The small hole is an oil spit hole to provide oil to the major thrust side only of the cylinders and has nothing to do with detonation whatsoever. We provide oil to both major and minor thrust sides by way of conrod side clearance, alleviating the need to put a hole in the side of the conrod, which weakens it considerably. I would be very wary of an “engine builder” who was not familiar with the purpose of a spit hole in a conrod. Ford have included them since 1964 in 6 cyl engines.