Vortec 454 vacuum leak/rough idle

[andy396]

Sorry, forgot to mention, dont use any kind of sealant on a base gasket.
It will swell up as it cures and, if ya follow the instructions amd wait 15, it will leave an air gap causing a vacuum leak.
Make sure the base of the throttle body and intake are very clean and flat. and bolt it down dry

I’ve had good success sparingly using ultra black rtv in the corners and around the coolant ports with no ill effects. Just pre-torque to a third to a half the final torque and come back after it sets with the final torque. Just don’t forget to do the final torque before putting it all back together.