Torque on SMA connectors is very important and touchy. The torque applied to SMA connectors seems to vary between 5 in-lbs and 9 in-lbs depending on where you look. Pasternack sells a really pricey ($300+) torque wrench specifically for SMA connectors that is set for 8 in-lbs.
I was peripherally involved in a failure analysis & review board that investigated installation problems in which an assembler tech used the special torque wrench set to around 9 in-lbs (or maybe 11 in-lbs memory fails me at this point) then gave it another 1/2 turn because he didn't think that the torque wrench got the connector tight enough! These were CRES SMAs that were on stuff that went to 18GHz and were obviously quite special in every way.
2sheds