1FastBrick

iTrader: (17)

Are the exhaust manifold bolts all tight? None broken off?

Choda

iTrader: (1)

Kinda a pain but pull the y pipe off and fire it up.

AKlowriderZ71

iTrader: (22)

Doesn't sound rpm related at all. Just a random loud rattle. Bang on hose cats when it's cold, I bet they rattle. I've heard this a hundred times.

black00chev

iTrader: (2)

You cant tell in the video, but it does rattle louder when I give it just a little gas. like 5%. Listen at :15 and :25, that's when I revved it just slightly with my hand on the pedal.

Ill check the cats again right now.

Manifold bolts SHOULD all be good, they are all new. Any that were broken were extracted and repaired when the heads came off. Never had this noise BEFORE the cam/lifter swap was done.

AKlowriderZ71

iTrader: (22)

Yes, it changed because the velocity of the exhaust changed. But the rattle does not match engine speed at all.

black04

iTrader: (15)

Definitely sounds like broken up cats too me. I had a similar issue. I don't know why it would be related to cold.

black00chev

iTrader: (2)

Yea I agree with both of ya. Ive heard a few busted cats and it sounds similar but confuses me that I don't hear them rattle when I knock on them with something.

On a side note, I guess this could just be my sign to go ahead and get an ORY made like I was thinking about so I can let my cam sign a little louder lol.

AKlowriderZ71

iTrader: (22)

Or just put that turbo kit on!!

black00chev

iTrader: (2)

haha yea no kiddin! This is and the last few issues during the cam swap has me ready to stop going any further with the build and save my turbo stuff for another project.

silver-mod-o

iTrader: (15)

From the sound of that vid the cats did you a favor and gutted themselves!!

Get rid of those things. I've never had them on a truck with over 100K but they do seem to be a problem with high miles, worse on modded engines.

I saw a truck one time run a week after a cam swap with cats and they broke up after that. I'm assuming they didn't like the increased pulsation in the exhaust stream and gave up.

-either way, get rid of those things and rule out a problem and it'll breathe better anyway.