The 20r head was not replaced. The head gasket was replaced along with the other seals/gaskets for the top end that came in a kit. This was done to combat an overheating issue. With this I was successful. The head was checked for flatness and the valves and springs checked too. All appeared well and the same head, valves and springs were installed. The valves were adjusted after install. The piston rings have been slowly dying for some time. I have low, but equal, compression. I suspect that this is the problem as well. I just cannot believe how suddenly the mileage dropped from the tight seal. I will no more when I calculate my mileage from my latest tankful with all the previous adjustments made.
