When checking valve to piston clearance, I like to either completely bottom out the pushrod in the lifter, or use a solid lifter at zero lash. Hydraulic lifters collapse very easily if they are new ones right out of the box, even the checking springs can push the plunger down and throw off the readings.
We seldom check valve to piston clearance unless the cam is a really high lift, long duration solid roller. The small hydraulic cams aren't going to have the valves close to the pistons, so it's an added step that really isn't needed for mild builds.
If and when we check the clearance, it's done with no head gaskets, and the valve lash at zero. This way we automatically know that we have .039" plus .022" (.061" for example) if the engine turns thru freely without valve to piston interference.
Good idea as shown to adjust lifter preload before installing the valley pan. It's easy to screw this up and not get on the base circle of the camshaft. I alway like to look right at the cam to see that the lifter is well on the base circle when I set the pre-load. Following the firing order, or going by the 180 degree set 8, then 180 set 8 more method is fine, but it's easy to miss one, or get confused, etc. There is no confusion when you are looking right at the lobe and make sure it's close to 180 degrees from the lifter when setting them.....Cliff
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https://cliffshighperformance.com/
73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile),
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