My 72 has no fuel return line. I'm swapping the 350 for a 455 this spring. My car does not have a fuel return line now. I'm obviously putting in a new fuel pump and have a new tank and sending unit the is set up for the return line. On to the question...Is the return line beneficial enough to make it worth the effort to put a line in? I'd fab it myself with the copper nickel lines, they're way more forgiving than steel.

 

Yes, 100% beneficial. It keeps the fuel cooler through constant circulation which makes more horsepower and helps prevent vapor lock in high temperatures.

 

The return line is not mandatory with the engine swap but as Fleming noted, it's definitely a good idea. The cat urine that passes for gasoline today could definitely use it.

 

That answers that. I knew of the vapor lock thing, but didn't consider the cooler fuel HP benefit. Thank you.

 

Lol cat urine. My daughter has a couple cats... hmm the money saving possibilities. Now I can order the proper pump... one set up for the return. Thank you.

 

Yup, dyno proven on Engine Masters....
Remember the old school cool cans? They worked!

 

Not to mention the hot restart issues.