The problems we had were machine swarf leftovers remaining in oil passages and eventually making way to, and blocking/partly blocking bearing feed holes in crankshafts leading to bearing and crank journal failure and swarf embedment in the bearing causing crank journal damage.
Better attention to cleaning the machineings out of the passages prior to asembly would have prevented this.
We changed to Repco Newcastle supplied engines and had no problems from there on.Interestingly, I don't think Repco Newcastle do engines anymore ??.
The acid tank process strips paint and oils/grease/dirt/ etc but the block just sits there happily boiling away and the water jackets don't really get flushed out just by hot tanking alone.The block should be pressure washed after hot tanking to remove sludge/rust etc that the hot tank doesn't remove.
Your radiator core will love you for it!!


