I think I read here a long time ago, or maybe in a casting manual, light your propane first and adjust your flame to 16", then slowly add in the oxygen until your flame is 1/4-3/4" , depending on alloy. The gauges on the bottle only work if youre wide open on the torch, I adjust my flame manually on the torch. Youre looking for blue cones about 1/4", its always better to have more gas unless your casting gold.