Please bring back Alex, with the Datsun pickup, whose mechanic told him he had dropped a valve. I had a 720 that broke two cams. If that head warps, the cam tower bosses are at uneven heights, and the cam literally flexes as it turns. The cure is to pull the head,mill the bottom flat, turn it over and mill the cam bosses to identical heights, then replace the cam and perhaps the towers. Otherwise the new cam will break very quickly.