Lotus Elan

Dellorto Pump Jet Filters?

PostPost by: RonR » Wed May 11, 2016 10:15 am

I'm just rebuilding a pair of Dellorto DHLAs for my +2, which includes changing from Vertical firing 50 Pump Jets to 35 Horizontal as recommended on here.

When the 35s arrived the jet holes were much smaller than the old ones, they looked like they could easily get clogged.

Then I noticed on the Dellorto diagram a small spring filter which fits in the upper part of the jet, Labelled 51 in the diagram, which my carbs didn't have:
Image

So my questions are:
Should I fit the filter springs when changing these jets?
Has anyone had these horizontal pump jets clog up with or without the filters?
If so, do I need to increase the size of the new jets to allow for any filter pressure drop?

Cheers,
Ron
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PostPost by: William2 » Sun May 15, 2016 4:39 pm

My carbs were also missing these filter springs so I phoned Eurocarb the main agents for Dellortos and they told me that the springs aren't necessary. I am therefore not going to fit any.
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PostPost by: RonR » Mon May 16, 2016 9:58 am

Thanks for the info William.

Were your carbs originally fitted with horizontal firing pump jets?
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PostPost by: William2 » Mon May 16, 2016 4:03 pm

Hi Ron, no my carbs were fitted with vertical pump jets as per the exploded diagram but without the spring. I invested in Des Hamill's book which I would recommend. Cheers, William.
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