Future_Z_Owner

So im just getting done rebuilding my engine. This is the first time i have ever done anything like this period. So its been an interesting experience to say the least. Anyways im almost done i need to do my valve adjustments and i was told to do it with the car running. Im finding that the chatter is so loud that i cant really tell the difference with the one im working on. Anyways my car has the LT4 hotcam in it with the GMPP 1.6 rr's. Im a little concerned because im getting this loud noise from under my car.. I was told thats where knock would be the loudest. I have never heard engine knock so i dont know if this is what is going on or not. Please check out this video and let me know what you think.
http://www.youtube.com/watch?v=TkC0_Wr13tE

SPEED#1

IT sounds like the rocker arms but could be something else.

Dave1980

Try the other non running adjustment methods and take your time.

Sk8phreak88

I've found the easiest way is to do it running personally.. What I did was turn the crank manaully to try it and get them set to what "should" be right. Then I started the car and loosened one at a time to chatter and then tightend it down till it was quiet.. Well as quiet as Pro Mags can be!

JAKEJR

By now I shouldn't be, but I'm still continually amazed at how many different ways guys come up with to set their lifter preload.

Jake

West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!!

Dave1980

The important part is you find something that works for you and are consistent with it.

Sk8phreak88

Pretty much.. It doesn't take me long to do it and I know they are set right everytime I do it.. Works for me.

AlwaysCode390

Exhaust leak? ---

JAKEJR

First, for the OP, you're not adjusting your valves, you're setting the correct lifter preload.

Second, I've never read or heard of such an unorthodox method to set the correct lifter preload. Doing it that way, essentially, allows sound to determine the lifter pre-load as opposed to the usually recommended plunger depression of .030"/.040" as being the recommended, correct way.

Goals are crossed: The GOAL in setting lifter preload is to tighten the adjusting nut/poly lock so that the lifter plunger is depressed .030"-.040" The goal is NOT based on sound.

I'd be interested in reading an article from some reputable engine builder, magazine tech article or Service Manual, etc., that says that's the way to do it.

As far as unorthodox methods, I read one post where the guy recommended setting the lifter preload by using a dial indicator!!! Talk about unorthodox.

However, as with so many other things, to each his own. For those who choose to do it that way all I can say is "have at it", but don't delude yourself into thinking it's the correct/recommended procedure.

Jake

West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation DayParde 20 May 2010!!!

siguy

sounds like a rocker arm ... how many miles on the car?

if you adjust them do it while the car is running and hot.... this is the best way .... yes there are other way you can do it while the engine is off ... but i find it best to do it while running if you want a step bu step let me know and i will post how to do it

siguy

With the Chevy lifters there is no way to determine .30-. 40 with you have the intake on etc how in the world would you measure that...? not possible.. (That’s why they say adjust to zero lash then turn ¾ to ½ turn to get the right lifter pre-load…

It best to adjust the valves (pe-load lifters which it the same thing) The best is to do it while hot and have the car running … (a quick run down on how to do it would be to loosen the rocker untill you hear it clicking then tighten it until you just barely here it ticking then turn ½ to ¾ turn to set the correct pre-load) (some after-market lifter require less)

Any high performance car will tell you that unless you are adjusting a mechanical cam... then that’s a different ball game.


Dumb question (and I am not being an *** its a serious question) have you adjusted many valves (lifter preload) your self ?

JAKEJR

[QUOTE=siguy;6173201]
Well, since you asked, first I'm 64 years old and have been screwing on these suckas for well over 40 years.

For many years I built BB Chevy engines for several 1/4 mile racing teams in the Chicago area, all were high to mid 8 second cars in the quarter mile. Each car was very competitive at all the meets they attended, I use to drive a BB roadster that ran mid-8s at over 175 MPH, so, yes, I've turned a wrench a time or two, which would include both adjust valve lash AND lifter preload.

As recently as a few months ago, I pulled the engine from my son's 96 Vette and installed new Dart heads, Scorpion 1.7 RRs and a custom ground CompCams hydraulic roller, which I degreed-in using the Lobe Centerline Method. As a point or reference, I set the lifter preload at 3/4 turn since I've found that setting results in the quietest running valvetrain.

I was always able to maintain my reputation with those teams by paying attention to detail which inspired confidence in me by the cars' owners.

Attention to detail includes use of the correct vocabulary. Not calling a flexplate a flywheel, not saying 'adjusting valves' when, in fact, you'd be adjusting lifter preload on a hydraulic cam, not calling a car's "engine" a motor, buying a set of 'rims' instead of the correct word 'wheels' (a rim being a part of a wheel), etc., etc.

