If your grill is large enough, has a cover, and can hold a relatively constant temperature, you can certainly roast in it. It's something I do fairly frequently and used to do a lot more. Assuming you have the sort of gas grill most people do, it's very helpufl if it's both large enough and with the burners arranged in such a way that the roast can sit in the chamber without sitting directly over a burner. You can Micky Mouse that somewhat by using two (to make a double layer) disposable aluminum roasting pans to hold the roast and putting it wherever. With just about any other cut you'd need to use a rack in the pan as well, but the rib bones are a built in rack. So, there you go.
You can, if you like, sear the meat briefly over direct heat, but that's really unnecessary. In any case, you'll want to go the rest of the way over indirect heat -- hence the need for a large enough grill to get the roast away from the coals. You'll also probably want to turn the roast a few times during the cook to make sure each side and end is evenly cooked.
Depending on whether your grill is gas or charcoal, long or short, and oblong or kettle shaped, there may be a few worthwhile tricks. Tell me more about your cooker, and I'll tell you more.
No matter what you use, the first rule of long cooks is
NO PEEKING. As the roast cooks it gives off moisture which humidifies the hot air inside the covered grill. After the air absorbs as much moisture as it can, it stops stripping it from the roast. But every time you open the grill, the hot, moist air flees and is replaced by cold, dry air (no matter how humid the weather, cool air can't hold as much moisture as hot). So, no matter how tempting it is to check on the progress,
NO PEEKING.
Very few grills are supplied with a thermometer which is worth a darn. I strongly suggest buying a Maverick ET-73 RediChek Remote Smoker Thermometer. It has two probes, one for chamber temperature, and one for the meat's internal temperature. It's not cheap at around $40, but if you do much barbecuing it will change your life for the better. Incredibly worth it.
You might want to run a little smoke during the first half or so of your cook. Consider it a worthwhile option. Even if you don't use smoke and/or charcoal, your roast will taste wonderfully different than one cooked in an indoor oven. Speaking of smoke, a dedicated "smoker" is designed to cook indirect at steady temperatures. If you're thinking about getting one, now might be the time for an early Christmas present. But please don't buy one without talking to someone who knows the lay of the land as many lower priced smokers -- especially the Brinkmann Gourmet series (aka "ECB," for "el cheapo Brinkmann") -- can be very difficult to use, especially at first.
There's good advice in this thread about the chine, feather bones and fat cap -- you want to do as much prep as possible before roasting. As to seasoning, you can use simple salt and pepper, your "usual," or more of a barbecue style dry or wet rub. Don't worry, you won't have to do any "mopping" (which is what barbecuers call basting).
A simple
beef jus is very nice for a sauce, but there are a lot of other possibilities which you may wish to investigate depending on your level of ambition and tolerance for complication. The one thing I'd stay away from for a rib roast is the sort of tomato based "barbecue sauce" we all associate with barbecue.
Time/temp/lb cooking timetables break down once a roast is longer than it's wide. In the case of bone-in rib that's usually about 8lbs. No matter in your case, because you're certainly past it. Your roast will go somewhat faster than the timetables suggest. Also, cooking large cuts at lowish temperatures makes prediction even more difficult.
Fortunately, you can hold a cooked standing rib for four hours at serving temperature using nothing more than an insulated chest (a large Igloo will do nicely) some crumpled newspaper and cling wrap. In fact, the long rest is actually beneficial. That final flexibility makes the whole process a lot more fun.
Feel free to ask lots of questions. While there are a lot of little things which can make a big difference, they and the whole process are simple enough to nail it on the first time.
BDL
