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Fuel pressure with Strombergs


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I have been running twin 175 Strombergs on my 6 for around 22 years, these are fed by a Facet pump in the boot.

 

The pump had become problematic earlier this year so I replaced it with a new Facet pump. I now have bypass issues at the carb needle valve. I understand the facet generates up to 5psi and this may be a little high for Stromberg carbs, does anyone have a fuel line pressure regulator fitted for this set up ?

 

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The Stag has a little pump in the boot which gives a gentle thumping noise when you first switch the ignition on (prior to starting) which reduces in frequency as the pressure builds up. Presumably a Stag pump could be used on a TR as I think the pressure requirements are similar for the twin Strombergs of the Stag.

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I would avoid a pressure regulator on a carburetted engine, it is adding complexity and probably a continuous overflow back to the tank.

I would buy a proper pump instead.

Waldi

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1 hour ago, Waldi said:

 

I would avoid a pressure regulator on a carburetted engine, it is adding complexity and probably a continuous overflow back to the tank.

I would buy a proper pump instead.

 

Is really no problem. Before my EFI I had 2 ZS Strombergs with FilterKing regulator and Pierburg electrical pump. Works perfect. 

Jochem

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Hi 

I  have CD175s on my 6 supplied by a Facet pump (I think the pump is intended for a boat) mounted under the bonnet, I had a Sytec regulator fitted which gave problems from day one so changed to a Malpassi regulator, this has been absolutely trouble free for the last five years.

Prior to fitting the Facet pump I had the standard mechanical pump which occasionally caused some overflowing issues. My TR3 has SUs and the standard pump and this also occasionally overflows, I have replaced the float chamber needle valves but still it will flood now and then especially if the car has not been used for about a week

George

 

 

 

 

 

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11 hours ago, pheaney said:

Hi I use a facet silver top pump (480530K) for my Strombergs .

It comes rated at 5-6 psi but I replaced the internal spring 

with a 3 psi replacement to be sure.

 

https://www.ebay.co.uk/itm/230984130252

 

Regards Paul.

 

 

 

 

thanks Paul, that is really helpful, I had no idea springs were available

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3psi will still give a head (height of fuel column above the pump) of around 2.5 m.

That should be more than enough. If a lower rated spring like 3 psi or less is available I would try that first. There is often some margin in the design, so 3 psi might stop the flooding.

Waldi

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Just a thought about fuel pumps. In the 50+years that I have been puttering with TRs, the stock mechanical pump has never been a source of trouble, unlike electric ones. The original AC brand pumps can be rebuilt with kits available and are bullet proof. Stay away from the low cost non-rebuildable pumps.

Berry

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The only problem with the mechanical pump is that if the car is not used regularly it can take a lot of cranking to fill the carbs again. The electric pumps are inexpensive and small so once you have done the conversion it is easy and quick to swap the pump with a spare that you always have with you.

I dont see a problem with using a regulator but there are suitable pumps off the shelf that operate at the correct 1.5 to 2 psi.

Stan

 

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Why not use a Huco pump designed for the job giving 2.1psi.  https://www.dellorto.co.uk/shop/car-accessories/fuel-pumps-regulators-accessories/huco-low-pressure-12v-fuel-pump-133010/

I have used one in my TR4A on SUs for a number of years with no problem.

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57 minutes ago, foster461 said:

The only problem with the mechanical pump is that if the car is not used regularly it can take a lot of cranking to fill the carbs again.

Which maybe could be argued as a good thing because it allows oil pressure to build up before the engine fires. (Unless you crank it first with the plugs out of course).

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I'm a fan of electrical pumps! Instant start up and vapour lock is a thing of the past, it also came in handy when a friend ran out of fuel, we disconnected the fuel line from my carb and pumped fuel into a bottle to tip into the empty cars tank.

One of our group had a scare with his mechanical pump, he had left the back of the car on ramps while he was away from home for a few days, when he got home the house stank of petrol. He went into the integral garage and found that the fuel tank had drained through a faulty pump into the sump then when that was full it found its way out onto the garage flour. Luckily it was Summer and the boiler had not fired up and caused a big bang.

George

Edited by harlequin
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Not to over beat the drum for mechanical pumps, but it is also possible for the fuel to make its way into the crankcase through a float valve that is stuck open.  With either type of pump, it is cheap insurance to install a shut off valve and close it before long term storage.

Berry

4 hours ago, harlequin said:

One of our group had a scare with his mechanical pump, he had left the back of the car on ramps while he was away from home for a few days, when he got home the house stank of petrol. He went into the integral garage and found that the fuel tank had drained through a faulty pump into the sump then when that was full it found its way out onto the garage flour. Luckily it was Summer and the boiler had not fired up and caused a big bang.

 

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