68/70Vette

The stock fuel lines are 3/8". I have a new fuel line, Stainless Steel, on the 70. I plan to try to get 600 hp out of the engine (502 Keith Black). If I mount an electric fuel pump in the back of the car, will I get enough fuel? Actually where the fuel lines follows the contours of the rear wheel dog leg and makes bends, the line appears to be a little crimped. So for the crimps I may be getting some flow resistance..how much I don't know.

Also, in addition to the 3/8" line feeding the engine, there's a 1/4 inch return line from the gasoline bypass (the regulator at the carb) to the tank. Is a 1/4 inch enough? I will be putting a fuel regulator on the engine near the carbs, so I'd guess this is OK??? Of course by the time I get this thing on the road, I may want to go to fuel injection......

This is a sensitive issue, since the body is off the frame. I can muck around with the fuel lines now..pretty much as I please. Increasing fuel line diameters, adding bigger fuel return lines,..it's pretty easy now.
Once the body goes back on the frame, I'm pretty much screwed if I want to change fuel line dimensions, etc.

Thanks

ignatz

I have an electric pump at the back with 3/8" lines and a 500 HP motor and things are pretty much OK. However I wish I could go back to the time that the body was off and at least put a return line on that matches the feed line in size. Reason I got from a couple of tech lines is that the back pressure from the smaller return line changes the regulator behavior. The regulators want zero back pressure, hence need a return line that at least matches the feed line. Go read some of the pdf's for the regulators. I have some actual experience with this in that the Mallory fuel log I installed with a built in regulator never worked properly with the 1/4" return. Of course the return line on top of the tank would have to change to match.

Here's a pretty good write up on pump size.

http://aeromotiveinc.com/2010/01/fue...nd-horsepower/

If you determine you want a pump with 1/2" inlet and outlet you have a lot to change including the tank fittings. Perhaps an in-tank pump. I think if I drag raced I might want bigger than 3/8". Haven't had any problems with, say, autocrossing it with full throttle spurts here and there.

7T1vette

The return line should be the same size. When the engine is idling, you aren't using much fuel and the remainder needs to get sent back to the tank. Having a smaller return line will make the pump work harder.

terrys6t8roadster

remembering back to my teen years, GM cars did not have fuel return lines. why does the corvette have one? I'm not using mine [was all afu'd] and don't seem to have many engine performance issues. enliten me please. Terry

AboveTheLogic

Return lines help prevent vapor lock, which isn't as much of an issue after converting to a rear mounted electric pump