Lifter preload...more or less?
Sealed Power made anti pump up lifters.....& std lifters. HT-2011R & HT-2011 respectively for the SBM. They are identical except for the circlip design.
This is what it says: 'A special high strength steel retainer is used in place of the spring clip to precisely limit the travel of the plunger...'
The hot lash with these is set at 000/002". I have seen these pop the circlip.
The purpose of these lifters is to limit pump up [ hence: anti p/up ]. The problem is that the circlip is gets pounded as the lifter tries to pump up.....& stronger though they are, they can & do pop out.
Majority of hyd lifters have about 0.150" internal travel/pre-load. Setting pre-load anywhere within this range [ 0-0.150"] will provide the same engine performance & there is ZERO benefit setting lash with 010" gap to the circlip, & to do so will almost guarantee popping the paper clip type circlip used with stock lifters...& the possibility of lifter bits through the engine. The proper way to limit lifter pump up is to keep rpm below the start of pump, use stronger valve springs or use sol lifters that are tight lashed.
No car company, including Chrys, used zero lash from the factory because of the above danger.