03 cobra noise normal or f&$%ed

[scalloped91]

After finally finishing my whipple 03 cobra motor rebuild, I have acquired a rather nasty knocking noise. The noise has been there since start up.The noise sounds like I have solid lifter cam but I don't. The top end is all stock parts. The lower end is all stock except the pistons; the pistons are CP bored 30 over. The noise is very loud and comes from the back of the motor near the bellhousing. I thought the noise might be a clutch issue because I heard spec clutches are very prone to making noise. I removed the clutch and tranny and the noise is still there. At this point, I am just hoping some one can tell me this is a normal noise and it will go away. I know that is very unlikely. If it is not going to go away, what is causing the noise. I have posted a YouTube link that will let you hear the noise very clearly. If you are familiar with this noise, please help me.
Thanks in advance.

https://www.youtube.com/watch?v=q7ak1Xl2IQM&feature=youtube_gdata_player

 

[nightsun]

What you find out?

 

[Scotty B]

Not normal. Hard to tell from the video but, sounds like metal to metal. A friend of mines car had a similair noise. We thought it was a lifter bleeding down. pulled the cam covers and all the lifters were solid. chain tensioners were also tight. Dropped the pan and checked all the rod bearings (had to lower the K member, PITA). they were fine. finally, found #5 piston was loose in the bore. It had scuffed and started slapping. Not saying thats what going on with yours. Just illustating how we tracked it down. It doesnt sound like an exhaust leak in the video. I would make sure tho before going to that extreme. You could also remove the blower belt and start it up. This will rule out any supercharger issues if the noise is still there. GL

 

[ColorMatched]

Who built the motor?

 

[scalloped91]

Who built the motor?

I posted this thread for my old man. He built the motor. The noise is weird as hell. The noise sounds like a upper end issue but it isn't. We have pulled the exhaust off, the tyranny and even the clutch, and the noise is still there. The only thing that hasn't been pulled is the flywheel and starter. One person on the internet has a 4.6 with the same knock. The guy did a 2v to 4v swap and the only parts he kept was the flywheel and starter. I know it is a small chance in hell it might be that but he's going to buy another flywheel and swap them out. He figures it has to be worth a try over pulling the damned motor back out.

 

[nightsun]

im in the same boat as you. However, as Scotty B found on his freinds car, I suspect I will find the same thing on mine. During the tuning process, I ran my car lean (12.9-13.2) at 17lbs. Now I think one or more of my brand new > 100 mile diamond pistons is fubar along with the bore. Compression was perfect, oil had no metal in it...Im gonna use a sea snake to peak in the bore tonight to see what I find. Good luck with yours.

 

[Midnight_Cobra]

I've had two problems with this. If you search my profile you can see the two threads I made. That actually fixed my problem.

Then yesterday like 5 ft from where I was going to park my car, I heard a loud bang and it starting ticking like crazy, but the motor seems strong, and it didn't rise with RPM. Low and behold my fan cracked and was griding on the broken fan blade.

Keep your head up man, hopefully it was something stupid like mine was.