Flame on gas hob not correct.

I'm not sure what you mean by a proper efficient flame. I just recently went through an experience I'll relate to you here. I purchased a GE Profile dual fuel range. I can get more specific if you'd like but here's the point. The highest burner on the range was rated at 17000 BTU's. A friend recommended the range to me and sang it's praises. I took delivery of my new toy and couldn't wait to get a pot on the stove to start cooking a long wait for pasta. Twenty minutes later I was finally seeing bubbles! I spilled the water out and measured 12 cups of water into the pasta pot at room temperature. That's three quarts of water. 20 minutes to see bubbles and never would it come to the expected "rolling boil". My experience has always been with electric ranges and I am new to gas but 20 minutes? Something had to be wrong, right? Wrong! Much research later I've found it is common for natural gas to LP conversion stoves to lose a good deal of their oumph when converted. GE as it turns out is one of the most notorious for a serious degredation in BTU output. After exploring GE's site I found that this same stove running under LP gas is rated(for the highest burner) at 11000 BTU's! No wonder I couldn't boil water! Back to the store it went and I am still in search of a stove that will meet my needs. Don't know if this will help you or if this is the same issue you are dealing with but maybe just maybe. Good luck!