[Old182]

George has it right. I just posted on another thread that studs have 2 different classes of fit. The coarse end should have a Class 5 fit which is an interference fit. The studs I've seen from the Model A supply houses are not Class 5 on the coarse end and can be easily screwed into the block - studs should have to be "driven". After 80+ years of heating, cooling, corrosion and erosion, it's no wonder the threads are somewhat loose, particularly if the new studs are rolled to a Class 2 fit. Perhaps a "real" fastener supply house would have the correct fit studs for our applications. All that said, I replaced a worn (loose) stud with the 1/2-13 repair kit from Snyder's and it's worked quite well for several years now; you might consider that route if nothing else sounds reasonable.