Birdstheword

so ,the 1988 service manual says to positon #1 cyllinder TDC blah blah blah , reach the point of zero lash . THEN tighten rocker arm nut 1 and 1/4 turns install valve cover and start engine to adjust idle speed . THATS IT ? is this correct ? i've been told by others on this board that this procedure is better done with the engine running and half turn pre-load "while others say 3/4 turn " im confused and i dont want to bend any valves .

chesterfield

read this and make your own call

http://www.corvette-restoration.com/...Valve_Lash.pdf

Apeiron

The service manual's 1 1/4 turns is for new lifters on new cam lobes. By the time it's broken in, it'll be a bit less.

Birdstheword

does that apply to roller lifter type?

Apeiron

Not so much, but the pdf that chesterfield linked covers it all pretty well.

mlynch001

The GM procedure is right on, but others can be used as well. The procedure that Chesterfield refers to is excellent as well. The "blah,blah,blah" in the shop manual is all the details between #1 and #2 in the firing order. Many people used to ZERO LASH their hydraulic cams to get more RPM from their cam. I have used 1/2 turn for years and my roller cam is set at 1/2 turn from zero lash and is silent. I would NOT set the lash running! Too messy and too easy to make a mistake. The static adjustment is by far the best way to do it. That way each valve is set the same. My 2 cents!

JakeJr

There are a few competing methods to set lifter preload. Seems that each advocate has his/her own preferred way to do it. In fact, all of them will work, but only if done correctly - and there-in lies the rub - as they say.

Adjusting the preload while the engine in idling is pretty "old school" that seems to have hung around for decades. I recall doing it that way four decades ago. Lately, though, the recommended method has changed and now most literature recommends the preload be set with the engine NOT RUNNING.

Even the NOT RUNNING recommendation has at least two different ways. One involves what is normally found in shop manuals and which calls for the person making the adjustments to move from one side of the engine to the other. Another NOT RUNNING method - and the one I recommend - calls for the person making the adjustments to merely start with the very first lifter and work backward toward the firewall and then switch sides.

Remember, though, all of them will work but only if done correctly.

The most critical part is to make absolutely sure the lifter is riding on the base circle/heel of the camshaft lobe when ZERO lash is found and the preload is set. If the lifter is riding on the cam lobe's ramp, then everything else that follows will be wrong.

As far as how much preload to use, that's all over the map too. I've seen guys recommend so little preload that I wonder what's going on between their ears. Even though Crane and others warn that too little preload can result in valvetrain damage, these few guys continue to advocate less than 1/4 turn of preload. Too little preload most often results in a noisy valvetrain also.

Most manuals will recommend ONE FULL TURN (+/- 1/4 TURN) - which means anything between 3/4 TURN and 1-1/4 TURN is within spec. So a guy using 3/4 TURN of preload is just as correct as another guy using 1-1/4 TURN.

Those recommendations are usually for stock, GM lifters though. Since there seems to always be so much confusion surrounding preload, I follow the recommendation of the company that manufactures the lifters. If the company says 1/2 TURN, that's what I do.

I recommend you concentrate your efforts on correctly finding ZERO lash since it's the most important. To help relative "newbies" I prepared and posted as a STICKY a step-by-step procedure; it's posted on several Forums.

Jake

bluers91

This can be though to figure out the first time since you hear of so many methods. When I first tried this on a 454 with a new Crane cam and lifters I followed the book, went in the order they specified, tried to find zero lash, then go 3/4 turn and it didn't quite workout for me! The engine wouldn't start since they were set too tight and there was NO COMPRESSION. I was dumbfounded and spoke with a few more experienced people. I ended up backing them off until the rocker was just at zero lash or even slightly loose and got it to start. Ended up doing the adjustment the dirty way with it running and oil squirting all over. It was painful and messy, but it worked and in the end I was happy with the results. Until the lifters have fully loaded up its really hard to tell where you stand with hydraulic lifters. All this 1/4, 3/4, 1 full turn stuff can be somewhat misleading depending on the situation.

JakeJr

Which is exactly the reason I continue to repeat if "DONE CORRECTLY". Forums, like this one, are LOADED with posts from posters who've done something incorrectly. Human nature, being what it is, causes many of them to get defensive when they're told they did it wrong. Many simply can't accept the fact they did something wrong and, instead of admitting whatever they did was done incorrectly, they make up excuses.

Choose which-ever method that floats your boat and follow the directions for THAT SPECIFIC METHOD, without deviation. Don't mix one method with another. The method someone chooses is basically a personal preference thing anyway since all of them will work if DONE CORRECTLY.

For me, it's just that one method is easier than the others, so it's the one I use. Other guys may find a different method easier, so they go with that one. A couple of methods are more complicated and more prone to result in an error but they'll work just as well if DONE CORRECTLY.