I much prefer that especially younger guys, who are starting out learning about our engines, be exposed to the correct termonology and word usage so as not to spread inaccurate information. Just a matter of being accurate and precise.

I'll attached a file in a different respnse, I created several years ago that I send to younger guys who aren't up to speed on setting lifter preload. It's also posted as a STICKY on several other Forums. I constantly receive PMs and emails from guys thanking me for explaining what too few have actually been able to before.

When a guy posts asking for the procedure, usually what he receives as a response is a couple of lines, maybe even a paragraph or two, which leaves the original poster not much more knowledgable than before he originally posted. In my directions, I attempted to explain not only 'what' to do, but also "why'.

Jake

West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!!

JAKEJR

Here are the directions I share with others:

For your reading pleasure:

First off let me say that there are several different ways to set lifter preload and all of them will work, but only if done correctly. It seems that each recommended method is the author's preference, so I'm not saying that any of them is "wrong" or "bad", it's just that one method is less error prone than the others. That being the main difference among the various methods.

Doing it the way shown in many manuals makes it really easy to mis-identify one of them (you'll adjust an intake when you should have adjusted an exhaust, etc.) Only after the engine is started will you find that you'd made a mistake, then it becomes the task of finding out which one was set wrong.

Others prefer the adjust preload while the engine is idling method, which is pretty "old school" and can easily cause an engine fire. Ask me how I know. Even if you don't get a fire from the hot oil falling on the exhaust, it can be a messy procedure.

The least error prone method is the one I'm writing about now. The IC/EO method. Okay, here's the procedure:

The goal is to adjust the rocker arm adjusting nut enough so that it depresses the pushrod and thus the lifter plunger .030"/.040". Since it would be very difficult to actually measure that amount - requiring a dial indicator with a magnetic base, etc., turning the adjusting nut a certain amount will work just fine.

A word of Caution: If the engine has been run before using this procedure you'll need to loosen all the rocker nuts to relieve any pressure on the lifters and wait about a minute.

This gives the lifter plungers time to travel back to the top of the lifter and not be depressed. If you fail to do this you could have a false ZERO lash position which will effect the correct preload.

More on ZERO lash will follow.

Most importantly, in order for the lifter preload to be set
correctly, the lifter HAS TO BE on the base circle/heel of its
camshaft lobe. This warranted repeating.

Since there's no practical way to actually SEE if the lifter is on the base circle/heel, you simply watch what its companion pushrod does in order to know. You watch the intake to set the exhaust, then watch the exhaust to set the intake.

By watching what the INTAKE is doing you can determine
what the EXHAUST is doing and vice versa.

May sound crazy but that's how it's done.

To begin, install all the pushrods in their respective lifter and
set the rockers and adjusting nuts loosely in place. Then you'll
need a way to turn the engine in it's normal direction of rotation.

I sometimes use a ratchet, extension and socket on the damper nut. Having the spark plugs removed will make the engine much easier to turn too, but it's not essential. On occasion I've used the engine starter and ignition key to bump over the engine and on others I've use a hand-held bump starter connected to the starter solenoid.

If you're not familiar with it, a bump starter is a hand-held device, looking something like a joystick with a "fire" button. It has two wires which connect to the starter solenoid. Each time the "trigger" is momentarily depressed, the engine will bump over. If the trigger is held, the engine will crank non-stop.


Start at the driver's side, front, very first rocker, which will be
the #1 EXHAUST. We'll be setting that one first.

Grab the pushrod of next to it, which will be the #1 INTAKE pushrod, with your thumb and index finger so that the pushrod can be moved UP and DOWN.

Turn over the engine while feeling what the #1 INTAKE pushrod is doing. That pushrod will, at some point, begin to move up (indicating the INTAKE valve is beginning to open) reach it's maximum lift point and then begin to move down. Just before that pushrod is all the way back down, STOP turning the engine. The actual point that you STOP isn't all that critical, just as long as the pushrod has moved more than half way back down.

With the #1 INTAKE pushrod in that position, the #1 EXHAUST lifter will be on the base circle of its lobe.

Now, (back to the INTAKE pushrod being almost all the way back down) - move your hand to the #1 EXHAUST pushrod and begin to gently move it up and down with your finger/thumb while at the same time begin to tighten the #1 EXHAUST adjusting nut/poly-lock.

When you reach the point that the EXHAUST pushrod can no longer be moved up or down you've found what we call ZERO LASH. ZERO PRELOAD is probably a more accurate name for it, but ZERO LASH is what it's usually referred to.

