Prime Rib Time

jimi1234 · December 2012

I'm doing an 8 lb prime rib for Christmas. I'll be slow roasting it at 250 deg. What is a general rule of thumb for time for medium rare? 25 - 30 minutes per pound? I'll be cooking to temp, but just want a rough estimate so I can time when to put it on.

Cheers

Jimi1234

nolaegghead · December 2012

That's about right if you cook around 250. Monitor the internal temp.

jimi1234 · December 2012

Great. Thanks Nola.

Skiddymarker · December 2012

I think you will be over temp at 25-30 minutes a pound at 250. I'm thinking you will be ready to serve in 2-1/2 to 3 hours max. The good news is, if you finish at 125-130, it will keep in a warm oven for an hour or two with no issue.

I usually cook at 225, and it is always done in under 2-1/2 hours before a sear.

@Nolaegghead - for an 8#, at 25/#, time is 3 hours 20 minutes, at 30/#, time is about 4 hours. I think at 4 hours at 250, it will be overdone.... Your thoughts?

lousubcap · December 2012

Just estimate on the short side and go from there-afterall, 5 mins/# and 7#'s is...you can do the math. You are better off extending the feed-me time by a few minutes than trying to choke it down on the back end especially with prime rib. YMMV-

Skiddymarker · December 2012

Standing rib is one of those roasts that can be longer than it is thick. My experience, including working at a steak house years ago, was that it all cooks in very close to the same time, 2 ribs, 4 ribs, six ribs - very close to the same time to finish at the same cook temp. The thickness of the roast is the same, regardless of the number of ribs, assuming 2 minimum.

With a slow cook it is easier to catch the roast to avoid overcooking. Good luck!

nolaegghead · December 2012

An almost 4.7 pounder took about 2.5 hours for me yesterday at 270 (I had a leaky stoker fan and couldn't get it lower than that). I'm gonna guess about 3-4 hours, depends on shape, at 250. Mine was from the small side. If it's from the big side or a big rack, maybe even longer. I'm sure there's some surface area to mass ratio that's not linear to weight based on shape - (extremes are ball shaped and infinitely long thin tube). The tube will cook faster. Bigger roast is more tube than ball. I'm semi wasted right now. Hot tubed left over rib roast with potatoes, gravy and a salad (and horse sauce). Awesome.

Gandy Dancer · December 2012

Thirdeye' Cookin' Site has some good reading Prime Rib.

Skiddymarker · December 2012

NOLA - Understand completely, sleep sweat prince!

I did a five rib, <9.5# two weeks ago, 3 hours start to finish including reverse sear. Like you say the tube cooks faster. The time per pound formula does not work with standing rib.

Just saying.....

nolaegghead · December 2012

Skiddymarker said:

NOLA - Understand completely, sleep sweat prince!
I did a five rib, <9.5# two weeks ago, 3 hours start to finish including reverse sear. Like you say the tube cooks faster. The time per pound formula does not work with standing rib.
Just saying.....

I dig brother. You could probably put together (and by "you" I mean someone who isn't totally wasted like me right now) a table or guide or program based on 5 parameters to accurately predict the cooking time at temp. Those parameters would be weight, internal temp, cooking temp, length and average diameter. I further postulate you could make this with very few empirical studies and using basic math to extrapolate the data. Finally, this is fodder for someone who wants to make an app for a smart phone, tab or computer to calculate the desired results very accurately (assuming all the thermometers were accurate). And a PS - if I can think of it wasted, and it makes sense, it's probably already been done. </end lengthy paragraph> ;)

Skiddymarker · December 2012

Here is a great page, (mostly because Meathead agrees with everything I've learned and been taught). It is a little long, but lots of great information on doing standing ribs and other beef roasts.

http://amazingribs.com/recipes/beef/prime_rib_roast.html

Griffin · December 2012

Just got off the phone with my Mom and she bought the prime rib. So any thoughts on how long a 13.89lber is gonna take at 250 with a reverse sear? At 20-25 minutes a lb (if that's right), I'm getting a range of 4hrs 37min to 5hr47min. Does that sound about right? I really don't want to screw this up and let down the family.

nolaegghead · December 2012

Griff - give yourself 6 hours. Cook until it's about 125, pull it and it'll keep, ready to serve, for hours in a warming oven. If it's ready after 4 hours, no problem, throw in warming oven. It'll definitely be ready on time.

nolaegghead · December 2012

Skiddymarker said:

Here is a great page, (mostly because Meathead agrees with everything I've learned and been taught). It is a little long, but lots of great information on doing standing ribs and other beef roasts.

http://amazingribs.com/recipes/beef/prime_rib_roast.html

That's pretty good article, skiddy - I figured out one thing on my own that i jus read on there - don't use the baking pan under a v-rack. The bottom wasn't cooking as fast as I wanted.

