I thought I had a 428

[Jrpumper]

I bought a  of fe parts from a guy tryn to clean out his garage , I bought what he said was a 390 when I got it home I took my book I have to identify the engine I was very very happy to read what I read by the numbers on the block it said to be a 428 I checked and double checked  when it  came time for a engine build in my 62 Galaxie  their was no question which it was gonna be , I took the engine to my builder  , 2 hours later he called me back and told me. Some upsetting news that what I. Really had was 390 4 v engine  , so I brought my book and showed him what I did, me engine builder is very good he has been in business along time , it blew his mind also.....has anyone ever heard of this before. I have a 390 with 428 markings...........

[KMcCullah]

First post for you! Welcome Jrpumper.
Yea I've had my hopes up a few times with a couple of blocks. When it comes to FE blocks, there isn't much on the outside surfaces that you can use for identifying. Maybe a C or A scratch on the back. But the best way to see what you have is with a set of dial calipers. Measure the bores. The drill bit test between cylinder walls will give you a clue also. And then to make sure you don't have a 352/390 thats been punched to 428, get a sonic map done at your local machine shop.

[cjshaker]

I bought a  of fe parts from a guy tryn to clean out his garage , I bought what he said was a 390

Well, on the positive side....he didn't lie to you
There are plenty of guys who would try to pass off a 390 block as a 428 based on "the numbers". If you were using Steve Christs book, forget about the part numbers in it. Most of them are useless.

It can be nearly impossible to determine a 428 block by looking at it. Except for early 332, 352 and 390 blocks which use the earlier cam thrust set-up, all FEs pretty much look alike, or can look different even within the same CID engine. They can be all over the place with different casting molds used. Like Kevin said, beyond the rear A or C scratches, which not all of them had, it would take some serious investigative skills to determine bore diameter and cylinder wall thickness to determine what it actually is....or what it COULD be.

[FishCakes428]

Look through, I think. one of the center core plugs or down through the rear water jacket openings at the rear. You will see "428" cast in the floor at the base of the cylinders. BIG NOTE: The numbers can be difficult to see. I shine a light in from one of the core plugs or from the water jacket openings at the decks. When you get the light just right, the numbers will sorta cast a shadow off themselves. IIRC shining a light directly at the numbers might make it more difficult to see.  If "428" is there, you will see them.  Good hunting

[428GT500]

Often the 428 can also be seen though the deck surface  at the water jacket passage.  I have been lucky, as I found two different blocks with wall thicknesses of over .240 post sonic mapping, which will easily go the .080 over to the 4.130 bore.

                                                                                                        -Keith