[HSSS427]

.... was the excerpt below from Don Gould's Demon Carburetor Tuning guide:

There lot's of thing's that determine fuel requirements, there’s some redundancy here but let’s review and let's analyze the whole system:
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1. You have a 1/2 line, that's very good, but what size are the inlets and outlets on your pump? The answer of course is 3/8" so your pump will only flow at the rate allowed by the smallest orifice in the system, remember electric pumps are gravity fed so although the outlet side will flow more volume due to the pressure the inlet which is gravity fed is the limiting factor. >>
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2. Let's use a 12 second flat car for an example. I would think we could all agree that this car would burn about 1/2 gallon of fuel to make a 1/4 mile pass. So if we do the simple math to determine GPH (Gallons Per Hour) 1/2 gallon x 5 (60 secs. / 12 sec pass = 5)= 2.5 gallons per minute x 60 minutes = 150 Gallons per hour, far beyond the capacity of a Holley Blue or most mechanical pumps.>>
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3. So we've determined how much fuel we need to make a pass and the capacity of the pump required. But what about the gear ratio in 1st of about 2.50:1? Does this have any affect? Of course, we all know from experience that a car will use way more fuel at 30 MPH in 1st than it will in at 30 MPH high gear so we need to make allowances for the huge consumption rate in 1st and 2nd gear. Some of this is built into a Demon with the larger float bowls creating a built in reserve, but if the pump can't keep up the floats will drop and the carb will not be able to maintain a flat fuel curve as demand increases. Do you think that maybe 20% more fuel would be a fair number to use? So we're now up to 150 + 20%= 180 GPH.>>
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4. Let's not forget G forces, does your fuel line run from the cell straight up the carb taking the shortest route possible? By running the fuel line in this manner you further complicate the G forces working against the pump, all the fuel in the line is pushing back against that pump and in extreme cases can actually stall the pump (Remember the main feed line from the tank to the pump (Gravity fed) it's going in the opposite direction also starving the pump of adequate supply)>>
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The correct way to plumb a car for optimum fuel delivery would be to have the main line come all the way to the front of the car, we run them through the radiator core support, a big 180* loop and back to the regulator. Now when the car launches G forces drive the fuel to the regulator giving it a supply while the pump recovers from the G forces of the launch. So if your running your lines in what is probably not the best location then I think a 10% increase in pump capacity should now be factored into the equation....180 + 10%= 200 GPH>>
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So how's your fuel system holding up so far?>>

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5. I'll bet you have your regulator mounted to the engine or chassis right? Another No-No....as the engine starts to wind up and the car builds speed that regulator is getting the ever loving ***** rattled out of it. In allot of cases so violently that the spring can't hold the ball on the seat so it releases fuel and can overflow the float bowls. You've all seen this at the track...a car gets about 300' out and it starts leaving a black haze behind it.>>
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6. Feeding the carb from the regulator is another consideration, if you running a dual feed line that uses a T and splits off to feed the bowls your probably OK to about 350-400 HP with a Mechanical Pump. After that, we recommend you consider an Electric Pump and 2 port regulator and supply each bowl with a -6 line from the 2 available ports on a good regulator like the BG 2 port or Aerospace 2 port. These lines need to be as short as possible we use a 7.5" line with a 45* on one end and a straight on the other with the either 2 port it works perfect. Too large of lines or too long of lines will cause the regulator to respond slowly as there's more fuel volume to drop in pressure and more volume to fill to get back to full pressure.>>

And, yes it's a hobby, and like any good hobby you have to spend money on shiny new toys that relate don't have that big an impact in the end ie do you really need that new driver with a head the size of a football when you play one round a month and can't break a 100? Absolutely!!