Camaro 3.4 Valve Adjustment Problem

[camaro94man]

I bought a 94 Camaro 3.4 for $800 with some valve train noise. When I got it home he valave covers were removed and the intake rocker was extremely loose. All others had had zero play in them. Instead of just tightening the one loose rocker I decided to adjust each rocker for a lil preventative maintanence. I followed the repair manuals instructions positioned he balanced arrow at 12 o'clock when both rockers on cylinder number 1 had closed the valves, I did not actually put something in the spark our whole to make sure it was a TDC on the compression stroke so this could be were I messed up. I then loosened each rocker and tightened then untill there was zero lash on the pushrod, not using the side to side method but I used the up and down merged, I then tightened each rocker 1 whole additional turn, this was done on on six valves according to the book and then the engine was rotated one additional revolution and the remaining six were adjusted, I can't remember which ones were adjusted in which order but I am positive that it was the correct order because I followed the books instructions and double checked it multiple times. After adjustment the rocker that was originally loose has alot more threads showing on he rocker stud than all the other ones, all the other ones have the same amount of threads showing. When I put the motor back together the loud valve train noise is completely gone but now the engine runs really rough and smokes alot. Before I took the engine apart it ran perfectly but only had a noise from that loose rocker, now that I fixed the rocker the noise is gone but the engine runs really rough but makes no noise and smokes. What happened? Could I have adjusted the valves incorrectly? Thats the only thing I can think of? What is the correct way to adjust the valves in this car? It is a 94 camaro 3.4 liter. Help! Im lost, I don't see how I could have done it wrong when I followed the book exactly. The only thing I can thing of is maybe the engine wasn't on top dead center on cylinder number 1 when I started off. This time I will stick my finger in the hole and make sure that it is on the compression stroke and top dead center when I start. But could the valves make the engine smoke if they are adjusted wrong? And im sure they could make it run the way it is.

[bszopi]

First off, welcome to the site!

Check in these 2 articles on the proper way to set lash. And just an FYI, the manual is wrong...

http://60degreev6.com/forum/showthread.php/46231-Valve-lash?highlight=camaro+valve+adjustment

http://60degreev6.com/forum/showthread.php/44066-Stupid-3.4L-valve-adjustment?highlight=camaro+valve+adjustment

Hope that helps!

[camaro94man]

That was pretty helpful, thanks!

Im still a little worried as to why the rocker arm stud has more threads showing on the #6 cylinder intake rocker stud than all the others. And not only do the others have fewer threads showing, but they each have about the same amount of threads showing as well. If the rocker arm stud on #6 has more threads showing than the others, then doesn't that mean that the rocker is tightened down further than the others, and wouldn't that mean that it is opening the valve more than the others? Or that the pushrod is pushed down further than the others? Its got to mean one or the other! And why would it be doing this? Can the lifter plunger for that pushrod be stuck and allowing me to tighten that rocker down further than it needs to be? Any suggestions?

Also, would the valves being misadjusted cause the engine to smoke obsesively? It smokes alot now that I have put it back together, white smoke, also it is strong and smells like fuel.

Im going to try to adjust the valves using my finger in the spark plug hole to determine top dead center on compression stroke on cylinder #1 and then turn the engine and adjust the valves on each cylinder going by firing order. Also, im only gunna turn them 3/4 of a turn instead of 1-1/2 after zero lash. Still worried about the #6 cylinder intake rocker arm stud having so much more threads showing than the others, by the way, the #6 cylinder intake rocker was the loose rocker that caused me to take the engine apart in the first place to fix the noise it was making.

Please help! This is the first time ive used these forums and am very impressed so far! Thanks!

[bszopi]

I wouldn't worry to much about the thread count (although I personally have never worked on an iron head motor). It may just be that that stud is longer than all of the others. As far as the smoking and what not, I'm not sure. Hopefully someone else can chime in there.

Glad your experience on the forums has been good so far. That always pleases me.

[86FieroSEv6]

Excessive rocker stud thread reveal can also mean that particular hydraulic lifter is collapsed. If raw fuel is getting dumped into the motor it will run in the manner you have described. If that lifter is collapsed, when you took it to zero lash it would have been bottomed out and your extra turn is holding the valve off it's seat. Back that one off till you can just shake the pushrod and try running the engine again.

