Correct using it at was the issue. But for out little 675hp pump gas deal was not concerned. I have sonic checked a bunch of stock blocks over the years and NEVER seen anything this thin. FWIW the rest of the engine looks great, well except the extra holes There is a reason I no longer use stock block deals in racecars. This was the engine from my 68D100 and was never meant to have 250 passes on it