2G Slight rattle at cruising speed?

[LilRedSpyder]

So the car runs great aside from the slight lil rattle when I’m at cruising speed in 4th or 5th gear. Also it doesn’t do it steadily, it’s only when the throttle/rpm is in one specific spot. If i accelerate even the slightest or lift off the rattle stops rather quickly. I’m talking a very lil change up or down in rpm and it’s gone.

The bottom end was recently rebuilt and everything torqued to correct specs and patterns. Anyone have any idea what the issue could possibly be? The head was refreshed with BC springs and retainers, new valve guides, seals, upgraded HLAs, etc with maybe 5k miles max on the head. I’m running black box ecu and tactrix. Any feedback is much appreciated!

 

[steve]

What does it sound like and where is it coming from? Those details could be important.

 

[LilRedSpyder]

It sounds like it could be in the top end. It’s more of a faster sounding chatter than a spun bearing. I definitely can pick those out with no problem... but it puzzles the **** outta me due to how quickly it goes away with a lil rpm change either direction.

 

[steve]

So it's more of something resonating than a knock. Any chance its an exhaust heatshield. It only does it when your off boost, cruising?

 

[LilRedSpyder]

Correct. And no heat shields in the vicinity. I recently swapped cams and have decided that I’m gonna swap them back. Gonna also go ahead and clean my lifters and rockers good with diesel before I put em back in. I’m thinking it may be something in that area bc it wasn’t doing this before swapping cams.