Some of it has to do with the amount of Grey matter between the guy's ears, too. Some have a hard time remembering which end of the spark plug goes in the hole.

All of the procedures usually found in manuals, on websites, etc., will work fine IF DONE CORRECTLY. There are a whole host of things that will make things go wrong - INCORRECT - though- adjusting an Intake when it should be the Exhaust that gets the adjustment, adjusting preload with the lifter on the lobe's ramp instead of it's base circle, etc.

Reading comprehension and the ability to follow directions are probably the two main things that trip up guys. That applies to everything, even something as (seemingly) simple as changing spark plugs. One has to be able to understand what he's reading. It's amazing how many can't and don't. Anything over one paragraph in length and their eyes glaze over.

All the different procedures will work if DONE CORRECTLY.

Younger guys are particularly susceptible to making mistakes. Generally, they tend to work too fast, don't concentrate, lack the ability to pay Attention To Detail, aren't precise. Good thing is that as they mature they'll get better. Younger guys are easier to teach though, since their minds haven't been poisoned with a lot of incorrect foolishness.

Also, it doesn't matter if the lifters are filled with oil or not. In fact, CompCams specifically discourages that, saying NOT to pump up the lifters with oil. Yet guys still insist on doing it. As long as the lifter is riding on the cam's base circle, the absence or presence of oil in the lifters makes no difference.

Now I'll get someone to post that he did such and such and had a negative result - however the actual reason it didn't work out well is what he did wasn't DONE CORRECTLY. Made a mistake then blamed it on something else.

By far, the easiest way is to have a mentor. Some Grey-beard who's been working on engines since the beginning of time and who will walk the newbie through the method - step by step. Once it's "learned" a light-bulb will come on and it'll seem SUPER SIMPLE.

Choose your sources very carefully!!! Many on Forums like this one are on ego trips - they JUST HAVE TO BE RIGHT. They can muddy the water so badly the reader will find it really difficult to distinguish right from wrong. As a result confusion increases. I could name names, but all that would do is start a BIG argument. Over time they'll become known though.

When I typed up the preload STICKY, like the one I posted on LS1LT1.COM, I wrote it with the Newbie in mind. (Write to your audience). I tried using terms that wouldn't confuse and I explained not only WHAT to do but, also WHY. I tried addressing the questions that a Newbie would normally have. No, I didn't get to all of them, but I tried. The STICKY is long, so those who have an aversion to reading are going to have a rough time.

LEARN TO LOVE TO READ. READING IS FUNDAMENTAL!

Just m thoughts.

Jake

Birdstheword

Thanks for all the input guys , anyways , I did the one cyllinder at a time method " watch theintake valve close then line up balancer notch @ 0* " and i did a 1/2 turn preload and i got oil all over the place and really noisy valvetrain , so i went back to square one and whent by "the book " #1 @ TDC adjusted 1 2 8 etc etc . then rotated the crank 360* and did the rest " what ever the booksaid " . BTW the second time i gave it 3/4 turn for preload and i got way less oil splash " almost none " and only one valve was ticking , the rest were quiet . so now since i have the valves preloaded . should i loosen the valve until it ticks then tighten it until its quiet the 3/4 turn ?

dimented24x7

iTrader: (2)

The proper way to adjust the valves is to go to each cylinder, and observe the intake and exhaust valves. Rotate the engine in the normal direction. When the exhaust valve just begins to open, the intake valve lash can be adjusted. When the intake just closes, the exhaust valve lash can be adjusted. This ensures that each of the lobes on the valve being adjusted is on the base circle. This works for all cams. Repeat for each set of valves.

Also, the proper pre-load is one full turn. Ive found the hard way that some types of lifters will not work properly with less.

Apeiron

With stockish lifters, but there are plenty of performance lifters that won't with with that much, too.

djmarch

iTrader: (4)

Interesting threads gents...I just installed a set of sbc steel roller rockers on my 350 and their procedure was 0 preload. Tighten jam nut untill push rod can be barely turned by fingers..Maybe I should go back and give them a 1/2 turn....

Apeiron

Rockers don't have a procedure for preload, lifters do. You need to go back and set them.

Tafsky86

Okay guys here's what I was taught by a GM tech at a Chevy dealer I worked for... Please tell me what you think abou thtis procedure. Whether it's good, bad, or ugly. If I am doing something wrong and what not.

Example: I am going to install a set of stamped roller rockers in my 305 V8 TPI.

Take off valve covers. Remove old rockers. Install new roller rocker on stud (AFTER having soaked them in oil for a day or so). Then screw the nut onto the the stud 15 turns clockwise (maybe it's twelve, sorry for the error if I'm wrong). Start the engine. Motor will run a little rough, that's okay. IF you are lucky enough to have these little metal shields that clip onto the pushrod to prevent oil from squirting all over, put them on. It still will be a little messy though so I'm not sure if this really matters. Start at Cylinder #1 back off nut till it starts to tick. Then turn, in quarter incriments to be safe, until it stops ticking. Then give it one more quart turn to half turn. Repeat procedure for all rocker arms to adjust valves.

