Vacuum pipes

Talk about the E-Type Series 3

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dpugh
Posts: 16
Joined: Wed Aug 31, 2011 8:25 pm
Great Britain

#1 Vacuum pipes

Post by dpugh » Fri Sep 06, 2019 8:42 am

This is UK RHD 1973 car

I am trying to improve the running idling. The car tends to vary the revs at idle. Not dramatically just a few hundred revs. I am looking for vacuum leaks, reading I am getting myself a bit confused.

I believe I have vacuum retard with vacuum unit on the dizzy pointing towards the back of the car. The pickup for the pipe is pointing towards the dizzy.

Rather than from the bottom of the LH rear carburettor the vacuum retard is connected to the rear of the LH inlet manifold. This looks original rather than a later modification. The pipe under the carburettor is unplugged, shouldn't this be plugged?

Also the bypass valves are not connected to the vacuum and just left open. Shouldn't they be either plugged or connected to the vacuum?
Dave

1973 OTS S3 Manual UK spec
1972 2+2 S3 Manual UK Spec (In bits for a long time...too long)

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MarekH
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Location: Surrey
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#2 Re: Vacuum pipes

Post by MarekH » Fri Sep 06, 2019 9:51 am

That's not original and it's wrong on every level.

Either plug the vacuum retard back in where it ought to be plugged into or blank off the lower left carburettor. Right now you sound as though you certainly have a vacuum leak where you don't want one and are needlessly retarding the ignition at more than just idle rpm.

Take a look to see whether the bypass valves are blocked off internally. If not, then either repair them and connect them up as per the instructions in Buckeye Triumph Stromberg web pages or leave them blanked off. They don't achieve anything useful except during overrun anyway.


kind regards
Marek

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Topic author
dpugh
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Joined: Wed Aug 31, 2011 8:25 pm
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#3 Re: Vacuum pipes

Post by dpugh » Fri Sep 06, 2019 12:50 pm

Thanks Marek
Dave

1973 OTS S3 Manual UK spec
1972 2+2 S3 Manual UK Spec (In bits for a long time...too long)

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dpugh
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#4 Re: Vacuum pipes

Post by dpugh » Fri Sep 06, 2019 2:23 pm

Just thinking, the top pipe at the moment is connected to the vacuum retard which I will be moving to below, but what is normally connected to this outlet?
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Dave

1973 OTS S3 Manual UK spec
1972 2+2 S3 Manual UK Spec (In bits for a long time...too long)

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MarekH
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#5 Re: Vacuum pipes

Post by MarekH » Fri Sep 06, 2019 3:25 pm

The s3 Parts Manual has all of the factory combinations listed. You can find a copy in the knowledge base elsewhere on this site. Many of the ports will simply have been blanked off as some will have been for an automatic car, others may be for legacy items as the manifolds won't have changed even though their usage has, depending on market and time.

kind regards
Marek

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dpugh
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#6 Re: Vacuum pipes

Post by dpugh » Fri Sep 06, 2019 5:50 pm

Thanks understood, I am guessing is was for the automatic vacuum pipes 26.10 and mine is a manual. So I will be blanking that off.
Dave

1973 OTS S3 Manual UK spec
1972 2+2 S3 Manual UK Spec (In bits for a long time...too long)

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