Lotus Elan

Modern nylon 1/4" fuel line . . . with an olive?

PostPost by: Craven » Sun Jan 01, 2017 10:48 pm

I wonder if the capacity of the fuel pump would draw fuel on a larger diameter feed pipe.
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PostPost by: Sea Ranch » Sun Jan 01, 2017 11:40 pm

You mean that if the intake tube was too large, the pump might not function properly and generate the required output pressure/volume?
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PostPost by: StressCraxx » Sun Jan 01, 2017 11:58 pm

Craven wrote:I wonder if the capacity of the fuel pump would draw fuel on a larger diameter feed pipe.


The fuel pump is a diaphragm type positive displacement pump. The larger the diameter suction line, the longer it takes to fill the suction line and prime itself. It may be only a few seconds longer to prime, but as long as there are no vacuum leaks, it will prime. There is not any significant suction lift ~30cm to prevent priming from the pickup in the tank.
There is no cure for Lotus, only treatment.
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PostPost by: Sea Ranch » Mon Jan 02, 2017 12:05 am

Perhaps there's the other answer to why the factory line was so small diameter (apart from the factory's assessment that it was large enough to supply the carbs and a 1558cc engine): reduced priming time. :?:

Seems reasonable. Especially given the pump has no manual prime lever under it (I miss that).

Could be this is a(nother) reason not to "fix" things that aren't broken. :mrgreen: Or, as Jim Hall says on Jay Leno videos, "the law of unintended consequences" . . . :wink:
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PostPost by: vincereynard » Mon Jan 02, 2017 5:49 pm

Sea Ranch wrote:Okay, here goes . . .

Vince, nice idea about the copper olive. Where do you get such a thing?

Craven, that insert looks very trick. Where do you get such a thing? And thanks for sharing about your little chemistry experiment. Good to know. :)

Randy


Loads of them at the usual "auction" sites.
http://www.ebay.co.uk/itm/301998692226 or http://www.ebay.co.uk/itm/121299360929
Note the difference in colour.

Craven is spot on with the insert advice, essential with a soft walled pipe or it can simply crush and pull straight out.

You might consider using an isolator valve before the pump. Makes draining the tank easier / turn the fuel off to the drain the carbs / isolate a fuel leak etc Lots of reasons.

http://www.ebay.co.uk/itm/111642406930

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PostPost by: pharriso » Mon Oct 16, 2017 8:58 pm

For future reference Ray at RDEnterprises sells the correct olive & nut for 1/4" nylon fuel line, his part number is 026E0370Nut.
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PostPost by: vincereynard » Tue Oct 17, 2017 2:05 pm

What can I use to connect the 1/4" (nominal 6mm) (O.D.) nylon pipe to 8mm (I.D.) rubber fuel pipe? Or even 6mm rubber pipe. I obviously cannot compression on the rubber.

Somthing like 6mm compression one end and a male (horse tail) the other would be ideal.

I could push the nylon into 6mm OD rubber and convert from there but it seems a bit of a bodge.
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