Thread: Virgin Engine C5AE-A

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I recently picked up 2 core shortblocks. Both are C5AE-A castings and both have C4AE-B crankshafts. One has C7AE-B rods and the other has C3AE-C rods. One of these engines was a virgin block. It had FoMoCo bearings.

Now these blocks have a casting # that could make it a 390 or a 427. Cross bolt bosses are unmachined. Both blocks are bored to 390 specs. One is standard the other is 0.030 over. I'm trying to determine if these engines can be bored to 427 specs. Has anyone here had experience boring a C5AE-A block to 427 specs?

I would doubt if they would bore that far. Sonic check.

I agree. Most casting numbers are generic and used on many different bore blocks. The C5AE-6015-A is one of them as you see. I have seen some of them go to 4.13" std 406-428 bore but 4.23" would not be likely. And having the cross bolt bosses is a nice option to crossbolt w/factory or aftermarket caps. Some of the C5AE-A blocks were also solid lifter blocks used in the 390 PI engines. Some 352's had that casting number too. Dave Shoe's drill bit test will tell you aprox what you have for cyl wall cores. But as Shoprat said a sonic map is best for exact results. Nice find on that virgin. Not many of those around anymore.

Originally Posted by Duckie

I recently picked up 2 core shortblocks. Both are C5AE-A castings and both have C4AE-B crankshafts. One has C7AE-B rods and the other has C3AE-C rods. One of these engines was a virgin block. It had FoMoCo bearings.

Now these blocks have a casting # that could make it a 390 or a 427. Cross bolt bosses are unmachined. Both blocks are bored to 390 specs. One is standard the other is 0.030 over. I'm trying to determine if these engines can be bored to 427 specs. Has anyone here had experience boring a C5AE-A block to 427 specs?

Boring it to make it a 406 is do able and the 406's were not any thing to sneeze at performance wise.

Originally Posted by FFR428

I agree. Most casting numbers are generic and used on many different bore blocks. The C5AE-6015-A is one of them as you see. I have seen some of them go to 4.13" std 406-428 bore but 4.23" would not be likely. And having the cross bolt bosses is a nice option to crossbolt w/factory or aftermarket caps. Some of the C5AE-A blocks were also solid lifter blocks used in the 390 PI engines. Some 352's had that casting number too. Dave Shoe's drill bit test will tell you aprox what you have for cyl wall cores. But as Shoprat said a sonic map is best for exact results. Nice find on that virgin. Not many of those around anymore.

I was suprized to find it was a virgin block too. Very little rust in the cores and no sludge in the engine. Only problem I found was the #1 and 5 rod bearings were 10 miles away from spinning. Other than that the crank was perfect. But it should clean up at 0.010 under.

I did the drill bit test and if one of those blocks can be bored to 427 spect it's the virgin. Slightly bigger gap than .180" between the cylinders. I'm gonna get is sonic checked and I have my fingers crossed. The other may only be able to go 0.060 over 390 specs. Lots of rust in the cores of that one. When I got it all 6 core plugs were rusted through. That one is a good candidate for a muratic acid bath to get rid of the rust. That block is already 0.030 over and may be junk but at least the crank and rods were good.

.060 always worked good for me. My 4000lb Ranchero ran 12's with a .060 390
for years. It took a 427 and a lot of money to get it in the mid 11's.