V8 carb fuel pump

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repton
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V8 carb fuel pump

Postby repton » Sat Jun 20, 2009 11:45 am

I'm after an in line fuel pump to suit my 3.5V8 on SU carbs. Is something like this one on eBay going to be any good. If not, what is?

I could also do with some kind of valve for the breather on the tank. I know when Dave did his on the 100" he had two, one pointing each way so as to allow excess pressure out and of course air in when the engine is running. If something like this on eBay suitable? Presumably I could get something cheaper than that though as I'm not bothered about it being shiny!

Thanks,
Paul

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davew
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Postby davew » Sat Jun 20, 2009 1:31 pm

The Pacet fuel pumps will do the job although they're not cheap. Avoid the 'solid state" ones as shown on that ebay link as IME they don't last very long and need to be much closer to the tank than the normal style.

If you're in or around Harrogate in teh near future, Northern Mini Spares have them in stock.

On the breather valves, I've changed over to a single valve now from Mocal (Think Automotive) that is normally closed and opens to let air in or out as required. Seems to work pretty well and only requires a single vent.

The valve will open to admit air into the tank when a negative pressure of 0.0055 bar (about 0.08psi) has been sensed. Should the tank experience over pressure, the valve will open to exhaust excess positive pressure once a figure of 0.05 bar (0.725psi) is reached.


The Mocal part number is TPV8 but it's not cheap at around 30 quid... I used to use the Land Rover valves but had some issues when one of them failed and stuck open all the time.

repton
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Postby repton » Sat Jun 20, 2009 6:36 pm

Thanks for that Dave. Is this the sort of fuel pump you mean?

Ta,
Paul

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davew
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Postby davew » Sat Jun 20, 2009 10:50 pm

Yep, that's the type to go for. They do a range of "tops" depending on fuel flow. I have a feeling that I used to use red tops but it's been a looooong time since I had a carb V8 !

It's worth bearing in mind though that the in-tank pumps tend to last longer and cost about the same if you're sticking with the standard fuel tank. I assume this means you got a new tank at last ?

bandiflip
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Postby bandiflip » Sat Jun 20, 2009 11:37 pm

youre right Dave..Red top is OK for V8..I had one on my drag car.....
do you know the meaning of Nemesis ???

repton
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Postby repton » Sun Jun 21, 2009 7:47 am

davew wrote:Yep, that's the type to go for. They do a range of "tops" depending on fuel flow. I have a feeling that I used to use red tops but it's been a looooong time since I had a carb V8 !


They reckon the silvers are good for up to 200bhp and the reds for 200+ and my 3.5 isn't going to have anywhere near 200, but it might make sense to go for the red top anyway as it's only 4 quid dearer.

davew wrote:It's worth bearing in mind though that the in-tank pumps tend to last longer and cost about the same if you're sticking with the standard fuel tank. I assume this means you got a new tank at last ?


I have (only taken 18 months!) but it's not a standard tank, I've had a shiny new one made up to go in one of the side lockers out of the way.

Paul

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Matthews
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Postby Matthews » Sun Jun 28, 2009 6:30 pm

Best bet for reliability is a 90 in tank pump (or 110 one as long as it's not efi) I've also had reliability issues with the facets, the other problem with silver and red tops is the pressure (you needs lots of flow at 3.5psi) if you don't fit a limiter or return with a restrictor in it you'll just flood the cards all the time as the float valves get blown open (hence why mine have viton valves to help with the problem) . You also get a big pressure drop problem when using the 110 tank in standard situ when going vertical and it's a long way uphill from the tank to the carbs in a 110 but this shouldn't cause you the same issues if the tanks in your locker.
Matthew


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