When I turn my highbeams on, after about 30 seconds all of the lights begin to flicker.

It does it when im just sitting there or driving, so i kinda ruled out the loose wire theory.

Bad relay?

Help! I need high beams!

o BTW the low beams are fine

 

Are you using a underdrive pulley for the alternator???

 

I had this happen on my 71. It was the dimmer switch. FWIW

 

nope no under drive pulleys.

Replaced the dimmer switch a while ago.

Im stumped.

 

Pull and clean the terminals on the bulbs,and pull and clean the grounds at the lights,both front and rear this might help.