Originally posted by GlennCauley
I think there is confusion here.
The question was about the length of the pressure line (pipe to tank), not the fuel line (tank to carb).
A longer fuel line (tank to carb) will help a flipped-over car run longer, since there will be more fuel in the line. However, there may be limitations to the length of fuel line you can use (especially at big races) because you are in essence increasing the fueltank capacity above the 75cc limit.
A longer pressure line will help to "soften" the pressure pulses going from the pipe into the tank. This will help to maintain a more even pressure of the fuel system, which makes for smoother operation (especially at idle). Note that this will result in a less-pressurized fuel system, since you are increasing the volume of the "pressure chamber" which results in decreased pressure. It is a trade-off. I have always used a pressure line at least 8~10" long.
Try this... put a really short pressure line between pipe and tank. Run the car, then come in and with the car off the ground blip the throttle... watch the effect on the fuel in the tank. It may "ripple" the fuel because of the high pressure.
Then install a long pressure line and repeat the process. The effect on the fuel will be dramatically less... no "ripples" in the fuel.
Thanks for the tip
