I recently changed out my cam for a second time.. After I started the motor, a new noise appeared. What it sounds like is a rocker being loose and the pushrod is tapping it (I hope that makes sense). I don't think that is the actual problem, but that is the best example I could think of. At the top of the motor you can hear it, but when I listen at the driver's side of the block, it is very very noticeable. Sometimes when it is cold (like 20f), it won't make noise right away until it warms up. Some mods: ls1 04 gto, cam is around 228/232 at .600 or so, afr 205 heads milled .05, 7.4 pushrods, and tuned. Oh, and I'm using mobil 1 15w50 synthetic oil. Any suggestions? Thanks.

 

Sounding like a sewing machine after a cam change is normal.

 

probably some valvetrain noise wich is to be expected on a cam swap.

 

LS1's are know for the tappety tap. Each motor is different though. Do you still have stock rockers? There is not too much to check with stock rockers, as each is torqued to 22ft lbs. I usually roll the motor as i tighten these just to make sure. Sometimes changing rockers can help. Double check your exhaust bolts for tightness just in case. Other than being very annoying, it is fairly normal.

 

That seems like a lot to mill (.050) and still be using 7.4's? Did you happen to check P/V clearance? And last question are you also using a thinner head gasket?