[Healeys] Why carry spares

[Chris Dimmock]

It's pretty simple to test.
Just disconnect the fuel line, point it into a bucket, turn the one pump on,
run it for 30 seconds, and measure the volume of fuel in the bucket.
Empty the bucket.
Then turn both pumps on, run them for 30 seconds, and measure the fuel pumped
into the bucket.
Report back here.......
That volume of fuel x2 is the delivery volume per minute.....
X 120 = volume per hour.
It's not Formula one, close enough is good enough, you won't get in trouble
with the FIA....
Easy.
Best
Chris.

Sent from my iPhone

> On 20 Mar 2014, at 11:14 am, rwil at sbcglobal.net wrote:
>
> Could it possibly be time for some physical measurements on a test
> setup to see: what output pressure with two pumps in series, both 2 SU
> and 1SU and 1Facet (or similar), and in parallel? and what happens
> when one of the pumps in series packs it in?
>
> From reports here it looks as if SU pumps are pretty patient with all
> possible setups.
>
> -Roland
>> On Wed, 19 Mar 2014 16:01:59 +0000 (UTC), you wrote:
>>
>> OK, I'm not a theoretical physicist, and don't play one on TV, and we're
not
> talking electronics so I don't see how running two pumps in series doubles
the
> output pressure. AFAIK, the output pressure of an SU pump is determined by
the
> strength of the spring that pushes the diaphragm (presuming the solenoid is
> strong enough to compress an even stronger spring). There may be some
internal
> 'regulation'--there is a small hole between the input and output chambers
on
> BN1/2 pumps that may provide a pressure limit by bypass--but no real
pressure
> regulation. So, if the spring is capable of producing, say, 3PSI when the
> solenoid is switched off, then the output to the second pump will, at most,
> push the spring back some but it wouldn't add to the 3PSI.
>>
>> IOW, a spring capable of pushing a diaphragm at 3PSI won't be able to push
at
> 6PSI, just because the incoming pressure is greater. Anyone actually
measured
> the pressure of two SUs in series?
>>
>> Bob
>>
>> ----- Original Message -----
>>
>>
>>
>> Two pumps in series might not be suitable for a racing Healey, but they
have
>> worked just fine on my street BJ8 without any problems for a long time.
>> It's just simpler to plumb them in series than in parallel, in my opinion.
>> If you have two pumps in parallel with separate switches, then you can run
>> both pumps at the same time and get twice the flow rate at the same output
>> pressure. Running two pumps in series at the same time will provide the
>> same flow at double the output pressure - not good for the carbs. So, for
>> pumps in series there should be only one switch to prevent running both
>> pumps at the same time.
>>
>>
>>
>> Steve Byers
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