I know that Comp Cams NSA Pro-Mags are loud but this seems almost too loud. The sound is most definetly coming from inside the engine bay and I believe it to be from the rockers. It ticks not only at idle but also when your driving. The more gas you give it the faster it ticks almost like an exhaust leak. I am absolutely positive that there are no exhaust leaks and I even put my ear up to a screw driver and listened to all the rockers and they all sounded the same. I thought maybe lifter tick but I pulled the valve covers and all the rocker arms are squirting oil just like they should. When I pulled one of the rockers off I did notice that its making a mark straight in the middle of the valve tip like it should because the pushrod length is correct, however it only shows on the firewall side of the tip and not the radiator side. Its got me real puzzled just seeing if its anything obvious that I may not be thinking of...

At idle and with gas:


In the engine bay:

 

This is just a small thing to check, but make sure all the spark plugs are still threaded in nice and tight.

 

Just checked them as well as the header bolts and injectors and everything is tight and right on. Thanks for the idea!

If you kneal down beside the car on either side about where the LT's connect to the Y you can hear it as well. The car just threw a code gotta love them, P0135: bank 1 sensor 1 heater circuit. So now it looks like I need an 02 sensor as well once I trace down this tick.

 

Man, it sure sounds like some REALLY loud lifter clatter to me.....

What kind of lifters are you running, and how tight did you lash them??


I'm running the "dreaded" Comp 875Rs, and even with only 1/8 turn down from "zero lash", set with the engine running, they're fairly quiet.

 

i agree with lead foot, loose rocker arms or lifters

 

Im running the stock lifters with 1/8" turn lash. I tightened down the nut with the set screw backed off on the Pro-Mags by hand until the tip of the roller could no longer go up and down on the valve tip and then added the lash.

 

I know that MANY people will tell you to do it that way, but I disagree. Since I set my first set of hydraulic lifters way back in 1968, the only way I've found to get them set 100% accurately, is to do it with the engine fully warmed up and idling.

In my opinion, it's even more important to do it that way with an aluminum headed engine, as the aluminum heads will expand a bit more when up to operating temp, therefore your setting will change somewhat. The good thing is that LT-1s, at least with the stock oil pump, don't pump a lot of oil at idle, so it isn't like the "old days", where YOU'D take a hot oil bath, as well as coat the entire engine bay and garage floor/driveway with oil.


Another thing to consider, is if you adjust the valves without the engine running, there is a tendency for some of the lifters to "bleed down" before you get to them, so potentially, you could over tighten those lifters that are the last to be done. In your video, however, that doesn't sound like they're too tight. But then again, if they were, you'd have "zero" slack in the valve train once the lifters tried to fill up with oil, possibly causing the valves not to close completely, and "pop-back" through the intake/exhaust ports. That, I suppose would create some strange sounds also....

 

Tonight Im planning on attempting to readjust the valves with the car idling and see what happens. I tried to do so the other night but with all the loud noise I couldn't tell when the rocker was loose enough that it would "clack" and then be able to know that I would need to then slowly tighten it until the "clack" stops then add my preload.

 

Good luck with it! If that's truly what is being heard on your vid clip, they are pretty loose right now. You might want your first move to be tightening them down....slowly, of course.


BTW, what kind of poly locks are you using? I've got the ARP pieces on my car, and they say to torque the "set screw" in the adjustment nut to 22 ft./lbs. That will keep them from backing off!

 

when the last time you adjusted them? it sounds like the lifter was not on the base of the cam when they were adjusted. thats how mine sounded the first time i adjusted valves. turn out the cam was not in the correct position when i did it. once i figured out what was wrong i adjusted them again and they were quiet.

you might also want to run a little more preload. 1/8 isnt much. try 1/4 turn

 

Im using the poly locks that came with the rockers. I would like to buy the ARP's b/c I have heard of them backing off so that will be the next thing. Im 100% certain now that the noise is coming from the rockers/lifters. Im sure readjusting the valves will solve the issue. Only thing is, when I adjust them if oil is not squirting out then I'll need to replace the lifters. When I first popped a valve cover off I noticed 2 that were not squirting oil which got me thinking that they may be clogged, only way to tell is to do it and I will see. Thanks for your help!

 

i have the same ticking sound. sounds like a lifter, so i just went around the rockers adjusting the sets for #1 and #6TDC. didnt bother backing off the nuts, just tightened them . helped a little, but its still there

 

I adjusted them a little while ago but the car hasn't been started in a few weeks so its only ran for a total of say an hour at max with the valves like this.

So you adjusted the valves at say cylinder #1 when that cylinder may not have been at TDC? What you did gives me light that this noise will go away once I readjust them!

 

If you want to try the ARP poly locks, be advised that they probably won't clear the stock, stamped valve covers. The 12 point hex they have on top is the "kat's azz" for getting an adjustment wrench on them, but it adds about 3/8-1/2" of height to them. Then the OE covers won't bolt completely down...they miss by about 1/16" or so. I used them, but wound up modifying a set of the Proform tall, black valve covers. I cut the notch in the RH cover to clear the alternator, then formed and welded in a "patch" to cover the slice I took out. However, I seem to have a minor issue with getting that valve cover to completely seal up correctly.





Not to be sarcastic, but this is the problem I've found by setting the valves with the engine off. It's VERY easy to get just a little off, especially because the LT-1 doesn't have timing marks on the pulley or a timing tab to use as a reference. Therefore, it becomes somewhat "hit or miss"....

With respect to preload, 1/4 to 1/2 turn is good for OE lifters. As I previously mentioned, I have the Comp 875s, and they don't have as much plunger travel, so 1/8 turn is what Comp recommends. Believe me, I had to mess with it a couple of times to get it "right on", as 1/8 turn isn't a lot of preload, but with so little plunger travel, it has to be there. I started with 1/8, thought they were a little noisy, went to 1/4 turn, but got discussing this with someone else here, who pointed out that the 875Rs were, what we called in the "old days", an anti pump-up lifter, hence the lesser pre-load. I was told that too much pre load on this particular lifter would destroy them.


One other thing, if you didn't get any oil up the pushrod, it could be an indication of too loose a lifter setting, The oil flows up through the lifter, as it's pumped through the lifter gallery. If there's too much clearence between the cup in the lifter and the pushrod, there isn't a tight seal between the pushrod and lifter, and the oil can "bleed off" through that additional gap.

 

I will be following this since I also have a annoying ticking noise from the valvecovers since I installed pro-mags NSA, its a little bit quieter than yours but still annoying.

Have you checked the clearence between the pushrod and the bottom of the "U" on the guideplate? As this can cause a ticking sound.

 

Krill, some aftermarket rocker arms are wider, and/or taller than others. If you're using the stock valve covers, have you checked for clearance inside them? It's possible that the rockers are hitting the internal bracing of the covers.

 

(assuming stock lifters) 1/8 turn lash is not enough when i set mine, i used 1/2 turn.

http://shbox.com/1/4th_gen_tech2.html#adjust_valves

refer to adjusting valves and zero lash it calls for 1/2-3/4 turn past zero lash for stock lifters.

 

Thanks for the thought, but I have the LT4 covers and they have plenty of clearence.

The one thing I havent tried yet is to put a stethoscope on each guideplate to listen for extraordinary noise.

Maybe its just BS and I shouldnt care but it is driving me nuts!! My dad says he cant hear it

 

Let me ask you this, as there was a similar discussion recently...Are you, by any chance, using guide plates with self-adjusting rockers?? It's generally recommended not to....

 

I have always heard that as well but Lloyd Elliot told me I want to do a 1/16"-1/8" turn preload on them with my particular setup. I put 1/8" on them when cold and that wasn't where it needed to be so we shall see.