bananafancandle
06-07-2021, 03:15 AM
After taking a brass wire wheel to my cylinder head, it's in need of a more professional touch. Talking to a machinist, we realized the BMW guides state "no machining possible." Does anyone know what this is about? I just dropped $600 on this head, cleaned every port and valve, and ceramic coated it, so I don't want to just turn it into a coffee table.
My assumption is that the piston-valve tolerances are just too close. Only other things I could think of are compression ratio and cutting into the valve seats. I have 4 thou warpage and the machinist told me it could take 8-10 to fix that. He was also saying valves would need ground but I couldn't really understand why. Anyways, I've got a dial indicator on the way (needed an excuse to buy one) to measure all the tolerances going on so I can try to rule out why machining isn't permissible, but maybe someone more experienced could chime in. Maybe if I'm lucky I can just get a thicker head gasket. $120 is a hard lesson, but $600 and hours of work...
My assumption is that the piston-valve tolerances are just too close. Only other things I could think of are compression ratio and cutting into the valve seats. I have 4 thou warpage and the machinist told me it could take 8-10 to fix that. He was also saying valves would need ground but I couldn't really understand why. Anyways, I've got a dial indicator on the way (needed an excuse to buy one) to measure all the tolerances going on so I can try to rule out why machining isn't permissible, but maybe someone more experienced could chime in. Maybe if I'm lucky I can just get a thicker head gasket. $120 is a hard lesson, but $600 and hours of work...