Hydraulic roller adjustment question
04-24-2012, 08:27 PM
#4
Too much. On my Hydraulic roller I was at 1/16th-1/8th of a turn past zero lash. The more preload you run on a hydraulic lifter the more it has a chance of hanging a valve open at really high rpm by pumping up. I'm not talking about 6100 or 6200, but near 7k it can be a problem. It was adjusted once back in 2006 and I never had to touch them. They made zero noise and the motor still sits here patiently waiting for a new home. It saw 6900+ hundreds of times, stock lifters, chromoly pushrods, 918 beehives, 2.02/1.60 valves. The springs were installed at perfect height too. All of that stuff matters.
04-24-2012, 08:43 PM
#5
^ yes, be careful about overtightening. 1/2 turn is very significant.
That's almost .025" on a 7/16" stud (~.021 on 3/8).
Aftermarket recommendations vary from vendor to vendor.
Most of the engine builders that I talked to said 1/16 - 1/8 (For reference; 1/12th is rotating from a point to a flat)
Read this until you feel comfortable, then read it one more time.
http://shbox.com/1/4th_gen_tech2.html#adjust_valves
That's almost .025" on a 7/16" stud (~.021 on 3/8).
Aftermarket recommendations vary from vendor to vendor.
Most of the engine builders that I talked to said 1/16 - 1/8 (For reference; 1/12th is rotating from a point to a flat)
Read this until you feel comfortable, then read it one more time.
http://shbox.com/1/4th_gen_tech2.html#adjust_valves
Originally Posted by From the notes I made while building the 383
as RPM increases (4000, 5000, 6000 RPM, etc) and oil pressure increases, the lifter will "pump up" and the plunger in the lifter will come to the top. This has the lifters preload battling against the valve spring pressure.
It can cause it to bang at high RPM, lay over at high RPM, etc.
It can cause it to bang at high RPM, lay over at high RPM, etc.
Last edited by James Montigny; 04-25-2012 at 07:40 AM.
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04-25-2012, 11:23 AM
#10
Too much. On my Hydraulic roller I was at 1/16th-1/8th of a turn past zero lash. The more preload you run on a hydraulic lifter the more it has a chance of hanging a valve open at really high rpm by pumping up. I'm not talking about 6100 or 6200, but near 7k it can be a problem. It was adjusted once back in 2006 and I never had to touch them. They made zero noise and the motor still sits here patiently waiting for a new home. It saw 6900+ hundreds of times, stock lifters, chromoly pushrods, 918 beehives, 2.02/1.60 valves. The springs were installed at perfect height too. All of that stuff matters.
1/16th -1/8th turn on mine. 7000-7100 shift points.
04-25-2012, 12:01 PM
#11
You can run .130 preload and as long as you don't lose control of the valve it will make more power as the litter cannot bleed down. However if you unload the lifter with valve bounce, loft, etc you will probably have ptv interference and some expensive repairs. I run just off the solid height when cold (in the 30s) with .017" lifter travel.
04-25-2012, 12:21 PM
#12
You can run .130 preload and as long as you don't lose control of the valve it will make more power as the litter cannot bleed down. However if you unload the lifter with valve bounce, loft, etc you will probably have ptv interference and some expensive repairs. I run just off the solid height when cold (in the 30s) with .017" lifter travel.
04-25-2012, 12:30 PM
#13
You can run .130 preload and as long as you don't lose control of the valve it will make more power as the litter cannot bleed down. However if you unload the lifter with valve bounce, loft, etc you will probably have ptv interference and some expensive repairs. I run just off the solid height when cold (in the 30s) with .017" lifter travel.
04-25-2012, 12:58 PM
#14
IMO the critical thing that gets neglected in these conversations is the definition of "zero lash".
A LOT of references say "spin the pushrod till you feel resistance" and that will nearly always endup being way past zero lash.
Far as what I have run I have run everything from 1/8-5/8 and couldn't tell a difference but I had use good valvetrain.
As said super low preload is about minimizing valve bounce when the valvetrain is on the ragged edge of control or beginning to lose control. I understand the idea behind a lot of preload like wicked94Z is saying but never tried it.
If you just go 1/8-1/2 a turn it is simple, no worries. "just set it and forget it"
A LOT of references say "spin the pushrod till you feel resistance" and that will nearly always endup being way past zero lash.
Far as what I have run I have run everything from 1/8-5/8 and couldn't tell a difference but I had use good valvetrain.
As said super low preload is about minimizing valve bounce when the valvetrain is on the ragged edge of control or beginning to lose control. I understand the idea behind a lot of preload like wicked94Z is saying but never tried it.
If you just go 1/8-1/2 a turn it is simple, no worries. "just set it and forget it"
04-25-2012, 03:01 PM
#15
Bleed down rate varies with oil aeration, oil pressure, spring pressure, total mass of the valvetrain, and lifter acceleration (side loading and body flex). If one wanted to minimize bleed down I'd run a billet body lifter, maximize the cam base circle, run high oil pressure with a thick oil, and run an oil restricting STIFF (3/8"+) pushrod. Like I said, ANY loss of valve control will pump up the lifter and cause big problems running a bottomed lifter, need big springs and big pushrods to keep it an impossibility.
04-25-2012, 06:08 PM
#17
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As long as meticulous attention is paid to spring pressures there should be no problem running stock lifters at minimal lash.
04-25-2012, 06:13 PM
#18
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I have seen on many of my builds through the years that the lifters generally bottom out fully at 1and1/4 turns majority of the time. Now I run the 96 LT4 7/16 studs with the full roller lifters S/A, on those studs is a stud cap that u torque to 18 ft lbs and forget it. Very easy to do...no guess work never a problem in six years. And i will still be using them with the pac 1218 springs and 503.
04-25-2012, 09:33 PM
#20
You reach this point when all of the slack is removed, not when you've squeezed so hard that there is friction between lubricated parts.