i was changing the omp lines on my 86 na when the black vac line broke. i read in another thread that they only pull atmosphere vacume so i was wondering do i really need these vac lines or do i just need to protect the omp injectors from getting any debris in them?

 

Yes, you need them to help force oil through the injectors. If your vacuum lines are brittle enough to break, you probably need to go through and replace ALL of them. Bulk vacuum hose is cheap.