The tech would have rather done a new motor if it was an option. They were backed up 3 weeks before getting to it. took 2 weeks to get done.
A big prime rib will continue to cook after you take it out of the oven, so for a final medium-rare temperature of 130 F you need to take it when it reads 120 F on your instant-read thermometer. Note that the U.S. Department of Agriculture recommends all beef cuts be cooked to an internal temperature of 145 F.
Seriously, they will take 4 hours (baby back ribs) to 5 hours (spare ribs). A good and reliable test is the bend test. Pick up a slab with a pair of tongs. If the ribs are ready, the slab will bow and the meat will slightly crack on the surface.