Skiddymarker · December 2012

@Griffin, Griff - I agree with Nola, that it will keep and to avoid being late, you might want to finish it early and hold.

Another post someone said that his butcher found standing ribs seemed a bit larger this year, at 14#, I'm guessing your Mom's rib roast is a 5 or 6 rib cut. As @Little_Steven said, it is the thickness of the cut, not the total weight that determines how long it takes at a specific temp. In other words a 4#er will finish in almost the same time as a 14#er. I'm betting your roast will be done in 3 hours, with a ready to serve sear finished in 3-1/2 hours, if you wanted. However as Nola says, it will keep in a warm oven without overcooking.

If you cook at 250 for 4 hours, I think the internal will be at about 150, to me that's overdone.

I posted this link above - if you have the time, check it out.

http://amazingribs.com/recipes/beef/prime_rib_roast.html

Let us know after your cook how it went.

Skiddymarker · December 2012

nolaegghead said:

Skiddymarker said:

Here is a great page, (mostly because Meathead agrees with everything I've learned and been taught). It is a little long, but lots of great information on doing standing ribs and other beef roasts.

http://amazingribs.com/recipes/beef/prime_rib_roast.html

That's pretty good article, skiddy - I figured out one thing on my own that i jus read on there - don't use the baking pan under a v-rack. The bottom wasn't cooking as fast as I wanted.

Yeah, I would love it sat it was my superior intelligence and good planning, but it has always been s**t luck, I have always done mine indirect on the grid with a drip pan raised off the setter under the grid.

nolaegghead · December 2012

Yeah, I revise my time estimate. It might be up to temp a lot faster, than 4 hours - depends on the diameter and your cook time. If it's the same diameter as mine, it took 2.5 hours. (mine from the small side). Anyway, maybe give yourself 4 hours would be fine too, and you still might have to keep in the warming oven.

Skiddymarker · December 2012

@Griffin, here is another thread from a few days ago, just found it....Thanks @rustypotts

His 12#, no bone, was done in 2-1/2......

http://eggheadforum.com/discussion/comment/1265110/#Comment_1265110

Griffin · December 2012

it's a 5 bone today.thanks for the replies.

jimi1234 · December 2012

My oven will be in use for other things. If my roast is done early, is there another way to hold it until it's time to serve?

Skiddymarker · December 2012

FTC, it will hold for maybe two hours (That's the longest I've held - somebody may have gone longer)

Wrap well in foil, then in some towels, then into a pre-warmed cooler. If you had a crispy crust, it will suffer without dry heat..

lousubcap · December 2012

Great info above-and given the size of your roast you can safely FTC (lots of towels and a warm cooler) for 4-6 hours. Some have gone 8-12 hours, no problem. So, if you can't get within that finish window, time to recalibrate your watch :)>-

jimi1234 · December 2012

Will there be any additional rise in temperature with FTC compared to if it finishes on time and does a normal rest before carving? That is, should I take it off sooner than I would if I am on target for time?

lousubcap · December 2012

You can expect a 5-8*F bump with the FTC-but it's not much more than the tent/rest rise you would get before slicing w/o the FTC-YMMV.

Skiddymarker · December 2012

If you are cooking at 250 and the internal is 120ish, you can see a rise to 125-130ish due to the FTC. so yes, between 5 and 10 rise is expected. My experience has usually been on the 5 side, but it could be more.

You can FTC it at say 120, no sear, let your egg idle until about 20-30 minutes or so before you want to carve. Heat the egg to hot, 550-600, pull the roast from the FTC, use the juice i the foil to help your gravy/au jus, and then sear the roast to crisp the crust. Remember the sear will cook the outside 1/2"-3/4" a little more than the inside, but it will all be good.

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