Originally Posted by xdclevo
I am trying to adjust my rollers so i can put my motor in tonite. I have a F246 solid, and it says to go 26 thou hot, which will be 20 thou cold(alloy heads). Each time i set at 20 thou, and rotate the motor to do the other, i get back to number 1 again, and it is about 30 thou. Is there a trick????? Do i set at 15 and then it goes to 20(probably not).. I have yella terra yt5006 and 7/16 screw in studs, and crow 80thou heavyduty pushrods. Is there a trick to do with the set screw. I did notice when i set at 20 th and lock up the set screw, it imediatly seems a bit looser(a few thou). Thanks Dion.
There is a "trick" to it and you're just missing it. Do what you're already doing...then...tighten the set screw tightly (but don't kill it). Then tighten the lock nut without touching the set screw to take up the additional slack and you're done. It will also ensure that they don't work themselves loose.
There is a bit of space between the threads of the stud and the lock nut. When you tighten the lock nut against the rocker fulcrum, the pressure of the pushrod/valve against the rocker press up against the bottom of the lock nut and against the bottoms of its thread surfaces. When you tighten the set screw down against the stud, it slightly raises the lock nut and produces your error value. When you tighten the lock nut a bit more, it will take up the additional slack.
If you're unsure of whether or not you're on the base circle for a particular cylinder, turn your dampener/timing pointer to line up with TDC or -0- degrees on the dampener. Cylinder 1 will be on its base. Rotate the engine clockwise 90 degrees and adjust the next cylinder in the firing order. Rotate the engine a full 360* twice to cover all 8, stopping every 90* to set the next cylinder in the firing order.
A wee bit too loose lash (as long as parts aren't banging the hell out of themselves) isn't the end of the world, in fact, your torque readings will improve! However, you need to be more concerned with a rocker arm backing off its lock nut and deciding to flail around inside the valve cover, which isn't good for pushrods, poly locks, rocker arms and any nearby valvesprings.