I bought a set of billet steel 4 bolt main caps to convert my 2 bolt. Machine shop is telling me that the billet ones are not as good as nodular steel ones, because its a differant material. They would expand/contract at differant rates. Makes sense, but the crank is forged, the block is cast, heads are aluminum, I mean the all the componets are going to change differantly. Are they blowing smoke up my butt, or being overcautious? Any of you guys hear the same?

 

Sounds to me like they don't know their sh*t... call another reputable hi-perf shop and see what they say.