Thread: Quick Valve Lash Question

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First the procedure:

The cam in my ZZ430 clone is 218/228 @ 0.050, .525/.525 lift, 112 LS.

I originally set the valve lash by going to TDC on each cylinder, then 1/2 turn past zero lash.

I've always done it that way, and never had problems. But because of some discussions on this board, and the cam grinders instructions I've read lately, I decided to re-run the valves as follows:

When the exhust valve starts to open, I set the intake.
I then ran the intake to full lift and back down until it was about to close, and set the exhaust.

Now the question:

On some of the valves, the half turn is very easy, and, right after adjustment, I can push the rocker down with my thumb. On others, the half turn is quite stiff, and I can't move the rocker with my thumb at all. Does this sound odd?

Hi henry, i set my valves the same exact way you described and i feel that some of mine are to tight also , but i don't know why either, i was told that it has to be because i was not perfectly on the bottom of some of the cam lobes.

Originally Posted by Henry Rifle

First the procedure:

The cam in my ZZ430 clone is 218/228 @ 0.050, .525/.525 lift, 112 LS.

I originally set the valve lash by going to TDC on each cylinder, then 1/2 turn past zero lash.

I've always done it that way, and never had problems. But because of some discussions on this board, and the cam grinders instructions I've read lately, I decided to re-run the valves as follows:

When the exhust valve starts to open, I set the intake.
I then ran the intake to full lift and back down until it was about to close, and set the exhaust.

Now the question:

On some of the valves, the half turn is very easy, and, right after adjustment, I can push the rocker down with my thumb. On others, the half turn is quite stiff, and I can't move the rocker with my thumb at all. Does this sound odd?

It sounds to me like some of your rockers are "pumped-up" and some are not??

were the valves adjusted with the lifters dry or were they presoaked?

Dean,

I've driven the car almost 100 mi, so I'm pretty sure they're soaked.

Eric,

That's what I'm thinking, since I drove about 15 miles today. I adjusted them a couple of hours after I parked it - just enough for the engine to cool to the touch. The way I adjusted them just has to be correct. It's a couple of hours later now, and I can move some of them that I couldn't move before.

I just cross-checked with every cylinder at TDC, and it all looks good. The only lifters that are tight now are in #8, and I double-checked them at 1/2 turn.

Looks good to go.

The reson i ask is some lifter companies tell you to do the adjustment with the lifters dry because some times if the lifter is soaked some of them may be full and when you go to adjust you are actualy pushing down on the valve instead of the lifter plunger,
I hope i explained that correctly. may be this will help ya...

Dean

i pulled this straight from crane cams web page.

Many people mistakenly believe that hydraulic lifters must be soaked in oil overnight and be hand pumped up with a pushrod before installing into a new engine, however this is not necessary. In fact, this could cause the lifter to act as a "solid" and prevent obtaining proper preload.

1. Hand rotate the engine in its normal direction of rotation 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. (Why? Because when the exhaust valve is just beginning to open, the intake lifter will be on the base circle of the lobe, the correct position for adjusting the intake.)
2. Back off the intake rocker arm adjuster and remove any tension from the pushrod. Wait a minute or two for that hydraulic lifter to return to a neutral position. The spring inside the lifter will move the pushrod seat up against the retaining lock if you give it time to do so. (If you are installing brand new lifters they will be in the neutral position when they come in the box.)
3. Now spin the intake pushrod with your fingers while tightening down the rocker arm. When you feel a slight resistance to the turning of the pushrod, you are at "Zero Lash". Turn the adjusting nut down one half to one full turn from that point. Lock the adjuster into position. The intake is now adjusted properly.
4. Continue to hand turn the engine, watching that same intake. 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. (Again, when we see the intake almost closed, we are sure that exhaust lifter is on the base circle of the lobe.) Loosen the exhaust rocker arm and follow the same procedure described before in steps 3 and 4 to adjust this rocker arm.
5. Both valves on this cylinder are now adjusted, and you can move on to your next cylinder and follow the same procedure again.

Originally Posted by DennyW

I don't like to spin the push rod, and the reason is, you may not get the right feel.

I like to (move), or ((jiggle)) the rocker up and down while snugging up the adjusting nut to get to Zero lash. You can feel it much better, when all the play is out, and there is no error about getting to the 0 lash.

Denny,

That's exactly what I do. I never could get the feel by spinning the pushrod.

Rotating the push rod is affected by the lubricant; sometimes the lubricant on your fingers! Both ways work, you should use the method that works best for you.

The Intake Closes-Set the Exhaust and Exhaust Opens- Set the Intake method gets the lifter on the heel of the cam lobe. It is certainly a good way to adjust.

FYI, for a 3/8-24 stud thread, each 1/2 turn of the rocker arm nut moves the rocker arm down appx 0.021" times the arm ratio = about 0.035" for a 1.5 arm.... if my head is working right today.

mike in tucson

Originally Posted by DennyW

Your first part, may work for some, and that's ok. But, if you want to be exact, and that means weather the lifters are full of oil, or, if you are doing this on a build, with no oil in the lifter, the up and down checking of play, is more acurate, especially for a newbe doing this for the first time.

