I think I have it right, but I wanted to double check before I put it all together. This is on the 2.8. You set the mark to TDC for the first piston, then tighten down number one valves until the rod stops spinning. This means it is seated. Then (According to the Chilton Manual) You tighten it down 3/4 of a turn. Then continue turning the crank for the other timing marks in order, the three timing marks first time aroud are 1,2,3, then the timing marks second time around are 4,5 and 6. Is this completely correct, or am I forgetting something? I really don't want to have to dig down to my valve covers again. Thanks.

Strange my hynes manual said 1 1/2 turns after seating it. It seems to have worked

Oh really? The guy that built my engine told me to do 3/4 of a turn. I told him that I've seen people say to put it at 1 1/2, but he said I should stay with 3/4 cause I don't want to bury the rod in the engine and blow something up. I think it also has to do with the top end on my car. The rockers, rods, and springs are off a 350, so would that have an effect on how much to turn the lash nut down?

unfortunately I don't know if that makes a difference. I'd think it might. I'll check my factory manual to see if it says the same thing my haynes says. If the rods are the same length as stock it should be the same adjustment I think.

That would be a great help! Thanks a lot!

Guys, I've seen this topics on here many times and from what is in the archives is the GM factory manual is wrong. Even the Haynes manual is wrong but the same as the factory manual indicates. I had my engine out of my fiero and I was told that 1/2 to 3/4 turns is plenty...and that's after the push-rod is contacting the rocker arm and doesn't have play in the up-and-down position. (No lash) Once there is no play, then tighten 3/4 turn max.

I have never adjusted the lash on a fiero V6 engine, but MANY folks have said you can collapse the lifters if someone tightens to 1 1/2 turns. GM is wrong.
Really, I don't know why GM screwed up on this info, but hopefully someone can clairify this.

Someone speak up if this method is off.

Thanks,

I actually measured the travel with 1.5:1 rockers on all 12 lifters and 1.5 turns centers the lifter. If you don't want it centered in the lifter travel, use fewer turns.

I use 1.5T and have never had a problem over several different 2.8 and 3.1L 660 engines.

TK

my factory manual also says 1.5 turns. I just did this Saturday and have had no problems. You may benefit by being a bit conservative and go with 1 turn. You wont hurt your engine either way between .75 and 1.5 turns. Just do your thing however and go drive your car!

Where do you live?
Edit: aww wrong Washington or I'd be happy to wrench with you

[This message has been edited by MarineFiero (edited 10-29-2008).]

Back to your first post, wanted to make sure what you did.
When you had #1 at TDC did you adjust only Exhaust on 1, 2, 3 and Intake on 1, 5, 6
then turn 360 and do Exhaust on 4, 5, 6 and Intake on 2,3,4

Just wanted to make sure you did not adjust both intake and exhaust valves on each cyl at the same time since 1 and 4 are the only cyl. you can do that on.

Hope that makes since...

The old-school method of adjusting valves with hydraulic lifters was to do it with the engine running. For a high performance adjustment lets use a 60 Pontiac V8 as an example since I have one.

Warm up engine first. Then pull one valve cover which takes less than a minute,, honest. Start engine and let it idle. Oh, by the way this would require a set of special rocker nuts that have an allen screw in the center to lock the nut in place.

Anyway just start at the front rocker and back off the nut slowly until you hear the rocker start to clatter. This means the plunger in the lifter is at its highest position. Being loose at this point will cause the oil coming up thru the push rod to spurt around some so slowly tighten the nut back down til the clatter goes away then give it a half turn more and lock it in place wiith the allen set screw while holding the nut in place with a wrench. Then move on to the other rocker. Chevy rocker nuts are tight all the way up & down the rocker stud but Pontiacs were not, hence the special nuts.

Once the job is all done a higher rpm will be noticed and a adjustment of the idle screw would bring it back to spec. The engine will also rev up a lot faster. Almost like having solid lifters without the lash.

With this type adjustment and 2 shims "forget what .000th" under each valve spring I could rev to 6200 rpm without floating a valve, something unheard of with a dinosaur of those days.

I can't imagine using this method on a Fiero 2.8 due to the mid engine and the fact that oil would be flying all over the place "fire potential" and the computer would be throwing every code its got trying to figure out what the hells going on.

But you get the idea. The higher the plunger in the lifter bore the better. Go to tight the other way and you can bend a push rod or worse.

