I have a question about (new) flat tappet hydraulic lifter installs, with a new cam and stock non-adjustable arms.... In the past I have just lubed them up externally, put them, and and ran them. I have also pre-pumped them up (full) with oil to avoid that initial clatter.
Now I am reading about pre-load specs but they all seem to be with adjustable rockers. Does it really matter either way with non-adjustables? Not a high lift cam @ under .50" .
It is a 340 if it matters.
:wrenching:
It depends on the machine work & is worth checking for sure , you need to measure the distance the piston inside the lifter is depressed when the rocker gear is tighten up , the only adjustment is the pushrod length .
Correct you need to be on the low point on the lobe to check , less depression is better too limit pump up , I believe the lifter travel is about .060 , best to be in the .020 - .030 range , there should never be play !
You have it right .020 below the clip , preloaded , no play
Sounds about right. Take a lifter apart and you'll see how much travel is available. 1/4" sounds about right on brand new empty lifters.
Once you have oil pressure, that cavity will fill up and make the lifter act 'solid'
Just an FYI...
My Lunati camshaft came with instructions for measuring the pre-load.
It states to lay a flat edge on the valve cover surface of the head and to scribe a line on the pushrods. Then to remove the rocker assembly BUT NOT the pushrods and that they will rise as the assembly is removed due to the oil pressure in the pushrod being relieved, and scribe a second line. The difference between the two marks on each pushrod is the amount of the preload. They say preload of .020 to .060 is recommended.
@chargerdon (https://forum.e-bodies.org/mlist/chargerdon_451) I will try that method today. I don't have one of those push rod checkers and that sounds more accurate than a dial indicator on a somewhat wobbly rocker arm.
Thanks
Quote from: chargerdon on August 28, 2021, 07:24:31 AM
Just an FYI...
My Lunati camshaft came with instructions for measuring the pre-load.
It states to lay a flat edge on the valve cover surface of the head and to scribe a line on the pushrods. Then to remove the rocker assembly BUT NOT the pushrods and that they will rise as the assembly is removed due to the oil pressure in the pushrod being relieved, and scribe a second line. The difference between the two marks on each pushrod is the amount of the preload. They say preload of .020 to .060 is recommended.
At .045 sounds right on .
Preoiling will get some oil into the lifters but the valve will still open & the engine will run for the 10 -15 seconds or so it takes to get oil there .
pre-lubing with a drill will fill voids with oil, but not create any real oil pressure. The drill might make 5-10 psi of oil pressure (I've never put a mechanical gauge on during pre-lube. I just spin it till I see oil flowing out the rocker shafts.) the real oil pressure will come from the oil pump when the engine is at 1000 rpm or better.