Mechanical or electrical fuel pump

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440DART1970

440DART1970

1970 Dart 446ci Swinger
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Getting to that time where I need to decide whether I'm going to run a mechanical fuel pump off the engine or put in an electric fuel pump... the motor will probably be pushing a little over 500 horsepower on the street with a Quick Jet SS-760 carburetor

what's the pros and cons?
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If you run mechanical, make sure you have proper arm clearance if using a double roller.
 
1978 RV 440 motor. +30 0ver = 446ci 10.35.to1 fordged TRW Speed Pro pistons, Steel crank internally balanced. Comp cams .488 ,491 lift - Duration @.006 274, 286. 915 heads slightly cleaned up ports, upgraded vale train & Springs, Johnson BB lifters, Aluminum water pump housing and water pump, Speed Pro Harmonic balancer, Holley Street Dominator intake, Holley 750 mechanical DP, MSD 6AL, MSD 8546 race distributer and coil, Schumacker Ceramic coated Tri-Y header, Motor mounts and Torque arm.

1970 Dodge Dart Swinger California car brought to east coast 15 months ago, rust free. .920 torsion bars, Kelsey Hayes 4 Piston caliper disk brake set up, Mancini rear HD race leaf springs and shackels, 8 3/4 a body rear with sure grip center with 3.55 gears with 11in Chrysler New Yorker rear drums. 727 trans 2400 stall speed manual vale body (undecided) and God only knows what else I forgot..
 
More so importantly, what size of a fuel line from the tank are you using? The stock size that fed the /6 or 318 or whatever, ain't gona cut it with the new BBM.
 
I like electric with a good return system. Look at modern cars.
 
Nice pile of metal you got there lol.....

Seal the deal for yourself. Electric Intank with a return. You have spent the money on the motor so a little more won't kill ya....

Once I get a few miles on my 72 the Mechanical Pump is history and I will do an Intank and ,y powerplant will make way less power than you. I just think it eliminates a whole bunch of variables in older cars....

Good luck,
JW
 
I'd go electric. For 500 hp, it's a lot easier to push fuel under pressure from the tank than to suck it all the way to the front of the engine... no vapor lock on hot days with pump swill either. No cranking to fill the carb bowls if it's evaporated or you worked on it.
 
I ran a 440-6 with .550 solid roller in my 70 Charger using mechanical and stock 3/8 line.

Low 12s @ 116 mph....shifting @ 6800 in a 4000lb car with driver.

No issues
 
A long time ago I was taught that an internal combustion engine needs; 1/2 pound of fuel, per horsepower, per hour.
So then; 500hp needs; 500 x 1/2 =250 pounds per hour of fuel
250pounds/6.25pounds/g =40gallons per hour
40g x 128oz per g /60minutes=85 ozs per minute, for 500 hp.

the 1969 FSM lists the factory pump as
"The fuel pump should supply 1 quart(128/4=32 ounces)of fuel in 1 minute or less at 500 rpm"
The manual does not say that this spec pertains to any particular pump on any particular engine. Ergo, one could make the leap that this spec pertains to all factory pumps for all engines,in 1969.
And if that is so, then even a slanty pump can feed 188 hp at 500 rpm.
I'm not gonna make the leap that the same pump that puts out 32 ounces at 500rpm will put out 10 times as much fuel, at 10 times the rpm (that would be 320 ounces at 5000 rpm). No, I'm not suggesting that at all.
What I'm suggesting is that the mechanical pump can put out a lot of fuel, can put out adequate pressure, and both the pressure and the volume vary with rpm, perfect for an internal combustion engine.

The P4007040 small-block pump has no trouble keeping up with my 400hp plus SBM.It is rated to [email protected]
There is a BB version,P4007039, that is rated the same.
80gph is; 80x128/60=170 ounces per minute, or 100% higher rating than what the formula says you need.
Mopar says it feeds hemis.
You decide.

Ps; I converted the 80gph to liters per hour, if you need to know that; and my math says using 1qtUS = .914 liter;
80gallons x 4qts per gallon x .914conversion=292 liters/hour
 
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yeah... what he said.. ?? lol

Does the extra float bowl capacity of the 3 carbs on a 6pak change anything as far as 1/4 mile goes ?

hmmm...
 
I'm refering to the extra capacity of fuel in the bowls... I got thinking about it one day at the track when some yahoo said I needed 1/2 inch fuel line to support my 340 with a 830 DP... I responded that if 3/8 line could support my 440-6 it surely can support a 340 . Which got me wondering..
 
