We broke in my 434 on Renegade Crate 98 race gas, checked the valves, made a few pulls to get the jetting and timing right. After all this was done and we had the best results on the 98 we pumped the fuel cell back into a can, drained the bowls then refilled the fuel cell with pump 93. After warming up on the pump gas the first pull was 30 more hp than the race gas. I thought it was a fluke so they cooled the engine down and made another pull, 30 more hp again.
