do not overtighten any bolts that go into the head on a focus or any othercar with and aluminum head.
The Focus valve cover is supposed to torqued to about 13 to 14 foot pounds(can't remember the exact spec). Any tighter and you will strip the threads on the head before damaging the bolts.
The bolts are usually steel and a harder material than the aluminum head.
Fixing a stripped bolt hole can be verry costly. I don't know what happeded but 4 bolt holes in a non-focus aluminum head became stripped and minus the cost of a new head gasket and other gaskets, the 4 bolt hole repairs costed $70.
If you have a duratec engine get a book on it. The entire block and head are aluminum and torque specks are critical.
Don't learn the expensive way. Let someone like me bight the bullet and tell you what not to do..
The wholes needed to be a specific size for mechanical parts to fit properly and function properly. Holes needed to be helicoiled to keep the proper size.
And the same goes if you strip a valve cover bolt hole. Sure you could drill the whole bigger but than you need to drill the valve cover also and than hope to find a long enought bolt to fit.
