I just finished tearing down the engine from my '69 F100. You may recall that I always thought it was a 360 ("Y" code VIN, seller told me engine was original, no apparent performance mods, 2v intake and carb, etc.). When I removed the heads last weekend, though, I measured the stroke for the first time and discovered it was 3.78". Cool, a 390!

Wrong. It's been sitting on the engine stand in my garage since Saturday, and I went out after dinner tonight to finish tearing down the block so I could take it to the machine shop tomorrow. The first thing that caught my eye was the part number - C7ME-A. That sounded familiar. I tore it all down, and the pistons looked a little large to me. I miked the bore - 4.16"! So I went and looked up the number. Sure enough, both Steve Crist and George Reid list the C7ME-A block as being a 67-68 428.

In other words, I've got a 428 that's been destroked with a 390 crank -- a 406. It's .030 over already, which makes actual displacement 411. Of course, I have a freshly ground .010/.010 428 crank ready to go in. Instead of having a 410 when I'm done, though, I'll have a 428. How bizarre is that?

The parts in the engine were quite a mishmash. The crankshaft is a standard 2U 390 crank. Five of the connecting rods are C7AE-B rods, which are listed in my books as being used only on the 66-70 428 police and Cobra Jet motors. Two of the rods are C3AE-C (listed as 63-65 427), and the 8th rod is a standard 390/410/428 C6AE-C.

The really good news is that the bores look great. I think I may get away with just honing them. I discovered the reason for my low compression on two cylinders, though -- both pistons had broken rings.

 

That is pretty cool. At this point you are going to have the block sonic checked right? Even though the C6ME-A block is supposed to be a 428 block, I have seen many plain jane 390's with the same casting. At 4.16" I'm betting you do have the CJ block though.

 

My references list the C6ME and C6ME-A as being both 390 and 428 blocks, but the C7ME-A is only listed as a 428. In any case, it's either a .030 over 428 block or a .110 over 390 block. The latter is pretty unlikely. I will have it sonic checked if it needs to be bored, but the cylinder walls all look great, and there was no ridge at the top, so I'm hopeful that I'll get away with just honing them.

 

I misread your first post I guess. I have never seen a C7AE block before but I have never seen a 428 block either so I suppose that is good. Hopefully it doesn't need bored. You can actually say you have a 428 with a straight face.