A newly minted FJ60 owner here. Please bear with me.  rove my 1983 FJ60 to DC from Utah. Along with a recent 2F engine rebuild, a Weber 38/38 carb was installed. When driving up hills at 60-70 mph, I noticed very audible valve rattle/knock. The rattle would subside when I backed off the throttle and in turn backing down to turtle speed. Using premium grade gas seemed to reduce the rattle. Question: Would carb adj be necessary due to change in altitude from Utah to VA? Would adj the carb be a potential solution to the valve rattle? Any suggestions are appreciated. Thanks!