chassis
Big,
Yella had some excellent methods, I'll add what I've done many times. In addition to drag racing, I build and fly experimental aircraft for a hobby. Go to aircraftspruce.com and then type in the search window, Adel clamp. These come in sizes by 1/16" all the way up to at least 3" in diameter. For example, MS21919-DG5 is for a 5/16" diameter tube, MS21919-DG18 is for a 1 and 1/8th diameter tube, and so on. I'm not pushing Aircraft Spruce, but just giving you a place that you can go to. There are other suppliers of aircraft grade hardware.
On your fuel line, you would use a larger diameter clamp on the chassis tubing, then put a smaller diameter clamp onto you fuel line, and secure them to each other with a short bolt. When properly sized, they fit securely on whatever they are attached to. They are much more secure, and look much better than wire ties. And no welding required, and you can move them later if you want to. They also come in heat resistant types. And like most aircraft grade hardware and fastners, they are very strong, but also as light as possible. Aircraft and race cars, have one common enemy, weight! Hope this helps you. dgh