Just got my green card. Can I visit to Nepal for more than six months? I know I need special permission for a year of stay but what about say 8 months.
Thanks

Anything beyond 6 months will jeopardize your permanent resident status and you need reentry permit. Check the USCIS webpage. They have all the information regarding your query.

thanks

When did you come to US? Have you stayed in US more than anywhere else in last 5 years?
In that case you can apply for I-131 (please double check on exact form) showing proofs that you intend to come back to US. I-131 will be valid for upto 2 years (1 year if you have been in US less than say 3 years) and will help you get back, but it is NOT A GUARANTEE that you will be allowed back.

So, if you don't want to jeopardize anything, don't stay for more than 6 months. If you have to, apply for I-131 and hope everything goes well.

You don't need reentry permit if you are planning to return back in 8 months. Only if you plan to return back after 1 year, you'll need a reentry permit. Whether you come back in 8-9 months without a return permit or come back after a year with a return permit, you will be subjected to similar type of questioning about what was the reason for travel for that long, are you maintaining your residency in US and bla bla bla....
As long as you have a good reason to stay out of US for that long (temporarily), you are fine.