60 over would be a 468 but it would need sonic checked to make sure cylinders don't distort.

 

I would not waste my money on sonic testing at.060 on a BBC.

 

most but not all 454's can go to .125 over. block must be sonic tested for wall thickness
what it's worth depends on the quality of the components and 2bolt vs 4bolt main
I would have no issues with a .060 454 ever

 

There are uncountable numbers of aftermarket hot rod built 502's with a 4.470 bore built out of Mark IV and MarkV 454 blocks. Retaining their 4 inch stroke EXTERANLY balanced cranks

{Corrected}

Going from a 4.25" bore to a 4.47" is doable. So a mere 60 thou. ain't squat.

 

There are uncountable numbers of aftermarket hot rod built 502's with a 4.470 bore built out of Mark IV and MarkV 454 blocks. Retaining their 4 inch stroke internally balanced cranks

Going from a 4.25" bore to a 4.47" is doable. So a mere 60 thou. ain't squat.

All GM built Mark IV 454 are externally balanced

 

So when push comes to shove, is a IV better than a V, which is better than a VI?

 

V and VI use one piece main seals, roller lifters, no mechanical fuel pump 4 bolt mains and steel cranks

 

Not all V and VI are steel crankshaft.

 

I had no knowledge of any one piece main seal cranks made out of iron. Now I do, what PN would those carry?

 

FYI: IN Midwest, I gave my mark IV 454 std bore, with 781 heads, pile of parts for free. Included 427 steel crank. Took 3wks to give it away. Sold NOS LS7 steel crank $300, NOS LS7 pistons $300. Will not buy BBC parts again, unless restoring a factory BBC car.

 

Wasn't there something about the Mark 4 heads not sealing on the Mark 5&6 blocks seems like I had heard that but wasn't sure it that was the case?

 

it's the opposite, I think. you need special head gaskets.

 

All cast crankshafts are cast steel - no cast iron.

 

All cast crankshafts are cast steel - no cast iron.

As I said earlier,

V and VI use one piece main seals, roller lifters, no mechanical fuel pump 4 bolt mains and steel cranks

 

cast steel isn't the same as forged for sure.

 

I never said, implied or hinted it was a forged steel crank.

 

Here's some pics of the 454 in question. I found out the engine belongs to a customer that may be willing to sell it. The shop owner told me he has a 396 or 454 in his back room. He does know it has a steel crank. He doesn't know what to ask for it.

 

Cast crank, narrow parting line. If shop calls that forged......RUN RUN AWAY

 

the crank pictured is cast not forged. and the pistons pictured are cheapo poor dome shape junk pistons. offer him 500 tops.

 

Thanks. I'll seewhat he has in his back room.

 

Sure its not a late 402 instead of a 454.