Let me give you a warning about those long thin throttle return springs.... Although dual return springs are recommended (required in most racing venues), there is a right way and a wrong way to implement that setup. I found out how to do it the wrong way. One of my cars had long, thin springs that were strung next to each other. One time they vibrated together when I was on the throttle and jammed their coils together so the throttle would not close. Arrrggghhhh..... full throttle down the street toward a traffic light. I quickly pulled out the choke enough to kill the power by going full rich mixture just in time to get it stopped. An inspection revealed the tangled springs. A new setup worked far better and was more reliable.