Setting up pushrods

[Hef5.0weisen]

For those that have set up pushrods, rockers etc....looking for some info.

Found multiple how-to type articles, even used the coveted search function on here, and as always ton of good stuff to be read.

More to the point, I'm wanting to know what the "adjustable" portion of stud mount rockers is...looks to me like you can move the fulcrum up and down on the stud...so what would that do for you.?

Also, the hydraulic lifter portion, my understanding is the lifter body fills with oil under pressure, moves a piston inside the body, this in turn keeps the slack out of the valvetrain??

Not trying to reinvent the wheel here, as this stuff has worked for decades, but those variables seem to undermine proper length...seems they would compensate....

Also curious about determining proper length if the lifter is depleted of pressure, what did you guys use, saw some stuff mentionng a dowel cut to length, or using a solid lifter, or pumping it up w/oil. Maybe low tension springs???

No fear of bending a wrench, and I'm good with the intricacies of a turboprop aircraft engine. Just curious about some of the fine details involved here...how it works type of stuff.

any info appreciated

-Hef

 

[revhead347]

There is a tool that you need to check for pushrod length, if you might think your engine needs different length pushrods. It's basically a pushrod that threads in and and out to adjust length. I have one.......somewhere. Anyway, if you have Edelbrock heads that have not been milled, stock length pushrods are what you need.

Not sure what you are looking for answers to, but I'll do my best. The hydraulic lifter has a spring that holds the plunger to the top, even with no oil pressure. The oil pressure is used to automatically adjust the lifter, so that you don't have to do it mechanically. Keep in mind, most of the time, there is no pressure on the lifter, because the valve is closed. There is a small orifice that oil pressure goes into the lifter. The oil pressure keeps the pushrod tight. When the cam turns over, and the pressure is put on the lifter, the oil is retained inside the lifter for the duration of the valve opening, because there is too little time for the oil to get pushed back out of that tiny little orifice. Keep in mind, we are talking about fractions of a second here. As long as the rockers are adjusted so that the plunger inside the lifter is never bottomed out, or topped out, you are fine.

Adjusting your rockers is simple. With hydraulic lifters, all you have to do is preload them. With solid lifters, you actually have to set the lash, which is quite a bit of work. Here is how you do it. Loosen the polylock to the point where it obviously won't interfere with the movement of the rocker nut. You have to make sure the cam is is the valve closed position for the particular valve you are working on. You will need to hook up a ratchet to your crank nut, so that you can turn the engine over to adjust individual valves. Leave the spark plugs out, to make it easier to turn the engine. When the exhaust valve starts to open, you know the intake valve is fully closed. When the intake valve starts to close, you know the exhaust valve has fully closed. With one hand turn, the pushrod in circles, and with the other hand, slowly tighten down the rocker nut. When you can no longer easily turn the pushrod with your fingers, it means you have no more open slack between the rocker, the pushrod, and the lifter. Then give the rocker nut one half turn to preload the lifter. This will bring the plunger down in the lifter within it's automatic adjustment range. Now lock the polylock while you are holding the rocker nut. Once you have snugged the poly lock, crank the rocker nut nice and tight. Those polylocks don't lock very well on their own, and the rocker nut has a tendancy to back off if you don't do this.

Kurt