Hey guys, so I've been having the heads and cam on my Z06 for a while now and everything seems to be good with the exception of alot of valvetrain noise once the engine warms up. it wasent as bad as this when I initially started the car, using mobile 1 10W30 synthetic. Then I switched to 5W30 and thats when I started to notice the noise. im running 10w40 and the noise seems to be a little better but its still there.

the lifters are ls7 and the preload should be .087" due to the 7.350" pushrods im using. cam is 228/230 .571/.573 on 112 LSA.

What do you guys suggest i should do?

 

If the noise is that bothersome (some is normal) I would check the preload to determine more exactly what it is.

(Note: The last time I check Mobil1 5W-30 had a higher high-temp viscosity than Mobil1 10W-30.)

 

Need more info. What kind of heads?Milled?Gasket thickness?

 

Probably try and get used to it. Some if not most of what you might be hearing is perfectly normal for aftermarket cam lobes. You can try running a thicker oil at hot (40w) as that will help quiet down the lifters, but besides that as long as you have the right length pushrods and preload there's not much you can do without swapping the cam to something with softer ramp lobes.

 

Heads are TEA stage 2 LS6 milled to 62cc chambers with ls3 intake valves and ferrea exhaust valve. Gasket is stock GM MLS 3.9" bore head gasket. Springs are PSI 1511ML with titanium retainers. Rockers are stock with comp trunions. pushrods are comp 7.350" hardened but stock diameter.

 

This may be the case. It is my first cam car ever so I may just be paranoid. Ill see if I can post a vid and you guys can let me know if its normal.

I have also heard that mobile 1 0W40 european formula is pretty good too, but I need to look more into that before I go for it... currently running mobile 1 10w40 high mileage synthetic.

 

That is quite a bit of preload for ls7 lifters. .060 is all we recommend really. Why would you run a thicker oil as a bandaid? It can change the way the engine dissipates heat as well.
If you installed the cam just one or two teeth advanced in error (it happens often) it can be as much as 10* advanced or retard really, which can cause almost the same noise as valvetrain noise. Indeed it really is but only on the "valve" part.
I would back off on the preload. Those are comp xtreme RPM lobes in case anyone wanted to know.

 

I had that cam at one time. It's ground on XE lobes. When I switched to LS7 lifters I gained some noise.

 

If he is worried about noise he should run closer to .100" preload. The LS7 lifter plunger has close to .200" of total travel.

 

I have sure not heard of that being in the normal range. .040-.080 is the max I have heard that is normally ran. I would be worried about other issues running that much preload in an LS7 lifter.

I have personally ran .050-.060 and the only noise I get is the light sewing machine noise. Nothing noticeable.

 

While I don't necessarily agree...GM sets up the COPO @.080"-.100" preload with a .200" travel part.

 

i am not sure what they use in the COPO so I cannot say on that either.

 

I could achieve this if I went with a 7.325" pushrod. that would put me at .062" preload.

 

I would rather measure than just get the pr set blindly. But it looks like they would get you on the window on paper.

 

LS6 heads are right at 64cc. to get them to 62 about .014 should have been removed.

If you are running a stock 3.90 gasket that should be around .051 depending if you went with graphite or MLS.

Most aftermarket cam's are cut on a smaller base circle which can require a longer push rod.

How are you determining your preload? If anything it seem's you don't have a long enough push rod.

It has been a long day though, maybe I am missing something.

J

 

I have measured many gm gaskets at .053. The math doesnt always work right either due to many reasons. One of which is deck height.

 

7.350" is a pretty short pushrod for no more than you have milled. You can throw some 7.375s or 7.40s in there to see if it quiets down for you.

 

Again I would measure instead of throwing random sizes in.
7702-1 is the PN I use most often.

 

I agree he should measure. But, I disagree that there is one particular narrow range that is "proper" with the factory GM lifters. Over time, I think the evidence shows that people have found quieter results with a wide range of preloads.

I think the most common that are heard are in-between .060"-.100", but I have seen people go as far as .120" and a little as .020" to find what they feel is the quietest pre-load.

My LQ9 came from the factory with over .100" of preload. Recently, a well known engine builder was on here recently reporting that he has successful used various pre-loads on the same engine successfully in order to get quieter valvetrain. So, I just don't think that narrow range that you suggested holds true for all engines.

 

I'm in the .060-.080" range and the valvetrain is pretty quiet.

I vote for checking your preload and not guessing. At least then you can pop off the valve covers and inspect the rocker arms and trunions. When I had a tick develop, it turned out to be the trunions coming apart.