One other question, in the blog post on lifters it says "If there is air trapped in the reservoir it will move to the bottom of the reservoir as it is lighter than oil." Why would this make it go to the bottom rather than the top? Or am I misunderstanding something?
Tim
From my blog.
"The problem comes in when all the air is not removed on assembly.
What appears to happen at higher RPMs is that as the lifter reaches the maximum height of the cam lobe and starts back down
inertia keeps the oil moving towards the top of the reservoir. If there is air trapped in the reservoir it will move to the bottom of the reservoir as it is lighter than oil. From there it will enter through the check valve into the lower working area as the lower working area of the lifter recharges on the downward travel. This gets the lifter ready for the next valve opening. This air that has now entered the lower working area of the lifter makes the lifter spongy and creates lifter clack.
Once the RPM's are reduced and the oil again stays in the bottom of the reservoir, the air bleeds back up from the lower working area between the plunger and body, back into the reservoir, and the lifter will quiet back down."