Well, you could put ten bowls on there and once they are full,the pump wouldn't know the difference. The pump only needs to supply for the horsepower. So don't be supercharging it!That would be a new equation.
And since that Mopar pump can deliver 170 ounces per minute, Ima thinking it can fill 3 empty bowls likity-split. Ima thinking those bowls are about 55cc or so. That would be about 2 ounces,if my math is good. So 2 oz x 3/170 times 60 seconds = 2.118 seconds to fill, at who knows what rpm, with that Mopar pump.
But the factory rated pump, at 32 oz per minute at 500rpm, puts out 32/500=.064 oz per revolution,(actually 2 x .064=.128 oz per every 2 revolutions, when the eccentric comes around and strokes it). So at a cranking speed more like 400 for a V8, it would put out 400 x .064=25.6 ounces in one minute.And filling empty bowls would look like; 2x3/25.6=.234 minute or .234 x 60=14 seconds; at 400rpm. I guess likity-split this one ain't....lol

What the spec sheet doesn't tell you is at what rpm the 80 gph was measured at, nor at what pressure it was running when it was delivering that 80gph.
I don't care for the way these pumps are rated but it's what we got.
But the best clue in Mopar's hype is that they say it can feed BigBlocks and Hemis. And it's been said, that,even the lowly street-Hemis were probably belting out over 500hp back in the day.
 
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I'm thinking more about the extra reserve for running 1/4.

Wow... Great goal by the Jets !
Of course you are watching the game right.?
 
It is a pain in the rear to be priming the carb all the time if your vehicle sits for a couple of days. I have three Mopars (with carbs) and some day I am going to go electric on all of 'em so they start when I turn the key. I would suggest everyone else do the same.
 
440DART1971 said:
1978 RV 440 motor. +30 0ver = 446ci 10.35.to1 fordged TRW Speed Pro pistons, Steel crank internally balanced. Comp cams .488 ,491 lift - Duration @.006 274, 286. 915 heads slightly cleaned up ports, upgraded vale train & Springs, Johnson BB lifters, Aluminum water pump housing and water pump, Speed Pro Harmonic balancer, Holley Street Dominator intake, Holley 750 mechanical DP, MSD 6AL, MSD 8546 race distributer and coil, Schumacker Ceramic coated Tri-Y header, Motor mounts and Torque arm.

1970 Dodge Dart Swinger California car brought to east coast 15 months ago, rust free. .920 torsion bars, Kelsey Hayes 4 Piston caliper disk brake set up, Mancini rear HD race leaf springs and shackels, 8 3/4 a body rear with sure grip center with 3.55 gears with 11in Chrysler New Yorker rear drums. 727 trans 2400 stall speed manual vale body (undecided) and God only knows what else I forgot..
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Can I ask where you got the water pump and housing? Decent quality? Costly?
 
mbaird said:
I ran a 440-6 with .550 solid roller in my 70 Charger using mechanical and stock 3/8 line.

Low 12s @ 116 mph....shifting @ 6800 in a 4000lb car with driver.

No issues
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Good info, thanks!
 
Last time I went through my engine I installed a mechanical fuel pump. It runs great but it started much better with the electric.

My car regularly sits for weeks or months at a time without being started.
 
I always use mechanical pumps unless I have no choice. I prefer the simplicity and most of all the silence of a mechanical pump. I have a 440 in my Gold Duster. Not sure about how much power it has but it weighs 3500# with me in it and has run a best of 7.06 @ 96 in the 1/8 mile and 11.125 @ 121 in the 1/4 mile. The 60 ft times are in the 1.50s with a best of 1.545 and I currently have 5.29 gears in the axle and also an A-518 overdrive trans. I've also ran 4.57 gears so I estimate its making around 550 at the crank. I have a Clay Smith Engineering pump, 16 psi and 160 gph. The rest of the fuel system is a Holly 850 DP, a JAZ 16 gallon fuel cell with 3/8 aluminum fuel line to the pump and I use a simple Enderle check valve as a bypass regulator. The bypass goes to another 3/8 aluminum line back to the fuel cell. No wiring, no switches and best of all no noise. I've been running it since June 2014 with no issues at all. I have not been to the Clay Smith web sight in a few years so I'm not sure if they're still selling the pump. If Clay Smith no longer sells the pump you may be out of luck because when I searched for the right pump it was the only one I found with enough fuel volume. If you do go electric and its a street car I recommend spending the money on a good high quality pump that is not too noisy. Magna Fuel, Aeromotive and probly some other companies have them. I've had a couple of Holley blue pumps and they are very loud, like an alarm clock buzzer.
 
AJ/FormS said:
On the street? Only on the street? with street gears?
Mechanical.
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This... No electric B.S., done both mechanical & electric... I would run at least a number 6 AN , 3/8 "ths fuel line.( don't forget the bigger pickup line,if ising a stock style tank...).
 
dibbons said:
It is a pain in the rear to be priming the carb all the time if your vehicle sits for a couple of days. I have three Mopars (with carbs) and some day I am going to go electric on all of 'em so they start when I turn the key. I would suggest everyone else do the same.
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Sounds like you have some other problem. Mechanical pump with a Holley on mine and I rarely ever have to crank it for more than three seconds even if I have not started it in a month.
 
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