I like to use one of those phillips head drivers that you hit on the end with a hammer which then turns the screw a little. Sometimes if you try to turn a screw by brute force the head can shear off. By shocking it with this type of impact driver, it will break it loose instead of breaking the head off.

 

great idea i'll try to remember that in the future

 

Good tip! Put a little bit of valve lapping compound on the screw and that also works wonders.

 

+1 Alway keep valve grinding compounding on hand. A dab on the end of a phillips head screwdriver is amazing. A couple of bucks at the auto store.

 

OK I read this post yesterday and thought Yeah right. Today Im out in the garage with my carb on the bench and Im trying to get the float bowl screws out. Im trying real hard and they won't budge. I look up and there on the bench is my cordless drill. So I grab it and set the clutch about half way with a Phillips bit. Low and behold they come right out after a little impact action. Great tip thank you very much.