I've stick welded it a few times.. Never an cylinder head,,, but here's a few things to look for.. First, and MOST importantly,, you have to PREHEAT the area around the "crack" or hole or whatever you plan on filling up... There are certain "sticks" that are made out of plastic or wax that let you know if it is hot enough to work on... A welding supply store would be your best bet.. Ask them,,, they sell stuff for cast welding all the time... Certain rods you need.. I think they are called NYROD.. There is also a cast iron rod available.. The SECOND MOST IMPORTANT thing to do is,, after you weld it,,, you NEED TO wrap it up in a welding blanket and STICK IT in an oven (like the one at home) and BAKE IT for an hour or two (the more the better) to get the temperatures consistent throughout the entire piece your welding.. THEN TURN THE OVEN OFF and leave the part wrapped up in the blanket,, in the oven,,, OVERNIGHT!!!! It needs to cool down VERY SLOWLY AND EVENLY.... This is when your weld job WILL CRACK because of the different density's of the weld compared to the cast area around the weld... Just as cryogenic treating (three hundred below zero) tends to "stretch out" and "relieve tensions" in the metal,,, using the COOL DOWN SLOWLY approach tends to act SOMEWHAT the same way with welding cast... It CAN BE DONE,,, if you take your time and do it RIGHT!!!