Tightening the Screws
Most appliances that utilize natural gas, such as stove tops, have burner valves that are open a bit wider than a burner that utilizes propane. To tighten these valves, take a small, flat-bladed screwdriver and tighten the screw inside the top burner valve that regulates how large or small the flame is. Tightening this screw will produce a smaller flame, which is ideal for propane. Next, turn the regulator, which is underneath the vent cap, over to the side that says "LP," meaning that the side that says "NAT" should now be face down. Note that you must also tighten the screws of the bake burner and broil burner as well. The bake burner screw is usually under the oven's range, while the broil burner's is typically inside the oven.
Test it Out
After you've tightened all of the burner valves, you want to attach your propane supply to its corresponding burner valves. Because every oven is different, it's best to follow the installation instructions that come with your stove or oven. Note that most appliances utilize either a color- or number-coded system, which allows one to easily match up the valves on the tank to the valves on the appliance. Once this is completed you want to turn the oven on. It may take a few minutes for the new gas to run through the valves and ignite. If you feel your flame is too big or too small you can adjust this by tightening or loosening that valve's corresponding screw. Remember that a big flame occurs because the propane is getting too much air, meaning that you must tighten the screw more. A small flame means it's not getting enough air, so you must loosen the screw.
If you are uncomfortable working with so many screws, valves and gases, consider purchasing a fuel conversion kit that will allow you to convert to and from natural gas and propane. These kits typically sell for less than $40, and can be found in most major hardware stores. These kits can usually be used for dryers, boilers, water tanks and furnaces. Before you convert any appliance, be sure to check the laws in your state to ensure that it is not illegal to convert certain appliances to propane. You also want to check with your manufacturer to make sure that your appliance allows for a conversion.