Weber Idle Adjustment Problem - Page 3 - Alfa Romeo Bulletin Board & Forums
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post #31 of 76 (permalink) Old 02-21-2019, 02:23 PM
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Hello everyone is a long time that I do not step through here. I use google translate because unfortunately I do not know English well so forgive me if I do not write correctly. Thank you
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post #32 of 76 (permalink) Old 02-21-2019, 02:27 PM
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I would love to live near gordon to visit him but unfortunately I'm on the other side of the world.
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post #33 of 76 (permalink) Old 02-21-2019, 02:31 PM
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I have the same situation. by acting on the mixing screws nothing happens almos.
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post #34 of 76 (permalink) Old 02-21-2019, 02:34 PM
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sorry but I want to show you a picture and I have to get to 10 posts
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post #35 of 76 (permalink) Old 02-21-2019, 02:37 PM
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I am a person who reads a lot and writes little
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post #36 of 76 (permalink) Old 02-21-2019, 02:40 PM
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carburetor mounts are new, I tried to do as gordon says and take off the lead to see if they are dirty but look clean.
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post #37 of 76 (permalink) Old 02-21-2019, 02:45 PM
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I tried with the vacuum gauge to synchronize the carburetors and the situation does not change more than that.


what should I do?
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post #38 of 76 (permalink) Old 02-21-2019, 03:15 PM
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Giacomo2000 can you specify if all mixture screws have no effect or just one?

Judging by the vacuum readings (i've never used that specific syncronizer) I'd say you at least are out of sync, and at most dealing with some air leaking in as each barrel looks pretty different. Can you start by removing the progression hole covers and checking with a flashlight to see if the butterflies open at roughly the same time?
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post #39 of 76 (permalink) Old 02-22-2019, 03:20 AM
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practically you definitely the cylinder 2 I can not get it down and the cylinder 4 I can not get it up. The butterflies are properly aligned, I'm sure of this.
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post #40 of 76 (permalink) Old 02-22-2019, 08:10 AM
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If the butterflies are aligned and your vacuum reading is very off, that leads me to believe you have an air leak on the mounts or the intake manifold. For Cyl 4 always check the brake booster one-way valve and hose for dry rotting, and to make sure the booster is not leaking air you can remove the hose from the booster and plug it with something (something that won't get sucked in, obviously).

Does anyone know how accurate the meter being used in the photo is? I've only used the one that measures air flow and is placed on the mouth of each carb barrel...

Giacomo2000, was this vehicle running properly before you tried to tune it? Or are you working on getting it running and ran into this.
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post #41 of 76 (permalink) Old 02-22-2019, 08:11 AM
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Have you run a cylinder leak down test, checked valve timing and clearances? Any engine with variable cylinder volume fill will never have uniform manometer readings.


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post #42 of 76 (permalink) Old 02-22-2019, 08:19 AM
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Thanks Gordon Raymond
do you think it does not depend on the carburetors? the engine was completely rebuilt 4000 km ago. I performed the compression test and all the cylinders have the same value.
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post #43 of 76 (permalink) Old 02-22-2019, 08:38 AM
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thanks Zuker81
the car sucked air from the carburetor supports. I proceeded to replace them with the necessary gaskets. I tried to detach the booster but it does not change the situation.
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post #44 of 76 (permalink) Old 02-22-2019, 08:52 AM
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Quote:
Originally Posted by Giacomo2000 View Post
good morning to everyone
I have 40 Dcoe 32
I have a similar problem I think. I rebuilt the engine 700 km ago, I tried to synchronize the carburetors but the air screw for the third carburetor that is screwing unscrewing it has no effect. The carburetors mounts and all gaskets, valves, etc. all over again

What could be?

I hope it is understandable what I wrote
Thanks very much
it's a problem that persists in fact already in 2014 I ask for help from you. Now I have taken the car and I want to use it and to fix even the small problems that arise, starting from thi
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post #45 of 76 (permalink) Old 02-22-2019, 08:53 AM
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Yes, MUCH does depend on the Webers. Uneven readings with a >not-just-rebuilt< but KNOWN sound engine (tested) indicates either air leaks, or poorly closing butterfly plates, worn butterfly bars, seals bearings, bent or twisted bars, or combinations of the above. Most often combinations of worn or unsealing plates and damaged or worn bars. Most Weber DIY builders do not understand how to disassemble and reassemble these components correctly, resulting in issues of air leaks, and in some cases, damaged throttle bores from poorly set plate wear.
With vacuum readings from a manometer, you must KNOW that each lead reads the same, with the same vacuum. You must KNOW that each cylinder is pulling the same air volume. You MUST know Weber build is 100% correct. You must KNOW there are no air leaks.
Given that knowledge, it's very easy to pinpoint the problem area.
I hope this is helpful.
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