Some directions would have you twist the pushrod until slight resistance is felt - yes, SLIGHT resistance is what's recommended not tight resistance. However, what's SLIGHT to one person isn't to another. So DON'T USE the twist method; again, it's too error prone.

It's now time to set the lifter PRELOAD on the #1 EXHAUST lifter. Most use 1/2 turn of PRELOAD, so turn the adjusting nut 1/2 turn more from ZERO LASH results in the desired preload of .030/.040" of lifter plunger depression. Remember, that's what we're after, pre-loading the lifter plunger .030"/.040".

1/2 turn is what is usually found as the recommended amount to turn, but some guys prefer 1/4 turn and still others, (like me) prefer 3/4 turn. Some even go with one full turn, which is what I believe is found in the manuals. In my case, I find 3/4 turn results in a quieter running valve train, with no downside since I seldom carry my engine above 6 grand. The amount of preload you select is pretty much a personal preference thing, so you can deviate from the 1/2 turn setting if you choose to.

Less preload, like 1/4 turn, is touted as allowing a few hundred more RPMs before lifter pump up, which is the main reason some choose it. However, that loose a setting can result in

Damage can occur if the clip which holds the internals of the lifter in place bangs against the top of the lifter body. The clip can break and so will the lifter and maybe your engine. I don't recommend 1/4 turn or less of preload on stock-type lifters. At least one brand of lifter DOES REQUIRE such a small amount of pre-load, so if you're running those, follow the directions for those type lifters.


In the remainder of these directions, I'll use the 1/2 turn recommendation since I find it to be the most often recommended setting. 1/2 turn equals the handle of wrench at, say, 12 o'clock, then turn the wrench until the handle points at 6 o'clock. That's 1/2 turn.

If you're using Poly-locks, once that 1/2 turn is made, tighten
the Allen head set screw with your Allen wrench. Make sure it's tight! More on this "tight" later.

That one's done.

Now we move on to setting the #1 INTAKE.

To set the INTAKE, we grab the #1 EXHAUST pushrod (the one we just finished setting) with those same two little fingers - or you can just watch what the rocker is doing - either way works.

Begin, again, to turn the engine over manually while watching the #1 EXHAUST rocker or feeling its pushrod. AS SOON as you see the #1 EXHAUST rocker begins to open that valve (or feel the #1 EXHAUST pushrod begin to move UP), STOP. You just found the point that the #1 INTAKE lifter is on the base circle of its lobe.

Now grab the #1 INTAKE pushrod with your index finger and thumb and begin to gently move that pushrod up and down as you slowly tighten its adjusting nut.

When that pushrod can no longer be moved up or down you've just found ZERO LASH for the #1 INTAKE.

Again, tighten the adjusting nut an additional 1/2 turn to set
the .030"/.040" preload and tighten the Allen head set screw, TIGHT.

The #1 INTAKE and #1 EXHAUST are now set.

Now move on to the very next pair, #3s and do the same thing. Continue working down the line to #5 then #7.

Once those are done move to the other side of the engine and begin at the very first, front rocker/pushrod (#2) and repeat, going straight down the line (4,6 and finally 8). After you're finished with #8 EXHAUST, you're done setting the lifter preload.

If you just do one after the other, straight down the line, you
won't mistakenly skip any and each will be set properly.

Now, there's one last step: Grab your box end wrench and give each nut (poly-lock) a good tightening turn to make absolutely sure the set screw (the screws you tightened with the Allen wrench) are really tight. This will prevent any loosening over time. There's no torque spec (none that I know of) for this last tightening, so you have to do it by "feel". Once you begin tightening, you'll be able to feel when it's REALLY tight. Just don't CRANK on the nut like a gorilla (LOL) or the nut(s) can crack/split.

JUST REMEMBER: On the L98-LT1/4 engine the valve arrangement is EIIEEIIE with E=EXHAUST and I=INTAKE It's extremely important to know which valve you're working on, an INTAKE or an EXHAUST. Other Chevy engines may have a different valve arrangement, but the procedure is the same.

After you've tried all the other competing methods and have finished pulling out your hair, do it this way and be done with it.

Hope this helps

Jake

West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!!

dirtybird81

adjusting with the car running used to be the preferred method at the dealership
gm even produced a tool to deflect the oil away from the exhaust. like jake said though if youve got an expensive set up with after market cam ,lifters, rockers etc. better take the time to do it slow after all it would suck to round a lobe off of that shiny new cam.

siguy

adjusting the valves is not as complicated as many of you are making this out to be.. yes true the correct term is setting the lifter pre-load...