Originally Posted by spinn
Tryingto figure out if that could occur by the method i use.
Not contradicting your information. Didnt mean to imply you said anythjing. Those are my theories, or what ifs.
My thinking , some engine revs up and drops oil psi. Then the plunger relaxes and creates this pushrod/rocker clearance . So you compress the lifter plunger with preload to allow a saftey margin for this occurance. Is this wrong, or do not get the prupose of preload?
Lose has one o. I think it is like look,or took. The oo sound in loose. Nevermind, stupid thought. Neither here nor there really.
Using your method (zero lashing w/o any preload) works. It has been used for years by racers who anticipate their engine will experience valve float, which is one main way for a hydraulic lifter to pump up. If there is no clearance to allow the plunger to pump up, there won't be any chance the valve will be momentarily held off its seat causing the engine to lose power, or worse.
Oil won't compress, so as long as there's enough oil pressure to replenish what is 'lost' to the top end through the pushrod (to lubricate/cool the rocker and spring), the lifter won't pump down. The way the valving is arranged in a hydraulic lifter, there is oil being released to the top end of the engine only during the time the lifter is dropping and the valve is closing. That is unless the lifter is an "edge orifice" type, which isn't seen much anymore.
Bottom line is there is no down side or loss of lift when using 1/2 turn past zero lash on a hydraulic valve train if the valve train is assembled correctly and the engine is operated within the design limits of its components. Unless of course you are using special lifters that require a different method to adjust, like some
Rhodes and other fast bleed lifter designs.