While I think that this question belongs to the tech forum, I have a few answers for You:
Certainly they ALL can glide, even the concorde, as every normal descent is with idle thrust, but I don't know about the glide ratio.
With the MD80 we had a simple formula for all-engine flame-outs: Double the FL / divide by ten is tha max. recommended distance in NM to the airfield. e.g. from FL 310 You shouldn't aim to a field which is further than about 60 NM out. This formula allows for a normal landing with gear down and full flaps on short final, when You can judge the glide more accurately.
As we used to start descent in normal operation out of FL 290 from 90 NM out with idle thrust and 290 KIAS, the glide ratio should be better than 1:19 which isn't bad at all, and way better than any single-engine prop aircraft.
Hope it helps