Lotus Elan

NPTF or BSPT ?

PostPost by: englishmaninwales » Sun Feb 19, 2017 10:55 pm

I want to replace the vacuum adapter on the No1 inlet runner with a plug (servo now removed). The adapter has a tapered thread, what size do I need and is it NPTF or BSPT?
Thanks.
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PostPost by: mbell » Sun Feb 19, 2017 11:44 pm

Perry certain Nptf, 1/8" maybe.

I did this recently and had no problem finding a plug in the US which I would have been harder for a bsp thread.
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PostPost by: Elan45 » Mon Feb 20, 2017 3:27 am

Because of the Ford link almost anything w/ pipe threads on the Kent motors have NPT. I believe the intake runner, vacuum tap follows this reasoning. Check the original Elan parts book; the code should tell you.

Roger
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PostPost by: rgh0 » Mon Feb 20, 2017 8:39 am

The ford bits have NPT threads but the Lotus bits ( e.g. head and diff housing ) have BSP threads as far as I know. Due to the small difference between the two especially in small sizes you can often satisfactorily thread an NPT fitting into the Lotus bits BSP threads

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PostPost by: englishmaninwales » Mon Feb 20, 2017 8:42 am

Roger, is the Elan parts book a resource on this forum, or elsewhere?
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PostPost by: englishmaninwales » Mon Feb 20, 2017 8:46 am

Thanks Rohan.
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PostPost by: alan.barker » Mon Feb 20, 2017 11:04 am

On Elan the vacuum "T" adapter on the No1 inlet runner is for the servo and headlamps.
On Elan +2 it is for the headlamps only with n?4 for the servo.
I think for me it's BSP ( the head is lotus not Ford)
Alan
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PostPost by: mbell » Mon Feb 20, 2017 3:19 pm

I fitted these:
https://www.amazon.com/gp/aw/d/B009IK28 ... ref=plSrch

1/8 ntp plugs. They seemed to fit fine and seal well enough that I believe they are correct but can't prove they aren't BSP threaded holes.

Measuring the removed factory take offs, 27tpi seems a slightly better/consistent fit than 28tpi. But again isn't conclusive.

Wide speculation but it maybe lotus went for ntp for these due to better availability of the one way valve take offs in ntp than bsp...
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PostPost by: wotsisname » Sat Feb 25, 2017 9:32 am

englishmaninwales wrote:Roger, is the Elan parts book a resource on this forum, or elsewhere?

If you search rdent . The website there has the parts manuals and the part numbers... Somewhere on here there's a list that helps decipher the part number
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PostPost by: ericbushby » Sat Feb 25, 2017 10:24 am

There is a good parts list on this forum.
Go to the top of the page, to -WIKI COMING SOON.
Most of what you want is already there.
Eric in Burnley
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PS. I just tried it and it didn`t work but it is usually OK
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PostPost by: ericbushby » Sat Feb 25, 2017 11:03 am

Oh, it works when I do it right !!!
WIKI COMING SOON
`WIKI` on choices
`shop floor` on dropdown list
then choose `workshop manual, parts list or others.
Cheers, Eric
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PostPost by: englishmaninwales » Wed Mar 01, 2017 6:06 pm

Well, as others have indicated, 1/8 BSPT fits fine, (although correct thread may be NPTF.)

Thanks.
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