Any one have any thoughts or musings on this subject??? A few years back when I built my first engine with adjustable roller rockers (351w), I read to preload the lifters anywhere from 1/2 turn to 1 and 1/4 turns, depending on different sources. I started out at 3/4 and later on went back in and changed it to 1/2 and there seemed to be more power at 1/2 turn. I havent really gave it any thought untill lately, mainly because I just assembled 2 more engines this spring- another 351w, and a 400- that both have adjustable roller rockers. A guy I work with told me he only turns his down about 1/8 turn, and that got me to thinking about this procedure. Seems to me this whole hydraulic lifter idea is a terribly "flawed" way (for lack of a better word) to dial in what is supposed to be an precise engine event. The biggest issues to me are that the lifters are "pumped up" by the oil pressure in the engines system- oil pressure can vary a lot, obviously. Plus you have all these different sources telling you different preloads, different valvesprings, rocker ratios,blah, blah, blah!!! I've rambled on enough-- any thoughts or enlightening facts??? I think today I will go out and try some different preloads on the 400 engine if I get enough time.

 

The proper pre-load is a published range in thousands/in. (Crane or Edlebrock has an excellent article on their site all about it.) The right way to measure it is with a dial indicator, but there are other methods. This is a right/wrong choice, not better or worse. Hydralic lifters make life simple and work fine. Setting the pre-load can be a PIA, but it just takes patience. Not high performance but you don't have to pull the valve covers ever 10K and adjust the valves like I had to do on my old Spitfire. My .02 Cheers

 

Oil pressure does not have anything to do with lifter "pump up" per se unless you don't have any oil pressure. Oil is used to fill the plunger cavity in the lifter. Oil is essentially incompressible (about 4%) and is just used to take up slack in the valvetrain which varies due to wear and temperature. The oil does leak out slowly while the lifter is under pressure from the cam and spring which is why new lifters work better than old lifters and the fast bleed lifters leak off fast enough to change cam timing when they are new.

 

Easy way to do lifter pre-load:tdc on cyl you are working on,get it to zero lash,(look at the lifter itself and you will see the plunger move down)then with the torque wrench it should only turn 1/2 to one full turn to torque specs.If not use the shim kit.
I was freaking out 'cause half the people I know said "Don't worry about just torque it down". The vavle train will last longer and smoother with the right pre-load. It took some research and help,but I figured it out.

 

I'm with you on that one.

I'm trying to figure out, though, if Wyld is talking about the pedestal mount rockers you're speaking of or he had his heads converted to stud mount. (or aftermarket heads)

 

when i adjust my rockers, i use a valve cover that is cut open and then i can put it on it and put my wrench in

i start the engine at idle and i listen to it, then i can rev it and oil wont go everywhere... ill drip a little but its not bad... now the engines i build are not for looks, all the engines i have built have been for circle track or my work trucks..

if your building the engine and dont have it installed the best way i think to do it is to tighten the rocker till you can see the rocker start to push down just a little, then i wiggle the rocker side to side and check for lash, then i would deside if it was tight enough to put a 3/4 turn on it and most of the time its perfect, i might do slight adjustments with it running, but this should work'

Matt

 

For stock pedestal mount rockers.

 

This is what I do also. I got a valve cover from the bone yard and cut the top out....There you go...A custom valve adjustment valve cover. I also use it to adjust the valves while the vehicle is running. This helps me to find the "sweet spot". Some people say "the right way or the wrong way", but this is open to interpretation, and I say the "right way", is the way that works.