Yes, you are asking for trouble. Torque specs are not pulled out of the air. You want to stretch those bolts just right -- not too little and not too much.
A basic, torque wrench (you know, with dual rods and a dial-indicator with an "arrow" pointer) costs maybe $15. As long as the arrow points to zero before any load is placed on it, the tool is properly calibrated. If nothing else, pony up the money for a basic torque wrench. You'll be in much better shape than trying to guesstimate (which you can't reliably do, anyway).
And besides, anyone who works on their own car should have one.
