I just pulled my heads on my ls1 to drill and tap new header threads and i have just started it and it runs and idles fine but i have a valvetrain noise, a knocking sound. what could that be?? I installed everything in order as it was and cant think of what it is. Or does it make noise for the first while after starting? when i started it, i made the noise only on one side, but it got worse and is now on both sides after about 5 min of running. Any suggestions will help.

Thanks

 

How is the oil pressure? I know when I did my Crane rocker installation, it was noisy for about 5 minutes and then settled down.

Did everything go back in the same place?

Maybe you should pull a cover and verify your rockers are still tight.

 

Deffinately check the rockers. I'd suspect that first.

 

make sure a header is not leaking, some people have mistaken that for valvetrain noise