[Toby]

Recently stroked out my 302 to 347. The car has less than 100 miles on it and while driving last evening, lost power, big lots of white smoke out passenger side pipes and engine starts clanking, so I shut her down. Upon inspection find #3 cylinder has mashed spark plug and stuck valve! After removing head notice absence of #3 piston and bent rod! plus 2 large holes in cylinder walls. Engine builder says cylinder walls look awful thin 1/8 ". This was an existing 0.30 bore that had run fine as 302, with about 4000 miles behind it. Any ideas about other possible causes?