I have the same noise coming from the driver's side that seems like coming from under the car. Yes, I have LG pros. Stethescope on the valve train doesn't find the sound. I'm also thinking leaky exhaust. Let me know what you find.

 

I think it's the headers. My trans am and corvette both had that same sound after i put the headers on them.

 

OK, things I've checked/done so far:

- Checked all the spark plugs, none loose

- Added Eastwoods ZDDP to the motor oil (Mobile 1)

Still no help, it gets a little quieter when the engine warms up. Very clattery at low speed like when going thru a parking lot even when engine hot. The car shows no performance degradation what so ever and does not smoke. Oil level has not dropped since I got it changed a couple months ago, but that was about the time I had the LT's installed. I seem to have noticed the engine noise since then and I do not know what the previous owner had in it.

Thinking of trying another motor oil. Read that some guys like the Castrol Edge Ti full synthetic but I'm skeptical that this will help.

What is the "trunion upgrade"? I have not gone as far as pulling the valve covers.

 

I spoke to several corvette mechanics who do not recommend the trunnion upgrade. Many said they have seen many more rocker failures with the trunnion "upgrade" than they have with the stock rockers. I found this very alarming because I was nearly ready to order the trunnion upgrade. Could be bad info, but I trust those mechanics and they have good reputations.

I couldn't ever source my noise, at this point I think it is probably just something to do with exhaust. I got a stethoscope back on my engine, and all the headers (right out of the heads) sounded perfect and near identical. Also my crankcase is nearly dead silent so its nothing in there. The noise I was hearing was down low on the headers near the collector, so I'm thinking its exhaust related, possibly something at the ball joint, or maybe a bad header gasket that is leaking exhaust down below.

Either was I was kind of looking for an excuse to upgrade, so I called Complete Street Performance and I ordered their Heads/Cam package along with a set of Lunati Link-bar Street Series hydraulic lifters.

Finally gonna have a much more robust top end with a good bit more power. The owner of Complete Street, Andrew, literally spent hours on the phone with me and answering every question that came to mind. Being a studying engineer, I asked a ridiculous number of questions. Looking forward to when the install happens after parts arrive. Will post with updates.

 

If the rockers are fine and you don't have broken valve spring, then it is probably because headers do not dampen sound like a cast iron manifold. You always hear more valve train noise with headers, and if you added a bigger cam it will make more valve train noise.

 

THAT,,,,,,,,,,,,, Is EXACTLY what I was going to type! YES,, you will hear more valve noise with headers. Just a fact of header life.

Trunion Upgrade. Your rockers ride on very tiny roller bearings. The rockers have been known to pop the cover off and puke out all the little roller bearings.

Comp Cams sells a trunion kit that eliminates that issue:

http://www.summitracing.com/parts/cca-13702-kit

Bill

 

Same issue here. Installed LG Pros. Sound seems to be coming from under the drivers side after checking with stethescope. I checked my plugs and header bolts. All good. Since there's no degradation of power I'm going to live with it.
I switched to Pennzoil Platinum and didn't make a difference.

 

Yeah a good buddy of mine who builds supras and vettes also said I'm just hearing extra noise through the headers which I wasn't previously used to. Not too worried about it anymore; just looking forward to getting the top end built and cammed. That way, even if it makes more noise, with the top end rebuilt with dual springs, lunati link bar lifters, new push-rods etc, I can sleep soundly knowing its solid.