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peter scott
Joined: 18 Dec 2007 Posts: 7120 Location: Edinburgh
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Posted: Sun Feb 14, 2021 10:01 pm Post subject: |
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Ray White wrote: |
The two pumps are also in tandem.
Worth doing? or overkill? |
Paralleling the pumps will permit greater flow rate but I doubt that tht would be required with the XPAG. The 3½ litre SS Jaguar used this arrangement but I don't think it was even necessary there. Fitting the double contacts is well worthwhile though for reliability.
Peter _________________ http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon |
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ukdave2002
Joined: 23 Nov 2007 Posts: 4107 Location: South Cheshire
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Posted: Mon Feb 15, 2021 12:14 pm Post subject: |
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peter scott wrote: | Ray White wrote: |
The two pumps are also in tandem.
Worth doing? or overkill? |
Paralleling the pumps will permit greater flow rate but I doubt that tht would be required with the XPAG. The 3½ litre SS Jaguar used this arrangement but I don't think it was even necessary there. Fitting the double contacts is well worthwhile though for reliability.
Peter |
The AUA26 (in the pic) pumps can individually pump more than 8 gallons an hour, it would take a very thirsty engine to require 2
If the pumps were set up so that they worked in tandem they would be working against each other as it would be impossible to synchronise the phasing of the pumps action. Then if one did fail you would never know until the second one failed!
Dave |
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Ray White
Joined: 02 Dec 2014 Posts: 6324 Location: Derby
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Posted: Tue Feb 16, 2021 2:09 pm Post subject: |
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Sound like overkill to me.
One question... if a transil in the pump fails will it stop pumping? |
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ukdave2002
Joined: 23 Nov 2007 Posts: 4107 Location: South Cheshire
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Posted: Tue Feb 16, 2021 7:01 pm Post subject: |
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Ray White wrote: | Sound like overkill to me.
One question... if a transil in the pump fails will it stop pumping? |
They tend to breakdown o/c so you would never know they had failed, occasionally they fail s/c , but in this instance given their low current carrying capacity will probably fuse and go o/c almost instantly.
Dave |
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Ray White
Joined: 02 Dec 2014 Posts: 6324 Location: Derby
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Posted: Tue Feb 16, 2021 7:33 pm Post subject: |
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The reason I ask is I have some very expensive electronics which could be ruined so maybe it would be better if the pump just stopped working....
I suppose diagnosing such a fault would be technical.? |
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ukdave2002
Joined: 23 Nov 2007 Posts: 4107 Location: South Cheshire
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Posted: Tue Feb 16, 2021 9:06 pm Post subject: |
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When I worked for Sharp Electronics we reviewed MTBF (mean time between failure) for component failure; comparing manufacturers spec to real world failures. Small Zener diodes operating in the correct application have MTBF's measured in centurys!, so I don't think you have too much to worry about. |
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Ray White
Joined: 02 Dec 2014 Posts: 6324 Location: Derby
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Posted: Tue Feb 16, 2021 9:23 pm Post subject: |
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ukdave2002 wrote: | When I worked for Sharp Electronics we reviewed MTBF (mean time between failure) for component failure; comparing manufacturers spec to real world failures. Small Zener diodes operating in the correct application have MTBF's measured in centurys!, so I don't think you have too much to worry about. |
You have put my mind at rest, Dave. |
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Minxy
Joined: 22 Sep 2010 Posts: 272 Location: West Northants
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Posted: Fri Mar 12, 2021 9:04 pm Post subject: |
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With reference to the original post, when I worked for Audi sport back in the eighties building the works Audi Quattro rally cars it was standard practice to double up on many components. There were three fuel pumps, the car only needed two to run so if one dropped out there was always two to run the car. Two coils were standard on any rally car as was a second throttle cable strapped to the original. Double pulleys with two alternator belts were also standard
I don’t know about today but back then the driver and co-driver were expected to do run of the mill repairs so the car was equipped with spares such as rotors, caps, HT leads etc etc. We, generally, only attended the cars at service halts. _________________ Hillman minx convertible. Lanchester LD 10 |
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