Also, on a pretty stock Chevy motor, if you have 1/4" of thread showing above the stock style adjusting nut, that is right at the proper adjustment.

ps: I wanted to add to this. If you have 5 people standing around, and you have a 0-1" micrometer. A .0500 pc of round stock. Ask each one to measure it without using the ratchet type torque built into the mic. You will find that the feel is different for each person when they measure the pc of round stock.

what your saying is denny very true. you could here this i told you what size it was hang on i will show you you just give it a bit more of a turn now were did you put the vise grips funny but not to far off this happen to a friend of mine .there is only two guys that i would let use my mics or and thing i use to measure parts with

Hi Henry and the others!

I haven't quite understood what your problem is: Do the adjusting nuts feel tight or do the lifters themselves feel tight? I presume you mean the second one, because the first is absolutely normal with those selflocking nuts, some of them are just harder to turn than others.
Your lifters are full of oil. That means they are full of oil to the point where you last set the lash at. So when you last set the lash on that engine you turned the nuts down to zero, then plus a half turn. That means your lifters where now never at their full length again, because the pushrod keeps them slighty depressed. Now if you let the engine cool down, the lifters will bleed down a bit further than they where already because you have set them in the past. Now if you set them at this stage, the depression from before will feel like zero lash. So now if you go plus a half turn you'll already be one whole turn down. Make a mistake in the setting before and you'll double it now.
Lifters have a small valve in them with a spring, to keep the oil pressure up. When the pressure outside the lifter sinks (like when the engine is off) a little oil flows out of the lifter through this valve (bleed down). As the valve itself consists of a little round ball which seats in a hole a speck of dirt could be holding it closed. That would mean that that lifter would stay "solid" when the others have bled down. That isn't a problem, because during operation the pressure in the lifters is high and it would act normally.
If you have set the lifters correctly they should feel completely stiff as soon as you give them the half turn. Wait for a couple of minutes and check the lifter again and you should be able to wriggle the lifter easily. If that is not the case try setting the lash with the engine running. When the engine is running the lifters will "grow" to their full height once the pressure from the pushrod is removed. Do one Cylinder at a time and just losen it far enough to hear a constant klicking sound. Here you have the bleed-down phenomenon again: As soon as you back the srew up slightly you will hear a faint klicking sound which will get fainter til it's finally gone. That is because the lifter takes a time to pump up, and when it's pumped up to meet your pushrod you'll be at zero lash. Only when the klicking doesn't stop anymore you can turn off the engine and set that valve they way you described. You can only do it then perfectly, because the lifter is then at its full height, and all engine componants are warm, which they should be for setting the lash.
It's ever so easy to bottom out a lifter if you reset the lash too often... That would hold a valve open at the least.

Was this confusing

Max

Max,

No, it's not confusing. I have the Chevy version of Poly-locks - with a setscrew. They turn very easily.

If I turn the nut down lightly with my fingers, I can feel when it contacts the piston in the lifter, and the pushrod has no more slack. I turn it a half-turn and lock it. The half turn is very easy, and does not feel firm at all. I can then push on the rocker with my thumb, and feel the piston in the lifter move, so I assume that the original setting (before the half turn) was at zero lash.

If I back off the rocker and let it sit for a couple of minutes, won't the lifter piston return to full extension?

I must be having a senior moment. I've only had one solid cam in my life, and have adjusted hydraulic lifters a thousand times. Maybe I'm over-analyzing.

Here's what I ended up doing:

• Pulled all the plugs.
• Removed all of the poly-locks and rockers
• Spun the engine with the starter until the oil pressure hit about 40 psi, which pumped up all the lifters.
• Put all the rockers back on without the poly locks.
• exhaust start to open/adjust intake, intake almost closed/adjust exhaust, install poly-lock, turn about 1/2 turn, tighten set screw, turn poly lock a bit more to lock in place.
• repeat 7 more times.

Worked fine.

Well I am not quite confused but amazed that there is so much variation among experienced folks, but I think Denny put his finger on the problem and that is why hydraulic lifters were invented, to make up for variation in manual settings. However you guys do have me sufficiently confused on this that assuming my dry settings allow the engine to run at first I am going to rely on resetting them while running with a slotted valve cover. With solid lifters in a VW engine the lash could be set tight if you were careful and gain 2 or 3 HP which is quite a bit if the engine is rated at 50 HP but with hydraulic lifters the oil pressure is supposed to regulate the lash AND absorb variation in the settings for different cylinders. Maybe that is why ol' Henry ground the valve lash at the factory and you did not have to worry about it unless you put in Johnson adjustable lifters. Hey, I am just listening and learning.

Don Shillady
Retired Scientist/teen rodder

Don,

I haven't set hydraulics with the motor running for at least 30 years. The method I used above is the one recommended by all the cam companies, and it was in the instructions that came with my GMPP cam. You can easily set hydraulics with the motor off, and you'll never have to touch them again. (although that may not be obvious from several of my early posts on this thread) I just had a moment or two of temporary insanity.