Thread: still my 390

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hi guys. i am still trying to find what my motor is. i read all your forums and it is helpful. the only numbers i can come up with are. left side of block 20 under oil filter only 20 can be read. right side of block c6me-a . any help is appreciated thanks bob

Is this a running engine in a car/truck? G.

Just saw your other post and see it's in the stang. The 20 you see under the oil filter is part of the date code. There should be more and you might have to wire brush the area a little to see it all clearly. Your looking for a number/letter/number(s) sequence. Also the heads have a casting number and date code. The heads casting number is between the center two spark plugs and the date code above it under the valve cover. Almost everything on the engine will have some sort date code or casting/part number. Now I'm not sure if you can find out the build date of your car or not but without it you can only estimate by the date codes if they are correct. With the build date you can determine if they are original to the car. Kevin Marti would be the one to contact. I know 68 and later info is there but not sure on 67. Perhaps someone else can clue you in on that also. G.

Hi. The C6ME-A block is listed as a 390 or 428, but I'm sure there are other things it was used for - it's sort of a generic block casting number from what I can tell. With the engine in the car, there isn't much you can find out for certain. If you have the engine out, on the back of the block, a rough "A" scratched in the sand before the block was cast will mean a standard 428 (big cars, police cars). A "C" in one that was cast after about the end of '67 (7Mnn date code or so), will be a CobraJet block. An early one, the "C" supposedly indicates a 390, but that was on early castings. Just the 352 indicates it's a 390.

The pan is usually easier to remove than the trans. If the crank has a "1U" stamped on the side of the counterweight (I think it's the second from the back), it's a 428 crank, which was also used in the Merc 410.

Like FFR428 said, the 20 is part of the date code. Format is nlnn, where the n's are numbers and the l is a letter. The first number is the year of the decade, assumed to be the 1960s. The letter is the month of the year:

A - January
B - February
C - March
D - April
E - May
F - June
G - July
H - August
J - September
K - October
L - November
M - December

The last two digits are the day of the month. The heads I've got are 7M14, meaning they were cast on December 14, 1967. They're the 12-bolt C8AE-H heads (these are the ones on the pickup engine - the Shelby is C8OE-N), so I know they were for a 390GT. Mustang, Fairlane, whatever? Hard to say.

Anyway, it's not easy telling what you've got, unless you take it apart. The engine I've got for my pickup came out of a '68 Mustang, but we didn't know much more than that until disassembling it. The bore is 4.110, so it can't be a 428. They're 4.130. The 390 is 4.050, so we really could only have a 390 that was bored .060 over.

Check the date on the block. If it's original to the car, and the date seems right, then look at the engine code on the serial number. The 390GT cars had a "S" in the fifth position - something like "8F02S216510" for a '68 Fastback, assembled in Dearborn, with a 390GT.

As an aside, on the '69 and '70 Shelbys, the serial number will always have 48 as the first two digits of the sequence number, and will always be assembled in Dearborn. If they haven't been mashed up too badly, they will have the matching VIN stamped on the front fender aprons, just like all the other Mustangs. If your car has the VIN forward of the shock towers on the aprons (both sides), it probably hasn't been hit hard enough in the front to require the aprons be replaced.

Don't know if any of this helps, but good luck.

Oh, one more thing. The intake for the 390GT has a big "S" cast in one of the runners at the front of the engine, near the casting number.