The manual says to get the top of the tiller level.
If they specify a torque setting in the manual, I will use those numbers and it called for 17.5 ft. lbs. and my bigger torque wrench only goes down to 25 ft. lbs. So I just take the 17.5 ft. lbs. times 12, gives me 210 in. lbs. then I use my inch lb. torque wrench. If they don't give me torque settings I will tighten it with a ratchet so it feels like it's tight, then I'll check it with a torque wrench and that's how I'll tighten it up the next time.