Nissan Repair: valve cover screws, 280z, valve cover

Question
I have a 1975 280z - I recently changed the gasket on the valve cover, but two of the screws don't tighten anymore.  One on them go in to the casting and the other one go in the casting but it comes out on the other side.  I was wondering how I can tighten them.  It will continue leakin oil if I don't tighten?
Thanks

Answer
Martin,

Try to use lock-tight.  But remember these are not supposed to be tight tight.  They are supposed to be a little tight.  

Tighter than a finger tight.

If lock-tight doesn't work, you will need to drill the holes out and re-tap it.

Tight tight tight tight

Keep tight

Darrel.