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I'm trying to identify the engine that I've got in my 1955 F100 pickup. The previous owner told me that it is a 312ci form a 1957 T-Bird. I verified this from the engine code cast into the Y-block above the oil filter, which was "ECZ-6015-C". This does not completely identify the engine though, which I'm trying to figure out. What's throwing me is that it has a 2-barrel Holley 2100 carburetor in it, which does not seem to be standard for any of the 312's. It seems to run fine, so I expect the 2-barrel is fine for daily driving. I'm guessing the engine is the more common D-code and that somebody swapped carb's. I understand that there's a raised dot on crankshaft rear flange for D-code, but I haven't been able to find it yet. Is this something that would be visible without any teardown?
ECZ-6015-C blocks can can be a 312 or a 292. 292 were regularly shipped with 2 barrel carburetors. It is nearly impossible to ID a 312 externally. The generic advice is look at the main bearing caps or the rear crankshaft flange. The flange marking is not a guarantee though, and it is not visible when the engine is in the vehicle with an automatic transmission. With a manual transmission, it is possible the raised dot could be visible. The only surefire way is to look at the crankshaft bearing caps for the ECZ markings.
It is said every y block is a 312 until proven otherwise ;-)
I removed the flywheel cover and spun the crankshaft manually while looking at the rear crankshaft flange for the 5/16" raised dot which denotes the 312ci D-code engine from 57 T-Bird. I didn't see any dots at all for full revolution. But there was a single radial scallop cut, which is shown in attached picture. Anybody ever run into this and able to decipher which engine it is?
Meanwhile I suspect that the intake & exhaust manifolds, and carburetor, are from original truck V8 engine. This makes sense for intake manifold due to Holley 2100 2-barrel carburetor being present. And the exhaust has crossover pipe that the 57 312's do not.
I removed the flywheel cover and spun the crankshaft manually while looking at the rear crankshaft flange for the 5/16" raised dot which denotes the 312ci D-code engine from 57 T-Bird. I didn't see any dots at all for full revolution. But there was a single radial scallop cut, which is shown in attached picture. Anybody ever run into this and able to decipher which engine it is?
Meanwhile I suspect that the intake & exhaust manifolds, and carburetor, are from original truck V8 engine. This makes sense for intake manifold due to Holley 2100 2-barrel carburetor being present. And the exhaust has crossover pipe that the 57 312's do not.
I will say that I recently had a 292 here that I "thought" only had the crescent. It actually had a very faint recess that I could barely make out. Mine ended up being the 1 crescent and no dot "ec"
That was helpful. Where did you find that info? I just rotated the crankshaft a helf rev, and sure enough there was a keyway cut. With no dots, picture below.
The engine code casting "ECZ-6015-C" implies it's a 292 or 312. The crankshaft flange implies it's a 272 or 292. So together that means it's a 292. Does that sound right?
Then I assume the intake & exhaust manifolds are from maybe a 239 EBV engine, which was a popular engine in 55 F100. But this assumes that the bolt patterns match up. Anyone know if that is true?
That was helpful. Where did you find that info? I just rotated the crankshaft a helf rev, and sure enough there was a keyway cut. With no dots, picture below.
The engine code casting "ECZ-6015-C" implies it's a 292 or 312. The crankshaft flange implies it's a 272 or 292. So together that means it's a 292. Does that sound right?
Then I assume the intake & exhaust manifolds are from maybe a 239 EBV engine, which was a popular engine in 55 F100. But this assumes that the bolt patterns match up. Anyone know if that is true?
yes all you said sounds correct
http://www.ford-y-block.com/index.html
Last edited by bigwin56f100; Mar 1, 2026 at 02:59 PM.
Is there a way to decode VIN number of 55 F100, so that I can identify which engine was originally installed? I don't see this in the shop manual. Maybe there's other interesting things the decoding could show as well. My VIN is F10VSE17298.
I had no idea where the Edgewater Assembly plant was . So I looked it up. From Wikipedia.
"The Ford Motor Company Edgewater Assembly Plant was located in Edgewater, Bergen County, New Jersey, United States. The factory began operations in 1930 and was closed in 1955, having been replaced by the Mahwah Assembly plant. The building was built in 1929 and added to the National Register of Historic Places on September 15, 1983, located at 309 River Road. The building was torn down in 2006 and replaced with a residential development."
I had no idea. And your truck was built in the last year of its use.
Abe, I had a 3/4 ton 1954 Fxxx back in 1988, from a barn find in PA. Now I got a 1/2 ton 1955 F100 with unknown history from RI. I got one picture of each, both with bandage on my right hand. Hand was broken from fight for the 1954. Hand is recovering from trigger finger surgery for the 1955. When I see your avatar picture, it brings back memories.
It was Blue Bell PA which is between Philly and Allentown. Both rear wheels were rusted frozen. We dragged it around farm with tractor to free up the wheels. I rewired it 12V neg gnd and did minor upkeep, but never spruced it up. It was my solo vehicle and was pretty reliable. I had it about 5 years and then bought new Ford Ranger, cause my girlfriend complained about riding in the 54. Didn't have place to store the 54 so had to sell it.
