How much Butt should I smoke?

My guess would be 8, but others will be along with better knowledge of it for you!

I'm thinking a total of 26.6 lb for 40 people. Thats cooking 2/3 of a pound per person and yeilding 1/4 pound per person, which is a decent serving when combined with a bun, slaw, tater salad and beans.

Now to do all that with your rig may require some pre-smoking and freezing. Does the church have a kitchen you can use?

Dog, I do a lot of multiple Butt Smokes. You said you expect 30 to 40 people . I would say plan a little big , figure for 1/2lb. per person (this covers the double/triple dippers ) and you'll still have some for a doggie bag or two... So 40X8=32lb.(you'll lose some to the Smoke Gods , 1/3 so IMHO , I would get 40lb. or so. Make it ahead of time and use Roasters to hold (after a boil in Vac-bags to 165°).

 if you have the room do it all at once , but be "Patient". Don't jack-up the heat during the "STALL" and leave the lid shut as much as possible and this is how they will look. Cook @ 225° (+/- 15°) until they reach 200° to 210°

 Not to worry, they will be tender (even if you go for the "Bark" and Smoke  without wrapping.) Maple or Hickory is a good Smoke.

You don't have a Vac-Pak , ask a friend over for drinks and use his - bribe too

Have fun and...

You shouldn't have any problem fitting 4 butts on a char-griller - don't forget your top rack

I usually plan on more than needed. I find that you usually end up with more people then planned. To help me with my padding of amounts I usually plan on a 50% yield on the pulled pork. I must add this, i usually use shoulders not butts, they are cheaper around here. I see above that some figure more loss during the cook. It does not hurt to fill the smoker if you have room

I figure on 4oz per person of finished product if there are sides.

So here is my math I would use...

40 people x 4oz = 160oz (10#) total needed, with a 50% yield I would start with 20# of raw product minimum.

If the butts are not too big you should be able to get at least 4-5 on the lower grate. If you have enough air flow you can use the warming rack for another couple.

I have done cooks for 200 people on my old char Griller. I staggered my smokes. I would smoke to an IT of 160ish then do the foil part in the oven and start another round in the smoker. As the pork in the oven got to the desired temp I pulled, bagged and chilled it. I would rotate the pork like this till all was cooked. The last couple runs were kept hot and I reheated the chilled pork as needed in a sauté pan with a bit of finishing/foil juices.

Hope this helps....