00camarossMV

I can't figure out if this sound is normal or not. Its like a high pitched metallic sound. Only does it at idle, goes away when revved up. For all I know this is normal for this cam. Any suggestions on what it could be would be very appreciated. I've listened to a lot of other asa cammed cars online and i don't hear this noise but then again its hard to tell sometimes with computer speakers. Car is a 2000 Camaro SS with stock ls1 lower end, stock 799 heads, GM ASA cam-226/236 .525/.525 110lsa, LS6 springs, LS6 intake,Comp cams trunnion upgrade, Brian Tooley slow leak rate lifters-.075 preload, ls6 oil pump, cloyes timing gear set, stock exhaust manifolds, custom y-pipe with cats, hooker muffler. For some reason I couldn't upload the video I took so I put it on Youtube. Thanks.

00camarossMV

Apparently the video did upload.

bottlefedbaby

Does the car have a tune?

00camarossMV

I have only tuned it somewhat in the idle region just to get it to idle ok. I have not driven it yet. The weather is still too nasty here in Michigan. I tune it myself with hptuners. I could post up my current tune tonight when i get home if you think it could be tune related.

poltergeist 02

iTrader: (65)

Your preload is set a little high. How did you measure your preload? If I were you I would back it down to .030"-.040".

bottlefedbaby

I'd pull timing back a degree or two just to see if thay changes the sound at all. But your preload could also have something to do with it.

00camarossMV

I've changed preload all around. .050,.075,.100. I used the comp cams checker. Doesn't make a difference at all. Idle timing is set at 24 degrees. To me it almost sounds like the valves pinging but like I said before I've never heard this noise on any other cammed car. Its driving me crazy.

00camarossMV

Any other suggestions would be much appreciated

bottlefedbaby

Do you know where exactly the sound is coming from?

00camarossMV

It sounds like its coming from the exhaust manifolds

bottlefedbaby

Man im really not sure... part of me wants to say detonation but I don't want you chasing your tail. I know a lot of those cars do make weird sounds after a cam swap. I don't want to tell you that its nothing though.

00camarossMV

Yeah I understand. Maybe I'll try one of those top engine cleaners just to see if the sound changes at all.

bottlefedbaby

How long has the car been sitting? Bad gas maybe?

00camarossMV

It's been sitting for months but I start it and let it run awhile at least once a week. I keep filling it up using a 5 gallon can with 93 when it gets a little low

bottlefedbaby

Im really lost maybe pull the valve covers and turn the motor over by hand and make sure everything has enough clearance

00camarossMV

I have already done that numerous times changing pushrods for different preloads

00camarossMV

I ran the car again tonight to get the raf dialed in. Afterwards I started to play with the vcm controls in hptuners. I moved the timing, afr and rpms all over the place and none of it made a difference with the noise. It does go away at 1500 rpms. The valvetrain is the quietest it has ever been under the hood, i dont hear the noise at all but under the car is a different story.

bottlefedbaby

Did the heads get milled? I've showed your video to a couple people and too many of them say that it is normal but I don't think so.. slim chance but maybe your valves and you pistons are getting to know each other too good? I could be wrong and this could be a normal sound but coming from the manifolds? I assume this doesn't go away once the car is warm? Scratch the valves meeting pistons that'd ger worse with rpm. Doea it sound like its every cylinder making this sound?

mchicia1

iTrader: (5)

Did you run the car with no belts yet. That's always the first step. If it stops, you know it's accessory related.

It sounds like a pulley to me or your harmonic balancer is wobbling causing the noise. I had that happen to my car.

RockinWs6

As bazaar as it sounds you may be hearing the valves closing against the seats. The headers amplify the sound.