cpenrose

Something I’ve been wondering, figured I’d ask and hopefully someone can learn me on this. If the lifters fill up with oil pressure and that’s strong enough to lift the rocker, what’s stopping that pressure from taking up the preload space and hitting the retaining clip? And therefore opening the valve slightly. Or am I missing something here

SS RRR

iTrader: (2)

Valve spring pressure is supposed to be constant on the plunger. The pre-load adjustment along with that pressure is what keeps the plunger off the clip. However, if the springs chosen are not correct for the cam profile, or they are weak/worn, or pre-load is not adjusted properly, contact with the two can happen.

Supercharged111

iTrader: (1)

Figure you have 50#ish of oil pressure pushing against the valve spring inside the rocker, divide that by 1.6 for the stock rocker and that ends up being 31#. Let's say for conversation's sake a stock valve spring is 85# on the seat. Multiply that by 1.6 and that's 136# pushing down on that plunger before a valve leaves the seat. It's not difficult to see why the valve spring wins.

Fast355

The valve spring definitely wins. Years ago in my first cam swap at 16 years of age, I tightened the rocker arms actually tight enough that as soon as the engine rolled over it had zero compression. I accidentally pre-loaded the lifters all the way. Valve spring pressure will completely collapse the lifter. With adequate valve spring pressure, you actually want the plunger deeply set into the lifter body to maximize lift. Look at Holdeners LS pushrod length test to show the effect of deeply pre-loading the plungers on performance.

cpenrose

I think what I was missing is the fact that it’s pushing against the check valve in the lifter not just oil pressure. And oil pressure is just to take up lash