Spoon

Not wanting to hyjack here but I have a related question.

Are we talking about dry lifters here? Years ago I used to soak new lifters in oil for a day or so before install and setting the valve lash. I seem to remember that this was required on early Rhoads lfters? I ask because I have a fresh 2.8 that has been sitting for awhile. I too want to set the valve lash before I button everything up and stuff it in the car. I did fill the crank case with oil and spun the oil pump with a drill a few times to get oil pumped up to the lifters. On SBC's, I have seen catastrophic lifter and cam damage as a result of valve lash being set to tight.

As for 3/4 turn or 1 1/2 turn, I do not know. If you are using a 1.6 rocker, I would think you would want less turn to keep from bottoming out the lifter and/or bending a push rod. Same with a higher than stock lift cam. I would also think that if you are using other than stock cam, there should have been instructions from the manufacturer for setting valve lash. It's been about 15 years since I built a motor and my mind is alot more rusty these days.

Pat

Guys, have a look in the archives...there is lots of debate about this.

The guy that set my lash on my engine has lots of "fiero" knowledge, and he doesn't just know the history or about the fiero, he works on fieros mostly every week. He also mentioned the GM service manual is wrong. Mine was re-checked for the valve lash just incase the lash was to tight. I just wanted my camshaft to last instead of having problems due to this mis-undestanding.

Have a look...

------------------
fierogt28

88 GT, loaded, 5-speed

quote Originally posted by katatak: ... If you are using a 1.6 rocker, I would think you would want less turn to keep from bottoming out the lifter and/or bending a push rod. Same with a higher than stock lift cam. I would also think that if you are using other than stock cam, there should have been instructions from the manufacturer for setting valve lash. It's been about 15 years since I built a motor and my mind is alot more rusty these days. Pat

I did it with 1.6:1 rockers too and it's 1.3 turns to center them.

If the service manual is wrong, it's been wrong since 1980.

[This message has been edited by TK (edited 10-30-2008).]

quote Originally posted by TK: I actually measured the travel with 1.5:1 rockers on all 12 lifters and 1.5 turns centers the lifter.

Exactly! The most common problem is that many people aren't very good at finding the zero-lash point. If you do it right, the value (1.5 turns) in the GM/Helm manual is correct.

(What a novel idea ... actually measuring things for yourself! There's no substitute for your own data.)

quote Originally posted by F355: This is on the 2.8. You set the mark to TDC for the first piston, then tighten down number one valves until the rod stops spinning.

If you mean this (i.e. "the rod stops spinning) literally, then you are doing it wrong. "When the rod stops spinning," it means that you have gone way past the zero-lash point and have bottomed out the lifter; go any further and the valves will never close completely.

What you want to find is the zero-lash point. When looser than zero lash, the pushrod will be loose and "rattly," and it will spin very easily. At the zero-lash point, the looseness will abruptly disappear, and there will be an ever-so-slight increase in the force necessary to spin the pushrod. The key words here are "ever so slight increase" in drag.

[This message has been edited by Marvin McInnis (edited 10-30-2008).]

Well the big thing is, I have the top end of a 350 on this engine. Valves, rockers, springs, everything. And responding to a lot of people, ya i'm in Washington, yeah I adjusted both intake and exhaust while being on TDC for that particular piston. I would have to agree with the manuals that 1 1/2 turns would be ideal for a stock application Fiero, but I think with my set up having the stems on the valves much longer, I should keep it with the 3/4 turn.

quote Originally posted by F355: As soon as I couldn't spin it ...

If you can't still spin the pushrod easily, with only slightly more drag than in the original loose condition, then it's bottomed out in the lifter. That is bad.

Hope this helps.

quote Originally posted by F355: I found this from jetman.

How I've adjusted my valves:

First of all let me give credit to where it is due. JazzMan and a couple of other PFF members actually wrote a good portion of this, I cut, pasted, wrote and edited this so that my non-mechanical brain could easily follow it. That said, let’s get busy adjusting some valves.

The idea is to get the lifter poppet part way down into its bore, about 1/4-1/2 of its travel. If you don't use up some of its travel, then your valve(s) will get loose as normal wear on valve-train parts causes the poppet to reach the top of it's travel. It will also requires more oil to remain (at pressure) in the lifter's plunger cylinder. The more volume to fill, the more chance that the plunger can be compressed, causing a ticking noise or at high revs a bent pushrod.


