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Old 04-14-2008, 08:58 PM
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Electric/Mechanical Fuel Pump Question

I'm trying to decide if my build will need an electric fuel pump over the mechanical. I'm building an SBC 383 that will be a street machine (RPM range of 2000-7000), being fed by a 750CFM Mighty Demon. Is it necessary to go with an electric fuel pump? If so, what all needs to be modified/what would I need in order to install it?

I don't really know the benefits of electric other than it's...electric, and maybe that it can provide constant fuel pressure at the same rate at all RPM's? Is it really that necessary? or would a mechanical pump serve the purpose just fine?

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Old 04-14-2008, 09:18 PM
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Electric Or Mechanical

In your application there is no reason you couldn't use a mechanical pump.They flow more volume of fuel that will increase with engine rpm.I currently run a Keith Dorton mechanical pump on a 357ci 8-71 blown twin 750cfm holley's and have no problems.The pump flows 170gph.
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Old 04-14-2008, 09:30 PM
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Quote:
Originally Posted by BORTI
In your application there is no reason you couldn't use a mechanical pump.They flow more volume of fuel that will increase with engine rpm.I currently run a Keith Dorton mechanical pump on a 357ci 8-71 blown twin 750cfm holley's and have no problems.The pump flows 170gph.
right on, think i'll take that advice. what are the advantages of an electric one though? is it like having an electric water pump, but for fuel?
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Old 04-14-2008, 09:44 PM
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The only electric fuel pump I have ever installed is on my own vehicle as a theft device, and it causes it to run out of fuel when hot and trying to pull a steep grade. I am going back to a mechanical pump when I get it out of moth balls. Every hotrod and all race engines I have built, been a crew chief of, or work on now in my shop, have mechanical fuel pumps. Just get a good one and enjoy.
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Old 04-14-2008, 09:46 PM
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fuel pump

The only advantage I can think of is constant fuel pressure/volume.And maybe with a race car making hard launches the fuel is pushed rather than pulled.It also can make more psi for running injection.But on the street I see no real advantage,I guess I'm just old school.
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Old 04-14-2008, 10:19 PM
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Quote:
Originally Posted by BORTI
The only advantage I can think of is constant fuel pressure/volume.And maybe with a race car making hard launches the fuel is pushed rather than pulled.It also can make more psi for running injection.But on the street I see no real advantage,I guess I'm just old school.
cool, thanks guys. I see you're running a 170 GPH pump, feeding two 750CFM carbs. I don't think I'll need quite that flow rate. What would you suggest? 100-130GPH range?
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Old 04-14-2008, 10:47 PM
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fuel pump

Edelbrock makes some real good mechanical pumps,130gph would be fine,even less would work.But having more won't hurt,just make sure you use a regulator.
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Old 04-15-2008, 08:59 AM
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I wanted to try the electric fuel pump setup on my 496 BBC with an 850 CFM Speed Demon, so I installed a holley "blue" pump which I think is 110 GPH. It has never given any problems, but it sure was a pain in the *** to hook it all up. But if it is done right it really is a neat setup. I mounted the pump, filter, and relay to a diamond plate panel, then ran a supply line and bypass regulator (which any good electric fuel system should have). So all in all I had probably 36 feet of fuel line.

It is extremely noisy though, but I like to turn the key to the "on" position and listen to it wind up before I light the fires on that BBC. It is alot of fun to watch people take a step back when they hear that big motor about to light up.
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Old 04-15-2008, 09:12 AM
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I would run a mechanical if you can. they are more durable, much quieter, and don't need any wiring.

if you want to or need to run electric, then get a mallory pump (comp110 or comp140). they are quiet and fairly durable if you use a filter before the pump and mount them low and near the tank.
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Old 04-15-2008, 10:52 AM
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Whichever you choose, install a temporary fuel pressure gauge on the cowl so you can monitor pressure during driving. Take the reading off at the fuel line entry at the carb. Any current carb will run fine at 5 - 5 1/2 lbs. Any more than that and you risk overpowering the needle and seat and flooding the motor with fuel. If pressure at the carb is excessive, adjust your return regulator.
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Old 04-15-2008, 10:55 AM
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Quote:
Originally Posted by techinspector1
Whichever you choose, install a temporary fuel pressure gauge on the cowl so you can monitor pressure during driving. Take the reading off at the fuel line entry at the carb. Any current carb will run fine at 5 - 5 1/2 lbs. Any more than that and you risk overpowering the needle and seat and flooding the motor with fuel. If pressure at the carb is excessive, adjust your return regulator.
yea, i'm going to install one inline between the carb and pump, and hopefully mount it near/close to the inlets on the carb itself.
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Old 04-15-2008, 11:26 AM
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GM never saw the need for electric pumps on the L-88 427, LS-5 and LS-6 454, ZL-1 427, or DZ-302 engines just to name a few. Electrics are just plain un-necessary on the street.
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Old 04-15-2008, 11:52 AM
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Quote:
Originally Posted by cool rockin daddy
GM never saw the need for electric pumps on the L-88 427, LS-5 and LS-6 454, ZL-1 427, or DZ-302 engines just to name a few. Electrics are just plain un-necessary on the street.

....unless you have fuel injection....
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Old 04-15-2008, 12:43 PM
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you will also need an electric on tight engine swaps if there is no room for a mechanical pump and many later model engines don't have the mechanical pump provision.
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Old 04-15-2008, 02:14 PM
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Right!!! Like Gen V big block chevy's. They don't have anywhere to bolt one on.
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