Valve Adjustment Question

[JasinC19]

I noticed that when adjusting valves, some of the adjuster nuts would offer resistance when doing the half turn past 0 lash. Others offered no resistance.

Before doing the procedure, I made sure to loosen all the rocker arms and let them sit overnight to let the lifters return to their most expanded state.

What could cause this to happen?

 

[dcurtis]

you need to do them in order with the firing order, start with number 1 on compression stroke, and then just follow the firing order rotating the crankshaft 90 degrees for each.

 

[JasinC19]

Hi Curtis, that is the procedure I was following. If a lifter was defective, and not pumping up I guess that valve would never fully open...

 

[jrichker]

Michael Yount’s valve adjustment procedure

Here's an easy way to determine this. Start with the #1 cylinder. Rotate the engine with a ratchet on the crank bolt clockwise. Watch the #1 pushrods. First the exhaust pushrod will rise and fall signaling what would be the exhaust valve opening and closing if the rocker were on. As it closes the intake pushrod will rise -- keep rotating clockwise until the intake pushrod falls and is level with the exhaust pushrod - both at the same height. Both lifters are now on the base circle of the cam - both valves would be closed if the rockers were on.

Now, install both rockers. Tighten the bolts with one hand while rocking the rocker with the other hand - continue until you reach the point where you can't 'rock' the rocker any more because there's no gap on the valve stem end or the pushrod end. You are at zero lash - i.e. - no gaps. Stop tightening just as you reach this point.

Now, put your torque wrench on the bolt and tighten it to 18-20 ft-lbs while counting the number of turns it takes to reach the torque. You should hit the torque within 1/4 to 1 turn of the bolt. If it takes more than 1 turn, use a shim to raise the rocker -- each .030" shim will reduce the number of turns to torque by about 1/4 turn. If you reach the torque in less than a 1/4 turn, or you have trouble reaching zero lash even at full torque, then you'll either need longer pushrods, or to CAREFULLY remove some material from the bottom of the rocker fulcrum. Using the procedure described above, you will work through the remaining 7 pairs of rockers. If you follow the firing order, it will minimize the manual cranking you have to do to get the lifters on the base circle of the cam prior to installation of the next pair.

When I first went through mine, 13 of them took no shims; 3 of them took 1 .030" shim. Upon cranking it up, one or two of them sounded a bit noisier than I thought was right, so with the engine hot, I pulled the upper off, and the valve covers, and went through the installation procedure again. That time, 11 of them took no shims; 4 of them took one .030", and one of them took one .060" shim. And they were very quiet running.

Good luck with it.
__________________
Michael Yount - K'ville,TN 82 Volvo 242w/5.0L; 2000 Suzuki Bandit 1200

 

[jsw81]

^That is for pedestal mount rockers. I believe the OP has stud mount.

 

[JasinC19]

Yeah I do have stud mount. And I mainly was concerned that some of my lifters weren't working right. If you loosen all rockers, shouldn't all of the lifters bleed down?

 

[txstang84]

What makes you concerned that your lifters aren't working correctly? Does the engine lack power? Run unevenly? Do you have rocker noise?

Lifters bleed down over time, or if the check ball/disc is loose or faulty, or the lifter is made poorly or worn out.

 

[JasinC19]

Hi tx,

This is a new build, and I haven't really been able to get it running smoothly. So I wanted to reset the valve lash to eliminate that possibility.

I set #1 TDC and loosened all rockers and let it sit overnight. When I adjusted them, some were pumped up, a few weren't.

I was wondering why some bled down and others didn't. None of them had load on them.

 

[Hawkeye_306]

The return spring is only partially responsible for extending the lifter, engine oil pressure also acts to extend the lifter during operation.

Normal stiction within a good lifter can catch it & keep it from extending just under the force of the return spring (loosened rockers w/ engine off). Also, if a few lifters have more oil within them than others (e.g., the non-compressed lifters at the time the engine was turned off), the force required to squeeze out the extra oil can make certain ones feel stiffer. You notice the oil resistance effect if you run the engine (fill the lifters), then re-adjust them a few times w/o running the engine again & they feel looser the second time through.