Make sure that the lifter being adjusted is on the base circle of the cam, this will be TDC on that piston with both valves closed. TDC #1 is where both #1 valves are closed and main fat timing mark on harmonic balancer is at zero on timing tab and distributor rotor is pointing at the number one plug wire terminal.
Set your intake and exhaust valve lash on #1. Rotate the harmonic balancer clockwise 120* to the next timing mark and you know that you are at #2 TDC. Set your intake and exhaust valve lash on #2. The next timing mark after that is #3 TDC and so forth. Remember that the GM/Fiero engines have three timing marks (0*, 120* and 240*) on the harmonic balancer, which makes this much easier than the Chiltons manual method.

The lifter plunger centering adjustment is 1&1/2 turns. Most people think is too much. It is not. The 1&1/2 turns (as specified in the FSM) will center the lifter plunger on an OEM valve train (with the standard rocker ratio). The reason most think that 1&1/2 turns is too much is because they don't properly identify the zero lash point. If you are twirling the pushrod you won't be able feel the zero lash point unless your hands are 100 times (give or take) more sensitive than the average human. Anyway, while approaching the zero lash point, you should be gently rocking the pushrod up & down between the lifter and the rocker arm. That way you can feel the play diminish down to zero.

Wiggle the pushrod back and forth as you tighten the rocker nut, you will feel the pushrod end "clicking" as it moves around. The amount of movement will decrease as the nut is tightened until suddenly it stops. This is the point where the lash is out with the poppet at the top of it's bore. Now, you need to move the poppet down its bore, so you continue to tighten the rocker nut.

How much you ask? Well, the rocker stud has a 1.5mm pitch, so one full turn moves the rocker ball down 1.5mm. The rocker arm ratio (stock) is 1.5:1, so moving the rocker ball down 1.5mm moves the pushrod down 1.67x1.5mm, or 2.5mm plus or minus a very tiny bit. The lifter poppet travel is 6-8mm, so 1.5 turns on the rocker nut (factory spec) is 3.8mm at the lifter poppet, or about half-way. That's how much I tightened mine, and it worked just fine. Any less and the valves will need readjustment sooner due to wear.

I had mechanics using the Chilton’s manual mess up the lash, I tried the twirl and ¾ turn method and it was noisy as marbles. Jazzman gave me the pitch and rocker ratio measurements above and I went with timing marks on the balancer and the 1-1/2 turns on rocker arms. My engine is smooth now. Lots of power. Most important to me is that I wont have to go through the work to tear the upper half of the engine out to get the lash adjusted for a very long time. Some people have had success with other methods, all the power to you. If there is an easier way, count me in! Good luck with setting your lash and I hope you are using the rubber valve cover gaskets, they are sweet and don’t leak.

quote Originally posted by F355: Wait... My mechanic said that I should spin the rod in my hand with just two fingers lightly. As soon as I couldn't spin it, i tighten it down 3/4 cause then it's seated.

I do it this way,

Since the lifter and rocker are dished to keep the push rod captured, I lightly hold the push rod down on the lifter while wiggling the top back and forth in the rocker. Gravity will usually hold the push rod at the center of the lifter. If not, you can feel when the push rod is in the lifter center.

As I tighten the rocker, the push rod is forced into the center of that rocker dish. You can feel and hear when the push rod is at the center of the dished area (clicking and play stops). I then back off the rocker some until it clicks again and crank it down once again until it stops. That is zero lash. You will certainly be able to spin the push rod but there is no play between the lifter and rocker.

I stopped using the turning method (spinning the push rod) because any lube on the the lifter dish or rocker dish will allow you to spin the push rod even though you've already started to press the lifter down. I think this burns you most when the lifters are dry or not completely filled with oil. If the lifters are pumped up completely then the push rod is more likely to stop rotating at zero lash. Using this method of checking for any free play, you don't need to worry if the lifter is dry or full or inbetween.

Then I crank to 1.5T for 1.5:1 rockers or 1.3T for 1.6:1 rockers on the 660 engine. Obviously, different engines have different specs.

[This message has been edited by TK (edited 10-31-2008).]

