I have a 2001 WS6 with a built 346 and ETP heads. Between the heads and motor are Cometic gaskets held down by ARP bolts. This just started, but when I spray the 150 kit, water comes out of the radiator overflow. I am pulling 5 degrees of timing out when I spray. Any help with a diagnosis? I do not want to tear into this motor.

 

The head bolts stretched. Our engine builder told us the ARP bolts on an LS1 are not strong enough for nitrous applications. He recommended ARP studs.

 

It's either that or a leaking head gasket.

 

there was some guy on here had a bad radiator cap with the same problem. just something to try before pulling the motor for studs. good luck!

 

mine is doing the same thing(cometics and arp bolts). before i used the arp bolts i called them and they said they would be fine for 150 or less? guess not. i had mine re-torqued and will try it one more time(i'm only on a 100 shot) it runs just fine n/a doesnt push out a drop??

 

I would use arp studs and stretch them 180 degrees.

 

I can't drive 30 miles NA w/o that happening??? Car overheats and she blows out the overflow. Did oil analysis, its fine. think it's the bolts?

 

When we took the heads off, the ARP bolts were loose. Some were a little more than hand tight. I KNOW for a fact these bolts were torqued correctly because I was doing it.

With the new ARP studs you dont have to pull the engine to install them. They can be installed with an allen wrench. The only one we had a problem with was the last stud on the passenger side. We took out the motor mount bolt and jacked the engine a little. It slid right in.

I also think the engine builder said the Cometic gaskets we used were not very good for nitrous. They showed no sign of blowing.

 

Did you re-torque after break in?