[camaro94man]

Any reason why that stud would be longer than all the others? Im sure that's not factory, and its just weird that it is the same stud that corrosponds with the loose noisy rocker.

[camaro94man]

Thanks 86! This sounds like the most likely cause of my problem.

If your theory is true, and that valve is hanging open because of it being overtightened and has more threads showing, could it be anything other than the lifter being collapsed, or would that pretty much mean that the lifter is where my trouble is at?

And so the valve being hung slighty open can cause the engine to smoke? And obviosly it will cause it to run rough.

[camaro94man]

Also, if the lifter is collapsed will I be able to tell when I remove it and look at it? How can I tell?

[geoffinbc]

Sounds like a collapsed/stuck lifter. Lifters have the tightest clearance of any part in the motor. Any small amount of gunk can make them stick.

Find that rocker and put the lifter on the base circle of the cam (valve closed) and remove the spring load do the same to any other good intake rocker that is in the same position. A good lifter will rebound and the pushrod will be a certain distance above the guideplate. Now compare the bad one to the good one. If it is significantly lower the lifter is toast. Replacement is the quickest option. While you at it just replace all of then a do a normal cam break in procedure. Make sure you use break in oil and moly lube on the new lifters.

[camaro94man]

Ok, im gunna tear the engine back down today and replace the lifters. I've heard that hu are supposed to soak the lifters i'm oil before installing them, but I've also heard that is not necessary.

Let me make sure I've got this right. Im going to put the engine on TDC for cylinder #1. Then loosen all the rockers and remove the pushrods. Ill take the intake off and try to get the lifters out wit a magnet or however I can get them out without scratching things. Then just install the new lifters without soaking then in oil overnight but I will at least make sure to put some start up grease on them. Then ill put the pushrods back and tighten the six rockers that the book says to zero lash and then 3/4 of a turn. Then rotate the engine one full turn to put #4 on TDC and tighten the remaining six rockers to zero lash and 3/4 or a turn.

Is this the correct procedure?

Thanks everyone for all your help! I will be pulling an all nighter on this one tonight so ill post the results tomorrow in the morning. Wish me luck!

[Ed_Mc.]

Be sure to carefully inspect the cam lobe for the suspect lifter. If the cam is 'flat' or has any damage to the lobes you're gonna need to replace it as well. Of course, this opens up a bigger can of worms and you're tearing into the timing cover etc. If that happens, it'd be a good idea to renew the timing set, timing chain dampener, and the water pump while you're at it.

HTH & G'luck...........ed

[86FieroSEv6]

Right on, I forgot about flat cam lobes. There was a period of bad cams all around due to problems with the metal. Of course, we didn't find out about it till much later and many thousands of cam swaps. If the OP was turning the engine by hand and saw the rocker/push rod move up and down a similar distance to the others then that would be ruled out. A cheap magnetic base dial indicator comes in handy for this type of verification.

[geoffinbc]

I never follow the adjustment procedure in the manual. I like the cylinder by cylinder method that COMP cams recommends. Rotate the cam until the exhaust valve begins to open. Stop. Adjust the intake valve. Rotate the engine again until the intake valve opens all the way and then begins to close. Stop. Adjust the exhaust valve. Do the same for every cylinder.

For stock studs adjust the lifter preload 1 turn past zero lash. Stock studs have a 1mm thread pitch which is very fine and 1/2 or 3/4 turn is not quite enough preload.

[camaro94man]

Thanks everyone, the lifter for the #6 cylinder intake side was definately collapsed! Many more look stuck. Cam lobes looked fine, I replaced each lifter and tightened the rockers 3/4 turn past zero lash.

The engine runs a whole lot better, no smoke, no miss really, it has a little hesitation and idles high now but I think I may have some vacuum hose issue.

There are two cables run to the throttle body linkage, one is from the gas pedal to open the throttle body when you press the gas pedal, the other is disconnected and wont go back on. Im not sure what it does? My first guess was that maybe it was a kick down cable but the car is not an automatic, its a standard shift. Could the car maybe at one point been an automatic? Or does this second cable do something? This is a 94 camaro with the 3.4 in it and is a stick shift. Why are there two cables fun to the throttle body?

[bszopi]

The 2nd cable on a TB is usually for cruise control.