Industrial 427 Blocks

[mike7570]

That's what I thought, Thanks
I still need to have it sonic checked. It's currently at 4.16 and if it's a 390 block I'm guessing the walls are pretty thin.

[wsu0702]

I agree it looks like a "C" but because it's a C4AE-A casting I wonder if it is a poorly formed "G" for July.

Did you check for the small pipe plug in the block skirt just above the pan rail on the passenger side?  All of the evidence so far is pointing to a thick walled 361/391 FT block (1964 was the first year for the FT engine) and if so it will have that plug.   
 

[mike7570]

No pipe plug and my FT distributor bushing won't fit in the distributor hole. So now it looks like a cross bolted 390 block?
I think I will get it in to a shop in the next couple of weeks and have it cleaned and sonic checked.

[wsu0702]

No pipe plug and my FT distributor bushing won't fit in the distributor hole. So now it looks like a cross bolted 390 block?
I think I will get it in to a shop in the next couple of weeks and have it cleaned and sonic checked.

Yes a sonic check will tell the story and it is most likely one of the very common C4AE-A 390 blocks cast with the 427 lower end casting features (cross bolt bosses, extra main support webbing and thicker cross-sections).  The fact that you said that you could only fit a 13/64" drill bit between the cylinders inside the water jacket is intriguing though.  There were some 406 service blocks cast as C4AE-A blocks.