Oil burns BLUE
Gas burns BLACK
Water burns White
Recently rebuilt a 250 chevy block was warped .013, head took .023 to clean up. That is the main reason for continueing to blow head gaskets if you are torqueing to proper spec in proper order. If your engine mating surfaces are flat, on a stock engine any head gasket should work. Some gaskets compress to different thicknesses, but all should hold. also a small crack in the head or the block can cause white smoke, so if you examine head gasket and see no signs of a leak check for cracks. As mentioned above excessive timing advance or the wrong fuel can cause preignition which can blow a gasket but most stock chevy 250s should run on regular fuel if properly tuned.