What do you think guys?

One more question. I did that for the first time on my IROCZ... I still have a bit of a tic and I can hear right where it is. Do I need to start from scratch AND adjust all of them OR can I adjust the ones I think it is?

Apeiron

Screwing the nut down an arbitrary number of turns to start is a terrible way to do it. Depending on the length of the stud, thickness of the rockers, cam base circle, deck height, etc., 15 turns can easily be too little or too much.

If yours are making noise, you can adjust just those ones or all of them, and you can do it with the engine running or stopped. Up to you.

Drew

iTrader: (58)

This thread is going to confuse more people then it ever helps. There are just too many different schools of thought, and too many people posting that really don't know what they're doing.

Apeiron

I think it's more that everyone seems to regard it as some sort of magical process, rather than a desired end-state.

FSTFBDY

iTrader: (33)

to many diff. ways to do it. Try a few, see what your conferrable/ easy doing.
If they are right in the end thats all that matters.

That being said all the above are right also.. Here are a few listed out for future readers. Ive used these ways with good results.

TDC
I hold the pushrod between two fingers lifting the pushrod up and down while slowly tightening. When you reach the point where there is no up and down movement you will be at ‘0’ lash. Then I go 3/4 turn.

The problem with spinning the pushrod and attempting to get the correct ‘feel’ is that you can and will still be able to spin the pushrod even if you bottom out the lifter. This can cause you to over tighten the adjustment and can lead to bent and / or broken pushrods and valves.

Turn over by hand 360* adjust the loose rockers again.
put valve covers on and done.

I use to have a set of valve covers with the center cut out just enough to adjust the valves. Not as much of a mess as with out one.

and did it this way...

Brandy Powell

Guyz, its not rocket science, back the adjuster nut off until theres up and down slack on the pushrod, slowly tighten until pushrod doesnt freely spin (you are now at zero lash) then tighten 1 revolution (this puts your hydraulic lifter in the center of its travel) congratulations your done.

NoEmissions84TA

iTrader: (1)

This covers it ALL - correctly!
https://www.centuryperformance.com/v...procedure.html
Below is just part of the article. PLEASE read the entire article for the full explanation.

ENGINE OFF Valve Adjustment Procedure - The Quick and Accurate Way:

First, view this simple chart below for Small and Big Block Chevy Engines. Do you understand what it describes? A more detailed explanation follows below the chart. For other engines you will use the firing order that matches your engine to create a similar chart. This chart is based upon "opposite" cylinders of your firing order. (see below)


Intake Valve Adjustment: ENGINE OFF!

• with #1 cylinder Intake Valve at full valve lift .... Adjust #6 Intake Valve
• with #8 cylinder Intake Valve at full valve lift .... Adjust #5 Intake Valve
• with #4 cylinder Intake Valve at full valve lift .... Adjust #7 Intake Valve
• with #3 cylinder Intake Valve at full valve lift .... Adjust #2 Intake Valve
• with #6 cylinder Intake Valve at full valve lift .... Adjust #1 Intake Valve
• with #5 cylinder Intake Valve at full valve lift .... Adjust #8 Intake Valve
• with #7 cylinder Intake Valve at full valve lift .... Adjust #4 Intake Valve
• with #2 cylinder Intake Valve at full valve lift .... Adjust #3 Intake Valve

Exhaust Valve Adjustment: ENGINE OFF!


You will notice that this is the same procedure and sequence as the intake valves listed above. Only now you are adjusting ONLY the exhaust valves the same way.

• with #1 cylinder Exhaust Valve at full valve lift .... Adjust #6 Exhaust Valve
• with #8 cylinder Exhaust Valve at full valve lift .... Adjust #5 Exhaust Valve
• with #4 cylinder Exhaust Valve at full valve lift .... Adjust #7 Exhaust Valve
• with #3 cylinder Exhaust Valve at full valve lift .... Adjust #2 Exhaust Valve
• with #6 cylinder Exhaust Valve at full valve lift .... Adjust #1 Exhaust Valve
• with #5 cylinder Exhaust Valve at full valve lift .... Adjust #8 Exhaust Valve
• with #7 cylinder Exhaust Valve at full valve lift .... Adjust #4 Exhaust Valve
• with #2 cylinder Exhaust Valve at full valve lift .... Adjust #3 Exhaust Valve

OrangeBird

iTrader: (1)

Brandy , I see your new here , so I'm gonna offer you a friendly , helpful tip ;

Please look at the date of threads you respond to . You have responded to an almost ten year old thread , and I'm reasonably confident that in the nine plus years since the original poster asked his question , he's got the valves adjusted