Rocker arm adjustment procedure

[QWKSNKE]

From my 'Edgar' notes.

If this a stud mount rockers this is what you do. Turn the motor slowly until you see the exhaust valve to start opening, stop, go to the intake valve tight it until there is no lash, then go 1/4 of a turn then lock the poly lock. Now turn the motor again, now you are going to see that the exhaust opens completely and then the intake starts to open, now let the intake valve open completely but as soon you see it to start closing, stop, now go to your exhaust valve do the same thing as the intake, then do all of them like that and you are set.


Edgar

[Sendero]

You wanting me to FAQ this?

[QWKSNKE]

not yet

[coupe]

Basically, make sure the pushrod is on the base-circle of the cam...not the lobe.
When the pushrod is about to push in the lifter spring (or when you cannot turn pushrod by hand anymore), you're at zero-preload on the lifter...stop and give about 1/2 turn more (or around .020"). Tighten the lock-nut & then put a little-more snug on the rocker nut again...This assures the locknut is in tension on the stud...will not back off.

[svopaul]

Basically, make sure the pushrod is on the base-circle of the cam...not the lobe.
When the pushrod is about to push in the lifter spring (or when you cannot turn pushrod by hand anymore), you're at zero-preload on the lifter...stop and give about 1/2 turn more (or around .020"). Tighten the lock-nut & then put a little-more snug on the rocker nut again...This assures the locknut is in tension on the stud...will not back off.

Actually it's not "when you can't turn the pushrod by hand anymore" that is too tight. You tighten it up until the pushrod starts to give resistance to spinning...if it stops completely and you can't sping it then it's too tight. Then it's 3/4 turn past Zero preload ;)

[coupe]

Actually it's not "when you can't turn the pushrod by hand anymore" that is too tight. You tighten it up until the pushrod starts to give resistance to spinning...if it stops completely and you can't sping it then it's too tight. Then it's 3/4 turn past Zero preload ;)
No, you're right. The preload really has nothing to do with how tight the pushrod "feels." because if you try your method with a new, non-pumped lifter, it will tighten freely until it bottoms out. That's why it's critical to just have the pushrod against the spring in the lifter. Then it's at zero preload...but it takes a fine-touch.

I also am leery of the 1/4 up to a full turn I hear people talk of. I've tried both & it's noisy on some rockers, quiet on others. I've found a good balance at around .020-.030 in which case you should measure the thread pitch to find true preload. Just clarifying...Good thread. ;)

[QWKSNKE]

Using Edgar's method you will not be able to rotate the pushrod when everything is tightened down.

[svopaul]

Right...once done and adjusted you should not be able to rotate any of the pushrods.

[Wickd GT]

Right...once done and adjusted you should not be able to rotate any of the pushrods.


Once the adjustments are done, you will fine some lifters a bit loose because they have not been pumped up, once the motor has been fire up and the lifters pumped up you can not turn the push rods. My motor they way I set up my rockesr is like I said, once the push rod touches the lifter and the rocker arm and the slack between the rocker arm and the pushrod is taken away then I give it 1/2 a turn. But when I want it to rev up the moon, I give it a 1/4 of a turn.


Edgar

[coupe]

That's right. The "preload" is nothing more than a "float-cushion" for the valve as it crests the lobe of the cam. A solid will be noisy if not adjusted perfect...the hydraulic has a little leeway...a bit loser for high-revs. But there's really quite a bit of tolerance in the adjustment of hydraulic rockers...it's meant that way for even idiots to handle. That's why I feel like an idiot. :(

[1sicklx]

Instructions in easy to follow format:


Remove the valve covers, and pick a cylinder you are going to set the pre-load on. Only do one cylinder at a time.
Rotate the engine in its normal direction of rotation (clockwise) and watch the exhaust valve on that particular cylinder. When the exhaust valve begins to open, stop and adjust that cylinder's intake rocker arm.
To adjust, back off the intake rocker arm adjusting nut and remove any tension from the push rod. Wait a minute or two for that hydraulic lifter to return to a neutral position. The spring inside the lifter will move the push rod seat up against the retaining lock, if you give it time to do so.
Twist the intake push rod with your fingers while tightening down the rocker arm. When you feel a slight resistance to the turning of the push rod, you are at "Zero Lash". According to FTI, Turn the adjusting nut down 1/2 to 3/4 of a turn from that point for street applications. Use 1/8 to 1/4 turn for race applications. Lock the poly-lock on the adjusting nut. The intake is now adjusted properly.
Continue to turn the engine, watching that same intake valve/rocker you just set. It will go to full open and then begin to close. When it is almost closed, stop and adjust the exhaust rocker arm on that particular cylinder. Loosen the exhaust rocker arm and follow the same procedure described before in steps 3 and 4 to adjust this rocker arm.
Both valves on this cylinder are now adjusted, and you can move on to your next cylinder and follow the same procedure again.