How big can it go?

[rebelrouser]

Guy dropped off a BBC block casting 3999289 It had valvetrain issues that is why he took it out. He bought a used drag car and the engine backfired on the first pass and died. Broke rocker studs, bent push rods, etc. So I don't have a history on how many runs it has. The block cleaned up nice and the cylinders have no wear, block is filled, my issue is that it has a bore of 4.370 if I do the math right that is .125 over. I have a digital long reach caliper, and through the water jacket holes at the top of the deck it measures from .270 to .220 cylinder thickness. And from my experience between the water jackets is where they are thin most of the time. I have never had a filled block sonic checked, will it still be accurate with the fill? And a shop that has one is a couple hours away. How big can a BBC go? I get nervous at .070 over.

I am trying to talk the guy into an aftermarket block, options would be a dart sportsman or a merlin, looking at the specs, I don't see a big difference between the two blocks, any opinions?

He wants a 750HP to 800HP power level, it has Brodix BB-2 heads, and a flying toilet on alcohol. so I think that is easily doable.

[KnightEngines]

I had one through that was 4.400" bore, ex blown alcohol engine that made around 1200hp.
It had obviously lived like that for a while with no real signs of duress.
4 bolt steel caps fitted, grouted etc.
Seemed ok, went back together as a milder street/strip combo.

[rustbucket79]

A sonic tester measures to the first interruption, as in it would only measure the thickness of a repair sleeve in a cylinder. The shop will accurately measure that block, and yes it will be thin between the bores, likely under .100” on several.