I was at the Welding shop today getting some rods that will weld to cast and the Welding guy told me that it is next to impossible on some cast metals to weld them to mild steel. I have read many articles on the net where people do it but is there a trick to it? I am having a friend of mine weld it up for me but just in case he doesn't know Do I need to preheat the cast part, or is the guy at the welding shop just blowing smoke.

Thanks for the help

1982/1992 CYJ "FrankenJeep" SOA with Waggy Springs 1" body, 4.0 head, borla headers & cat back, mopar MPI, Jacobs ignition, York air, Custom 3" intake w/k&n, K5 heater, Flexlight fan, 33" Coopers, DANA 44's, lockright up front, NP 435...In progress.