94 LT1
110k miles

I took the Vette out for the first time since winter.

I drove around 50 miles. I noticed that at hot idle (oil and water temp both around 180) on occassion I would get some valvetrain ticking/tapping sounds. The loud ticking doesn't start immediately at idle. I can come to a stop and idle without much noise for 10-15 seconds and then I will notice it will start to tick. The valvetrain also seemed a tad noisy while driving as well but I couldn't hear the 'ticking' that I can at idle. If I bring the engine rpm up above idle the ticking seems to go away, though it still has some mechanical valvetrain sound (roller rockers). I use Mobil 1 5w30. The level was right at the full mark but this is last seasons oil - I have not changed it yet.

The motor is stock but has 1.6 roller rockers that I installed last year. I know roller rockers make more mechanical noise than the stamped rockers but this seems excessive. I seem to remember this intermittent tap from last season as well. And it started after the RR install. Is this normal for roller rockers or does my lash need to be adjusted? The only way I could get it to run queit when I installed the roller rockers was to adjust them with the motor running. Perhaps I need to run the motor up to temp and get the oil very hot before adjusting. Could this be a lifter issue? Maybe one that bleeds down at idle? It doesn't sound like ALL the rockers making this noise either, it seems like it is only 1 or 2.

thoughts?

 

I would try readjusting the valves, warm engine running, first. You might want to switch to 10w-30 oil with that milage.

 

Above are the highlights from your origional post. It seems as if you've answered your own question.

Help us narrow down the issue - what other valvetrain components did you reuse/change when the 1.6 rockers went on?

Valvetrain geometry was "good" after the 1.6 went on?

Any idea of the overall "preload" used to make the adjustments?

 

To address both of the above posts...

First why move to the heavier weight oil? Especially since when hot, both should behave like a 30w. The car doesnt burn, leak or consume any oil at all. I've always been a stickler about running the weight oil that the manufacturer recommends. A lot of people seem to be of the thought that an older motor will have worn out tolerances and would benefit from the cushioning effect of a thicker oil. But, I'm of the opinion that just because a motor is old doesn't mean it is worn or has sloppy tolerances, and changing to a 10w30 I believe would only mean that at low oil temperatures it would be like a heavier viscosity oil and once up to temp both 10w30 and 5w30 should behave like a 30w oil. Is there other reason to switch to 10w30? Is my logic incorrect?

And second post...
-Summit Racing house brand 1.6 self aligning roller rockers (made by Scorpion I believe)
-LT4 hotcam springs
-replaced valve stem seals (felpro brand I believe)
-reused stock pushrods and lifters (110k miles)

As far as geometry, I assume you mean where the roller tip is contacting the valvestem? To be honest, I didn't check to see if it was centered. Everything I had read at that time said 1.6RR on a stock cam will have no geometry issues.

With the motor running I adjusted each rocker arm individually until it stopped tapping. I would use a screwdriver, the metal end against the rocker arm stud and the plastic end to my ear, to isolate the tapping noises from that rocker. Doing so allowed me to tighten each rocker just enough so that it was quiet. Once a rocker was sufficiently tight so that it did not tap, I added 1 turn of preload and then secured the poly lock.

Would a good starting point be to change the oil (I plan on it anyway since I'm at the start of a new season but should I really go to 10w30?), run it till the oil gets up to temp, and then adjust the rocker arms with motor running again? Is 1 turn of preload after a rocker quiets down sufficient? From what I remember the new rocker arms did not come with any documentation or suggestion for preload.

 

I will just add one quick comment. Last year when I installed my new motor the 1.6 rockers were fairly quiet. Now that I have over 6000 miles on the motor the rockers have started to make a little more noise even after adjustment, I believe after the rockers ( break in) and tolerences open up a small amount you will get more noise. I have talked to others that said there rockers have done the same thing so Im not to worried.In the last few months there have been numerous posts on here talking about alum roller rockers being noisy, I just think its the nature of alum roller rockers to be noisy ...WW

 

Better safe than sorry-

Pull the covers and visually check for obvious issues.

Check the geometry:


Readjust the valvetrain if problems persist and no other issues turn up.

Finding "0" lash is best done with the engine shut "off" - my opinion.

 

Sounds like your adjustment is just fine and agree with WW7

Well it doesnt stay factory new forever, those tolerances will open up a bit. 100k isnt destined for the machine shop but sure its somewhat loose.
Wouldnt worry about it change the oil and drive it.

A motor with 100k will use some oil maybe not as much as some but not 0. See that posted a lot. Doesnt matter though..

 

Thanks for posting, definetly appreciated.
I can't sum this up as any normal wear in noise. It sounds almost like someone rapping on a metal bracket under the hood maybe twice a second at hot idle. Its a high pitch 'tick' sound. It is definetly valvetrain - not anything in the bottom end. Raise the revs a few hundred rpm and the noise is gone. I may pull the valvecovers over the weekend and see if I can identify a a suspect rocker.

And I understand any motor uses some oil, but by zero oil what I mean is that at the beginning of the 2010 driving season I changed the oil. Now, at the beginning of the 2011 season it still has the same oil as the 2010 change and the dipstick is right at the top of the full hash, never had to add any. So, my point is it is running normally, not consuming a lof of oil. Yes, it isn't factory new, but the question I am posing is that it seems mechanically sound (except for this occasional top end tick) so do I really need to extra cushion of a heavier weight oil or am I better off with the factory recommended viscosity?

 

Most run a little heavier weight as the engine wears doesnt mean you have to though.

When you increase the rate the valve is opening and closing you are bound to get some noise and at idle warm youll probably hear it most.
Guys with those fast ramp cams AND 1.6 on top of it complain the most. Mine sounded like it was going to explode under the valve covers sometimes it was "normal" though if that helps

 

Ok, I feel a little better about it now!
It was just hard to accept that it made no noise before and now I get an occassional tap.

I will likely still bring it up to temp and pull the valve covers in an attempt to identify a noisy rocker. If I find it then I can at least try to reset the preload on it. I have nothing to lose. I've already made my 5w30 mobil 1 purchase for this seasons oil change so I'll likely stick with that at least for now. Maybe next year I'll try 10w30.

 

10w30 and 5w30 are both 30 weight oils once warm. If you want to use a higher viscosity oil look for a 40w.

 

If you dont find anything wrong. Turn your stereo up louder like I do.
Just kidding, but you might not find much.