The trick was to shut off the car as soon as possible while negotiating the race spot.....It was a common trick to "adust" the hydraulics with special lock nuts using the Royal Pontiac tune up kit to get full travel on the cam...This would make the lifters"tick"..or at least, that's what I would tell people LOL !!! Remember, almost nobody even heard of a 421 Pontiac in 1961 much less saw one in person...The engine was only available over the counter and was VERY expensive !!!