Replaced valve cover. Broke a bolt in process and stripped 3 holes. Helicoiled 2 of the holes. The bolts wont go down all the way in the helicoil. One of the helicoil holes. I drilled straight into the engine. For the bolt that broke off all I did was pour liquid silicone in the hole and around...

I have a couple holes stripped out on the head of my 2011 Chevy Cruze. Does anyone know the size of the helicoil that I will need to use the same bolts?