Which fuel pump to use ?

Technical advice Q&A

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dal2.0litrefrogeye
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#1 Which fuel pump to use ?

Post by dal2.0litrefrogeye » Thu Aug 06, 2015 10:09 pm

Hi , thinking ahead a little here , but what fuel pump are people runnng ,with tripple webers , and around 300 hp mark ? cheers for any ideas
Its a way of life not a hobby
Darren . 64 4.2 modded 69 4.2

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JEP41
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#2

Post by JEP41 » Fri Aug 07, 2015 5:38 am

Hi,

I have 330 hp at the flywheel and use a facet red top. I have two red top pumps wired in but with a selector switch. One pump is sufficient, I just like the reliability factor of having a backup pump available. Its the gas turbine engineer in me 8)
Kind Regards John

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dal2.0litrefrogeye
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#3

Post by dal2.0litrefrogeye » Fri Aug 07, 2015 6:28 am

Hi thanks for reply , are the pumps plumbed in, in parallel ?
Its a way of life not a hobby
Darren . 64 4.2 modded 69 4.2

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markc555
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#4

Post by markc555 » Fri Aug 07, 2015 9:28 am

Webers hate high fuel pressure, it'll cause havoc with the float chambers (and leaks), so ensure you fit a fuel pressure regulator.

They only need 2.5-3psi of constant fuel pressure but the pump needs to be capable of providing sufficient fuel volume to keep the float chambers full while the engine devours the fuel exiting the carbs.

Cheers

Mark
1969 S2 FHC (Opalescent Maroon) 1R26120

"The older I get, the faster I was"

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Heuer
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#5

Post by Heuer » Fri Aug 07, 2015 10:20 am

The SU AUF 300 range of high pressure pumps are designed to provide approximately 140 pints of fuel per hour at a point about 3 foot above the level of the tank. It is thus capable of supplying fuel at this rate when ascending the most severe gradients likely to be encountered. The fuel pressure is about 3.8psi. On the other hand the SU carburetors are designed for a fuel pressure of 2psi and pressures in excess can result in leaks, increased fuel consumption and overly rich running at idle. Now I know much of the fuel going into a Weber is used to fill the cabin with fumes and give the driver a headache :lol: but even they can't consume more than 17.5 gallons/hour or 3.5 mpg at a steady 60mph

Suggest you fit a Filter King: viewtopic.php?t=164 CMC recommend fitting them on every car they have in for service.
Last edited by Heuer on Sat Aug 08, 2015 10:38 am, edited 2 times in total.
David Jones
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David Oslo
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#6

Post by David Oslo » Fri Aug 07, 2015 6:29 pm

JEP41 wrote:Hi,

I just like the reliability factor of having a backup pump available. Its the gas turbine engineer in me 8)
Do you run seperate fuel lines from the twin pumps, one down each side of the car? :D And what about the reliability of the switch ? The more parts you add the more parts you have to fail :D Interesting SIL calculations to be done!
David
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JEP41
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#7

Post by JEP41 » Sat Aug 08, 2015 5:42 am

Hi,

I have both Facets mounted in the boot and tubed into a 3/8" supply line to the webers via two non return valves in the pump discharge lines to prevent back feed. In the engine bay I use a pressure regulator set at 2.5 psig from memory.
Kind Regards John

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#8

Post by dal2.0litrefrogeye » Sat Aug 08, 2015 10:18 am

Hi much food for thouht , as I said , a little way off yet , but if you dont ask you never know :idea:
Its a way of life not a hobby
Darren . 64 4.2 modded 69 4.2

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D COUPE
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#9

Post by D COUPE » Sat Aug 08, 2015 4:33 pm

JEP41 wrote:Hi,

I have both Facets mounted in the boot and tubed into a 3/8" supply line to the webers via two non return valves in the pump discharge lines to prevent back feed. In the engine bay I use a pressure regulator set at 2.5 psig from memory.

Top planning....just when I thought I had thought of every eventuality

Dave C
ITS NOT WHAT YOU DRIVE ITS HOW GOOD YOU LOOK IN IT

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