 1956 TBird

Just purchased a fairly clean 56 TBird. It has a 292 in it, but the VIN plate says it should have 312. I asked the previous owner and he told me that the early 312's that the put in had some sort of problem and the dealer said that they could either wait for the problem to be fixed or swap in a 292. Has anyone heard of this, or has someone Swapped in a 292 somewhere along the line?


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I don't personally know, but if you sit and think objectively the story sounds totally ridiculous and fabricated. I can't imagine the dealer replacing an entire engine in a car with a completely different one in a new car, or the owner agreeing to it.
Actually, that's not true. All you need to do is look at the casting numbers on the block. Mine also has a tag on it that's says it is a remanufactured engine with the displacement, journal size, main bearing and bore diameter stamped on it.
Actually it is true. To determine the size of the engine, you need to look at the back of the crankshaft where the flywheel/flex plate attaches. This part will have a raised dot about the size of an aspirin on it if it is a 312. The casting numbers for the 312 and 292 the same in some years.
I work at the Preservation/Restoration center of the Crawford Auto Museum and I rebuilt a 292 engine from a 1955 Thunderbird. Since I had the crankshaft removed from the engine, here are photos of the crankshaft flange and the block casting number.

Since the block casting number starts with ECK, this is a 292 engine and not a 312.

Also, since 180 degrees from the semi circle cutout in the crankshaft flange there is something other than a raised circle on the recessed area, this indicates that engine is a 292 and not a 312.

I hope these pictures help you with your engine identification.

1955 Thunderbird Blue

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I think you misread my comment. I said that the casting numbers for the 292 and 312 were the same in "some" years. There was no 312 in 55. the 55 heads were unique in that they had a soft or freeze plug in the end if the head. This was eliminated in the passenger car engines in 1956 and later. The 312 was introduced in the 1956 model year and was used mostly in the Thunderbird but could be ordered in the Fairlane as well. The 1955 292 engines could have a casting of ECH, ECJ or ECL. Those casting numbers were not used on the 312 engine at all in any year. So you can identify those early blocks by those casting numbers. In 1956, EZK was used for some 292 engines. However, the problem starts with the casting numbers of ECZ-A, ECZ-B and ECZ-C, these engines casting numbers were used in 312 and 292 engines both in 1956 and 1957 model years. This is where you need to identify the crank OR the main bearing caps. If the engine with the ECZ- A, B or C has EBU main caps, it is a 292, if it has ECZ main caps, then the engine is a 312. I guess I should have listed all this information but I sand by the fact that the block casting number in "some" years (1956 and 1957) are not enough to identify the engine.

Even though the 312 was only used in Ford vehicles from 1956-1957, every Y block is listed as a 312 even though it could be one of the smaller engines. The block casting number is insufficient evidence of engine size in the 1956 and 1957 model years.
Attached is an article about T-Bird engine identification that was written by R. W. Dickson for the September-October 1997 issue of the Early Bird magazine, along with pages 26 thru 31 of the CTCI Restoration & Specification Manual. You should become a member of the Classic Thunderbird Club International, then you will receive the Early Bird magazine and be able to purchase the CTCI Restoration & Specification Manual.

1955 Thunderbird Blue