Thread: identifing 390 block early model?ribs

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Originally Posted by robert55

well the engine mounts are two bolts, he said it came out of a 72 f250 i mean regardless if it came out of a truck or not i just want it to be a 390 lol if it is. i will check the bore size tonight. the only numbers i could find on the crank were bb and on the rods c4ae no following letters. and measuring the borehow am i going to know which size it is? i mean the tape isnt going to be accurate, how am i going to tell the difference between 4" to 4.050"?do uguys know what the ribbing stands for?

Did you click on the web site I posted? It tells you how to read the codes and what the 2 bolt engine mounts mean as far as the year ID goes.

Yes I went to the website, and it was very knowledgable, as for I went and checked the crank for some more numbers I found 2 letters (2u) and the stroke was about 3.75 I also think its .30 over the pistons say 30 and I think the bore was like 4 1/8

Robert you should see a 2U or 3U on the edge of one of the cranks counterweights if it's a 390 crank. There are some 13+ numbers in most books but the 2U and 3U by far the most common I've seen other than some early examples. 2T and 2TA can be found on a shorter stroke 360 crank. The rods are the giveaway here as the 390 used the short rods and the 360 the long rods.

The 3E4 is the date code of 73-May-4th. The 2 dots under the 3 tells it's a 73 block. The dots started in 69 to tell the difference between say a 59 and 69 block. Although there are other visuals to tell. The ribs are very common to 69 and later FE blocks. The ribs went away towards the end of production in 75-76. The block has both early and later motor mount provisions and actually there are 4 mount holes total. This covers early and later configurations.

The heads are lowriser heads and very good by factory standards. Those heads were used from 64-65 and the C6AE-R replaced them in 66. Your engine would have come with the D2TE-AA heads which replaced the earlier C8AE-H's. The C4 heads only have the 8 bolt vertical exhaust pattern. C6 and later heads used the 8, 14 and 16 bolt patterns depending on the application. So depending on the vehicle it's going in and the exhaust manifolds used might limit your choices. Most aftermarket headers have 16 hole flanges and will not be a problem to use in the right application.

So look for the 2U, 3U, 2T or 2TA. If you see by chance a 1U or 1UB it's a 3.98 stroke 410/428 crank.

If everything is in good shape you did good for $100.

Well thanks guys! I'm sure its a 390 now, you guys seem pretty knowledgeable and I appreciate it! Thanks! Its going in a galaxie too I'm not sure what the heads are on it. I have 2 360's and a 352 to pull parts from but all of the parts look really clean.