Ahh I didn't see the notice that this was replied to.
That sounds like an excellent idea (blasting after resting).
I'm making another tonight; I will try that!
Thank you so much for sharing your wisdom. It really has given me so much more confidence in roast making.
:)

Thank you nonsticksteel, I was looking for a way that allowed me to keep the oven on, since the gas stove has a lot of places for heat to escape, so I could use the method mentioned.

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Reporting back results on what I ultimately did:

4.2lb spoon roast (about 4 inches tall in the middle).

- roast left uncovered in fridge overnight
- taken out of fridge, patted dry, rubbed with olive oil, paprika (both smokey hot and mild varieties), italian herb blend, fresh ground pepper, and lightly sprinkled with kosher salt
- then left to come to room temp sitting in a rack in the roasting pan for 1 hr
- 30 mins before cooking, preheated to 250 and allowed to heat for half hour while meat continued its coming to room temp
- roast in oven, temp turned down to 170
- checked internal temp periodically, starting at 3 hrs
- it was ready to come out at 4hrs 35 mins
- broiled at 500 for about 5 to 10 mins to crisp fat (this one had fat)
- out of oven and tented to rest 45 mins in roasting pan

It worked like a charm, not quite rare, but had the right texture, being amazingly tender (my fella said, like buttah), so it didn't matter.
I was discombobulated to find my meat thermometer's lowest temp was 140, so I had to try to guess at the temp.

If it had gone over 145 it would've been turned into chili or cottage pie tomorrow and the pizza guy would've been summoned, tonight.

Luckily, it was perfect and definitely "having company" worthy, for the future.

Hi fourunder,
I've been doing some research and I really want to try low heat. I came across some of your comments and it sounds like you have some experience in what I am hoping to do.

I'm having a dilly of a time finding a per lb at 170F estimate.

I have a tied up spoon roast (apparently, also known as top butt sirloin) and I have been searching and searching and having a difficult time determining just a guesstimate of expected cooking time.

I mean to test the internal temp using a thermometer, but I'd like to have just an idea of when to start the cooking.

I would like it to cook as slowly as possible.

I want to try cooking at my gas oven's lowest setting 170F (I've recently moved in, so I don't know my oven very well. I a not familiar with its quirks yet, but I know the minimum is 170).

I have all day to cook it, but I doubt something this small will take all day.

Goal is for a nice even rare with a thin grey edge and an outside crust..
I absolutely do not want the temp to ever go over 145. I much prefer rare, and I will be sad if it hits medium.

Based on many things you've said, and things I've read elsewhere,
- I'll sear it first, because it is smallish,
- then place it in a 250F oven and
- reduce the heat to 170F.
- I plan to remove it at internal temp of 125 and
- let it rest maybe 30-45 mins (whilst I am making the sides)
- I don't want the roast ready to be plated before 5pm, nor do I want to find myself tapping my foot at the oven at 11 oc'oclock at night.

Roast is 4.2lb spoon roast (about 4 inches tall in the middle).

From reading way too many articles, I don't know if I should expect 3 or 4 hours or even 8 hours in the oven.

My guess is about 4 hours in the oven? Maybe?
Do you have an educated guess, you can share?