I used the wiggle method to set zero on my 3.4 also.
I had put in a new cam and lifters and had set the lash to 3/4 of a turn.
After running the engine for several K I was getting increased lifter clatter.
I pulled all back off and re-lashed to between 1 and 1-1/2 and is much better now..
The breakin of the cam and lifters showed that 3/4 must have been just on the starting edge of being enough lash

Once zero lash has been achieved and the nut further tightened correctly, should the pushrod still be able to twist between your fingers?

Mine will still spin when the valve is closed. There is friction, yes, but it will still turn with some effort.

quote Originally posted by fierogt28: Guys, I've seen this topics on here many times and from what is in the archives is the GM factory manual is wrong. Even the Haynes manual is wrong but the same as the factory manual indicates. I had my engine out of my fiero and I was told that 1/2 to 3/4 turns is plenty...and that's after the push-rod is contacting the rocker arm and doesn't have play in the up-and-down position. (No lash) Once there is no play, then tighten 3/4 turn max. I have never adjusted the lash on a fiero V6 engine, but MANY folks have said you can collapse the lifters if someone tightens to 1 1/2 turns. GM is wrong. Really, I don't know why GM screwed up on this info, but hopefully someone can clairify this. Someone speak up if this method is off. Thanks,

GM didn't screw up anything, their info is accurate. The problem is that most people can't tell by twisting when they get to zero lash and end up over-tightening the rockers big-time, especially if the lifters are dry or have little oil in them. 1.5 turns after accurate determination of zero lash puts the lifter poppet exactly in the center of it's range of travel.

I find that holding the pushrod up against the rocker to remove slack and then clicking the bottom of the pushrod back and forth in the lifter poppet seat works best. You can feel the click distance decrease until suddenly it's gone, without any downforce against the lifter at all. Tighten the rocker 1.5 turns past that and you're done.

If you tighten the rocker while twisting until the pushrod gets hard to turn you've either bottomed the lifter, in which case your engine won't run and your cam will be wrecked in the first 30 seconds of trying to start the motor, or if there was oil in the lifter the adjustment will be at some random point which may or may not work and may or may not have enough travel in it to compensate for thermal/wear changes down the road.

JazzMan

quote Originally posted by JazzMan: GM didn't screw up anything, their info is accurate. The problem is that most people can't tell by twisting when they get to zero lash and end up over-tightening the rockers big-time ...

JazzMan is 100% correct. Listen to him.

ok to stay on topic will this work on a duke? mine sounds like marbles in a metal coffee can on the handle bars of a bike driving on the rumble strip of a highway.

Aren't SBC rocker studs different than 2.8 studs? I thought the thread pitch was different - needing less turns.

yes that was the point I see that was missed. he has 350 rockers AND studs. they are a course thread on the adjuster and in that case 3/4 turn is correct. the stock fiero stud is a fine thread of higher pitch, so requires more turnse to go the same distance.
the side to sidemovement of the pushrod while held up tight against the rocker and feeling the "tick" as it hits the sides of the cup is the most acurate way to find 0 lash on an assembled motor. when you feel it just hit no movement on the lifter cup stop, and then do your 3/4 turn in for the sbc studs. if you have a higher ratio rocker, reduce the number of turns by the percentage increase over stock rocker ratio. sometimes hard to do very accurately wihout a degree wheel, but there is some leeway with hydraulic lifters.
on a cold motor, I tend to go just shy of the number of turns ie about 1.65 turns stock to allow for expansion.

quote Originally posted by 85duke: ok to stay on topic will this work on a duke? mine sounds like marbles in a metal coffee can on the handle bars of a bike driving on the rumble strip of a highway.

The valve train on the Duke is non-adjustable. All the clearances and lengths are designed so that you just tighten until tight then use a torque wrench to make sure it's the correct tightness to keep them from coming loose. If you alter the geometry by milling the head/block or using a non-OEM thickness on the head gaskets you have to modify parts to make it adjustable, though sometimes you can shim the rocker studs. That sound is normal for worn Dukes. Heck, it's fairly typical for new Dukes.

JazzMan

quote Originally posted by tjm4fun: yes that was the point I see that was missed.

Wahoo! I finally gave some help! - and having tjmfun back it up is a good feeling. heh-heh.

This has been a really helpful thread. I have often wondered about the number of turns and I think I now understand my previous problems. Although I have had motors run fine after the "twisting" method I believe that it is deceptive as I have encountered the same issues as posted above (not sure where the zero lash was). I'm working on one now and plan on using the "rattle" method as described above. Thank you again!