You can pass the NCLEX even if you run out of time. The scoring method for this is explained in the NCLEX Candidate's Bulletin. You are evaluated based on your performance on the last 60 questions. You will pass NCLEX if your competence level remained above the passing standard for the last 60 questions. This doesn't mean you had to answer all 60 questions correctly, you just had to have your competence level be above the passing standard for these questions.
The detailed explanation is found here:
http://www.ncsbn.org/testing/candidates_post_test.asp
What is more important is that you are able to remain as stress free as possible and not worry about running out of time. Concern yourself with taking the time that you need to read the questions and responses so that you can select the best answer. You need to do what is appropriate for you to be able to answer the questions correctly so that you can get to the passing standard and remain above should you run out of time. Rushing and trying to "beat the clock" will cause you to make more errors and this could hurt you far more than running out of time.