Fuel pump for carb motor

[RoadRacer]

If you have a ~400hp (or less) carb motor what pump are you running? Something as simple as https://www.summitracing.com/parts/sum-g3136-1/overview/ ?

I plan on running the supplied 5/16 fuel & 1/4 return lines, and using a firewall-mounted bypass regulator and pressure gauge. Most seem to say the pump regulator is fine though, so I may skip that (and the return line).

There's more room for the pump at the rear, but I'd love to see where you've mounted yours..

[ram_g]

Why electric at all? For a carb'd motor there's nothing to beat an old school mechanical fuel pump. Highly reliable, proven, no return line to worry about, and safer in the event of a crash as it doesn't pump if the engine is not running.

[RoadRacer]

Very good point. Kinda obvious and like you said.. even simpler. Thanks

[Ray]

I'm running a Holly Blue fuel pump which is low pressure and doesn't require a return line.

Ray

[NAZ]

I suspect you'll find more support for OEM style engine mounted mechanical pumps on this forum. The mechanical pump's advantages are they're cheap and simple and will support most carbureted applications with low to moderate fuel supply needs. However, an engine mounted mechanical pump is at a disadvantage due to the forward location relatively far from the rear mounted tank. A pump, mechanical or electrical, relies on atmospheric pressure and head pressure (the vertical height of the fuel column) to push fuel from the tank to the pump (and you thought they sucked). The pump actually creates a low pressure on the suction side which makes it easier to vaporize the fuel in a hot fuel line. A mechanical pump being mounted on the engine and in close proximity to heat generated by the exhaust can lead to vapor lock. The other disadvantage of an OEM style engine mounted pump is the length of the suction line from the tank. There is more inertia on the suction side which the mechanical pump has to overcome during acceleration. It's easier to overcome this inertia on the pressure side of the pump than the suction side. Rear mounted electrical pumps, especially submersible pumps don't share these disadvantages, however, they are more expensive and complicated than the OEM style engine mounted pumps. There are also safety concerns that have to be mitigated when using an independently powered pump -- these are easy but add cost and complexity. For a moderately powered street car sporting a carb it's hard to argue against the simple engine mounted fuel pump. For my particular application that sees in excess of 2-G's of acceleration a rear mounted electrically driven high-flow pump has the advantage over an engine mounted mechanical pump. Your needs may be very different. So if you go with a mechanical pump make sure route the suction line away from heat sources as best you can. And if going with an electrical pump make sure to mount it as close to the tank as possible and below the tank bottom is better than above it. And consider adding at least an inertia switch to the electric fuel pump to cut power to it if you crash.