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Join Date: Jun 2011
Location: Tromsų, Norway
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Send a message via Skype™ to Einar Irgens
Zenith TIN 40 jet in bowl

Hi.

The pic shows the internals of one Zenith TIN.

At the bottom of the float bowl there is at tiny jet (1). I think it's supposed to feed the auxillary system (which I have removed) with fuel when you suddenly lift the throttle at high revs.



Further up there is an air jet (2) which i think is connected to (1). On the outside there is some sort of bolt (3) that I think is part of the same circuit. Can anyone confirm this theory?

Is there a simple way to blind this (sub)system completely off? Previously, I have sealed (2), but I want to be absolutely sure that no air/fuel circulates.

Einar

Old 05-10-2020, 08:04 AM
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That photo is a bit tough to see.

If you do a search you find the thread that explains tapping the pipes where the enrichment hoses connect and then using a cap screw with some locktite to seal them up.

That would address part of your goal.
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Old 05-10-2020, 12:39 PM
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#2 is Idle air correction jet
Old 05-10-2020, 04:16 PM
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Old 05-10-2020, 04:35 PM
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No, no. These are #2 and #3.



Sorry about the bad picture.
Old 05-10-2020, 10:34 PM
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I have one additional question. How do these come off? And how can the emulsion tubes stuck inside them be knocked or pulled out?


Last edited by Einar Irgens; 05-11-2020 at 01:34 AM..
Old 05-11-2020, 12:00 AM
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1, 2 & 3 are for delivering fuel to the emission-era "barnacle" that is attached to the side of the Zenith. #2 provides air to emulsify the fuel that is drawn through #1 and the #3 screw controls the rate of emulsified fuel delivery. The "barnacle" was activated during compression braking (throttles closed during deceleration) and a solenoid switch mounted to the flange at cylinder #6 that determined that the throttles were closed. Tighten screw #3 to de-activate this system from delivering fuel during deceleration. The idea was to add fuel during deceleration which was a lean operation (no fuel and lots of air) and lean running results in high nitrous pollution.

The brass bits in post #6 are the pressed-in brass tubes that house the emulsion tubes. Un-screw the main air correction jets at the top of these pressed-in tubes and the emulsion tubes will come out. Sometimes these pressed-in brass tubes will rotate when trying to remove the main air correction jets, hold them with pliers while un-screwing the air jets.
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Last edited by 1QuickS; 05-11-2020 at 06:52 AM..
Old 05-11-2020, 06:50 AM
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Thanks a lot, Paul. I have been wondering what the point of the system is. Does the Weber IDS have a similar system, in order to avoid backfire when closing the butterflies at very high revs? I guess I don't have to do anything, since I have already made sure no vacuum is applied to the system.

Regarding the brass pipes: I have taken off the air correction jets, but for some reason the emulsion tubes stay inside them no matter how much I shake the carbs. There is quite a lot of muck and carbon deposits inside the carburetors, every bolt and jet is sticking. Broke one of the main jets while unscrewing it.

Old 05-11-2020, 08:49 AM
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IDS Webers have a high speed enrichment device that provides a richer fuel delivery under high RPM operation, completely different from emission era Zeniths.

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Old 05-11-2020, 05:25 PM
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