A buddy of mine has Ls1 thats the first problem, just kidding --- He just put on a underdrive pulley and at 5500 rpm it noses over floats valves no power. he has up graded the alternator. Everything was fine until the underdrive pulley would pull all the way up to 6000 rpm Any ideas

 

Why do you think it is valve float? Also try changing back to the orig. pulley that way you make sure it is not caused by somthing else. That would be my first step. Also try posting this on LS1tech.com you will get alot more LS1 guys looking at it over there.

 

He has tries to post else where but no one seems to know. Just giving it a shot over here thats all. Do you have any??????????

 

Yes try puting the stock pulley back on and see if the problem is the same, then come back to me and I will see what I can find out for you.

 

don't think it's pulley related unless it's drive a cam which it isn't......he'll need some new valve springs now

 

I just talked to my buddy and he said when he puts the clutch in it will go to 6000 rpm with no problem untlil he puts a load on it then the problem occurs.