"GRUMPY? why does the hydraulic lifter preload matter, 1/4 turn, 3/4 turn, I don,t see any reason it maters and does less preload result in less valve lift or more valve lift, Id figure that the more preload the less lifter plunger moves and the more valve lift?"
READ THIS THREAD
viewtopic.php?f=52&t=6491&p=20681&hilit=spray+springs+cooling#p20681
I don,t think you have a firm grasp on whats going on,during the mechanics of the lifters operation, the lifter seat is FULLY compressed to its seat as the cam lobe ramp spinning under the lifter base lifts the lifter off the cams base circle,and the lifters push-rod seat is compressed against the valve spring, oil trapped between the lifter, is forced up the push-rod until the lifters push-rod seat reaches its fully depressed location in the lifter body, this takes time and depending on the rpm levels it may not reach its full depressed seat location in the lifter body before peak valve lift, keep in mind that at 6000rpm the lifter is cycling from seated to fully open 50 times a second.
the lifter seat is forced back to its full upper location by a combo of engine oil hydraulic pressure and a small spring, this also takes time, hydraulic lifters will at some point in the upper rpm band fail to fully cycle, but generally continue to cycle once the rpms drop again.
the factory suggests 3/4 turn as it allows more compensation for wear in the valve train, and anything from 1/4-3/4 works but you get more valve spring cooling with 1/4
at low and mid rpms the lifter push-rod seat is fully depressed during the lash ramp and has little or no effect on total valve lift (see green line)this is mandatory as its how oil is forced up the push rods to lube the valve train,
at high rpms the lack of time to bleed oil up thru the push rods, and allowing the seat to fully seat might add insignificant lift, at very high rpms the lifter seat can,t collapse the plunger fully and it can cause the valves not to fully seat
READ THIS THREAD
viewtopic.php?f=52&t=6491&p=20681&hilit=spray+springs+cooling#p20681
I don,t think you have a firm grasp on whats going on,during the mechanics of the lifters operation, the lifter seat is FULLY compressed to its seat as the cam lobe ramp spinning under the lifter base lifts the lifter off the cams base circle,and the lifters push-rod seat is compressed against the valve spring, oil trapped between the lifter, is forced up the push-rod until the lifters push-rod seat reaches its fully depressed location in the lifter body, this takes time and depending on the rpm levels it may not reach its full depressed seat location in the lifter body before peak valve lift, keep in mind that at 6000rpm the lifter is cycling from seated to fully open 50 times a second.
the lifter seat is forced back to its full upper location by a combo of engine oil hydraulic pressure and a small spring, this also takes time, hydraulic lifters will at some point in the upper rpm band fail to fully cycle, but generally continue to cycle once the rpms drop again.
the factory suggests 3/4 turn as it allows more compensation for wear in the valve train, and anything from 1/4-3/4 works but you get more valve spring cooling with 1/4
at low and mid rpms the lifter push-rod seat is fully depressed during the lash ramp and has little or no effect on total valve lift (see green line)this is mandatory as its how oil is forced up the push rods to lube the valve train,
at high rpms the lack of time to bleed oil up thru the push rods, and allowing the seat to fully seat might add insignificant lift, at very high rpms the lifter seat can,t collapse the plunger fully and it can cause the valves not to fully seat
Last edited by a moderator: