I've got an odd valvetrain noise that's been showing up every now and then. I'll run through the history of things:

~15K miles ago, I installed Comp 918 springs. I drove around for a weekend with no issues at all, before I installed a used Comp XE-R like .550" cam.

Upon startup, things were fine for about 10 seconds. Then a loud knock started. It sounded like a lifter needed to be pumped up, but I'm not sure if that was the case or not. Within another ~10 seconds it almost completely cleared up... but never quite did completely. I was plauged with a good amount of valvetrain noise after that.

The VT noise was so "noticeable" at times, it was plain as day to hear in parking garages, tunnels, and driving next to jersey-barriers. I found it embarassing.

The noise was a rather ill-sounding tap (a lot like piston slap), along with a "scissor-like" noise which I supposed could be associated with a sewing machine. It would come and go as it pleased, with me being unable to duplicate it to any degree. When it was present (somewhat often), it was noticeable throughout the "daily driving" type RPM ranges.

I then swapped the cam out for my current one. Slightly more advertised duration on one side, less at .050 on both, on a .531" yielding lobe. The valvetrain noise was nearly gone. Every once in a while I'd hear a hint of it, but it was never enough to bother me at all. It was just a very-very faint scissor-like noise.

I recently installed higher ratio rockers (with guide-plates) yielding about .560" at the valve on the same cam as above. The scissor-like noise has re-appeared a few times.

The other way I could describe it would be to call it a "piffing" noise. "piff piff piff piff".

When it's present, it is a little noticeable at idle abut more at parking lot speeds. It will be noticeable when you let off the throttle, once out driving on the road (either highway or side roads). Once you get on the throttle more than enough to get out of your own way, it clears right up.

I feel as though it effects the performance of the motor. It seems to feel sluggish and not as responsive with throttle changes.

I don't *believe* this to be your typical valvetrain noise from aggresive valve action... is it?

What are the chances I could have damaged a lifter upon installing the first cam?

What are the chances a lifter could have damaged itself, if it didn't recieve oil in time and pump itself up quickly enough?

Any other thoughts?

A cracked 918, in a place that's mainly letting it operate as normal? I looked over the springs when I had the first cam in there. Everything looked okay, but I honestly wasn't trying too hard. You would have thought I would have looked things over again when installing the rockers, but this was definitely not on my mind at the time.

I can cofidently say it's not exhaust-leak related. The headers were installed between this, with all new gaskets.

I'm wondering if there was something up with the first cam I put in, and it pitted or damaged the rollers on the lifters in that manner. I don't recall how many miles it had on it right now.

Thanks,
-marc

 

Everyone praises gm and stock replacement lifters so much. Yet, no one has solved the ls1 ticking problem. Ive personally changed out my lifters twice, with stock replacements, changed to shorter pushrods (.050, Then .100 shorter), changed the rocker arms. Both times when I pulled the lifters out, there was nothing wrong with them. You could put them in a vise and it still took them a few minutes to bleed down. Tore them apart and nada. Changed the oring out too. I am thinking as of now that the other cam wore in the lifter bores up to its lift and now you have more lift and part of the lifter bore is wore in more than the other, thus making the noise. Until someone figures it out, I guess we all will just have to live with it.

 

I did many of the same remedies you did, to no avail. Your lifter bore theory is very interesting. I wonder if the same thing can be applied to the plastic lifter guides. Any chance of hitting the top of the lifter guide? Just wondering...

 

Thanks guys...

It's strange, because I had it much more often with the .550 cam... and I only heard it two or three times briefly (and to a lesser degree) since the rocker install on Sunday, and I'm at slightly more lift now.

I think whatever that nasty knock was, is related to this. It probably wouldn't hurt me to do a compression check on everything.

I'd like to do heads this spring. If it happens, I'll definitely be replaceing lifters.

 

I dont know. I got the idea of an out of spec lifter bore from Kurt urban of w2w after describing my problems, stories and all.

 

Hey Marc, I have the exact same sound. I mean you described it perfectly. When you are off the gas it is really noticable. Are trucks are real close to being the same truck, my lift is 555/563. I just think it is either the springs or just the lifters. I know that I went from 7.350 pushrods to 7.325 to get the right preload on the new cam and got more noise. I had alittle too much preload before, now I am at 1 and 1/2 turns, this is what the rockers called for. I will find out with the new heads if it is the springs. They will have the Patriot springs.

 

Awesome Matt. (well, the heads, not for having the noise!).

I'm still entertaining head idea's for my truck - how soon do you think you'll get yours bought and installed?

 

This is the curse of the LS series of engines. I'd wish someone could actually pin point it instead of all the speculation.

What causes the sound? Is it inherent it's it's design? Is there NO way to get rid of it? What is it...someone please!!!

 

Perhaps it's due to having aluminum heads and an aluminum block. Noise carries much differently with aluminum and only the slightest valvetrain geometry from stock causes the noise to be amplified. Of course, and again, this is speculation.

 

I have the same exact noise. It has gotten louder in the last month or so. I even went so far as to insulate the hell our of the driver and passenger floorboards and behind the dash area, but when the windows are down and I'm at a drive-thru, it really does embarass me. I just put on some Yella Terras late last night. Hopefully they will help a little. I have new lifters sitting in the garage, but I'm waiting in hopes of getting some new heads before I go to all the trouble of pulling them.

 

I believe you all have touched on the problems. The XE type lobes + the roller rockers + the all aluminum contruction of the engine will all contribute to the louder ticking or "scissors" noise. On a SBC I noticed that a strong cam with roller rockers made considerably more noise than the stock setup. But when I changed the aluminum rocker covers to a stock steel design the noise actually quieted down.

We are also talking about some nice size cams here. We didn't hear this much noise with the SBC's back in the day because these cams were considered track cams and not very friendly on the street. ie. a tr224 back then seemed like a T-Rex. JMO.

 

I had the noise even with my stock LS6 cam but to a lesser degree. Now with the Comp XER it sounds like a collapsed lifter, up until 3500 rpm when the tick seems to blend in with all the other noises of the engine. If it's a product of design, I guess I can live with it. Doesn't hurt nothing, just anoying as hell!

 

I guess you have a point. But I also read all of the stories on here of people hearing ticks and other noises that come to find out that they do have a collapsed lifter or a rocker arm failure or a bent pushrod. I've checked everything but the lifters and found nothing, but there is still that tiny possibility that a lifter is having problems. I guess I just need to drive it until something breaks and then go forged. I just hate having an engine with 14500 miles that sounds like it's about to come apart.

 

Thanks for all the discussions guys.

I'm going to go through the rockers again to make sure they're properly adjusted. It hardly takes any time at all, so why not. I have my doubts, seeing as I was in "panic mode" at the time I snugged them down due to improperly preloading them the first time around, causing the motor not to start. I'll report back on this a few days after doing so... (yeah, I'm cringing too... make that "still cringing".)

When my noise is present, it's definitely MUCH quieter compared to what I had before. You can only hear it with the windows up and the radio off. It's not noticeable in a parking garage.

 

Its funny how we have all these sponsors on this site lurking, but not helping in situations like this.

 

I changed my lifters to the Comp 850-16, I have NO more of the familare LS1 ticking any more. It's alot quieter now.

 

No noise whatsoever, or just reduced? If all it takes is a set of good lifters to get rid of the noise then I'm in .

 

Lifter preload. If you don't have enough, you will have valve train noise. I've had three cams in my engine (counting the stock one) and have always had a queit valvetrain. I'm runnig Comp lifters, but I had no noise problems with the stock ones either.

 

I agree with the preload, when I had what I thought was too much the valvetrain was much quieter, I was about 1/2 turn more than the rockers called for and was worried about losing a lifter, but it was quiet. I think it might be the roller tip rockers. I might try the SLP 1.85s on the new heads.

Marc, a few weeks maybe more like 6 weeks on the heads, going for a TB stall first, I hope to get to the AWD dyno before the head swap, I am going with the TEAs. Brent has been a huge help.

 

I recently had the same noise after my head swap. I was running the 7.35 pr's(stock) with stock lifters. I was supposed to get milled heads, but the company forgot and I got 66cc heads. After putting it together I had that tick. I ended up switching to 7.4's to get the proper preload and it is very quiet. My friend with his 366 had the same noise in the begining too. He has new lifters and adj rockers. He had to adjust everything a couple of times, but even now it is quiet.
-matt