scoop
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| posted on 20/9/10 at 08:02 PM |
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Webber Alpha carbs
Just been out in a very nice orange Westie out my way for a blat after looking at his webber carbs. Having looked at them and not being that familiar
with them i was surprised to see that there isnt much to adjust but now have a couple of questions about them.
Firstly the metal gasket between the carb body and the inlet manifold is loose dispite the nuts being tight. Is something wrong there?
Secondly the carb for 3 and 4 flows more air at idle and at 2000rpm the difference is even greater.How do you adjust that and is that normal?
Cheers, Steve.
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interestedparty
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| posted on 20/9/10 at 08:52 PM |
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I don't know a lot about Weber carbs, but I do know the bits you are referering to are called "Thackeray Washers" or something
similar, and are there to stop the carbs being affected by the vibration of the engine.
The difference in air is sorted out by adjusting the throttle linkage.
As some day it may happen that a victim must be found,
I've got a little list-- I've got a little list
Of society offenders who might well be underground,
And who never would be missed-- who never would be missed!
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scoop
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| posted on 20/9/10 at 09:28 PM |
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Thats good news on both points then. The throttle linkage was the only thing that made any difference for us but it was very sensitive. A quarter
turn was too much!
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Xtreme Kermit
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| posted on 20/9/10 at 10:05 PM |
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Webers are sensitive creatures 
1/4 turn can make the difference between being sweet and mahoosive pops and bangs... (don't ask me how I know) 
This I what I have for the mountings.
http://rallynuts.com/motorsport/MISAB_Plates_2323/
[Edited on 20/9/10 by Xtreme Kermit]
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scoop
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| posted on 22/9/10 at 08:37 AM |
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I cant believe so few people on here have webers or are willing to help out on this one, unless 'interestedparty' is correct
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interestedparty
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| posted on 22/9/10 at 10:24 AM |
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quote:
Originally posted by scoop
I cant believe so few people on here have webers or are willing to help out on this one, unless 'interestedparty' is correct
What is the actual question, maybe people are missing it, (I certainly am)?
Generally speaking though, if you don't know a lot about Webers in general, and that particular set-up, the best (only) answer is a rolling road
that does. It might well cost £150 ish for a couple of hours, but it will be worth it.
As some day it may happen that a victim must be found,
I've got a little list-- I've got a little list
Of society offenders who might well be underground,
And who never would be missed-- who never would be missed!
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Barksavon
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| posted on 22/9/10 at 08:12 PM |
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I had twin Dellorto Dhla 40's on my engine which are similar to twin webers i believe. I had Misab plates fitted between carbs and manifold
which are metal plates with a circular rubber gasket, it is intended to stop the carbs vibrating which can result in the carb bodies cracking or the
fuel frothing. If you hve thackery washers fitted then they shouldnt be tightened to the point that the 'coils' of the washer are
completely closed up but i dont think the misabs should be 'loose' either i would think you will be risking sucking air into the inlets if
they are. As far as airflow is concerned i think ive read that you should take the readings from the inner choke of each carb, that would be 2 and 3 i
think, and get them balanced up.......
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MikeRJ
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| posted on 23/9/10 at 04:17 PM |
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quote:
Originally posted by scoop
Having looked at them and not being that familiar with them i was surprised to see that there isnt much to adjust
There are numerous parameters to adjust on Webers, but most are adjusted by replacing jets with different sized ones rather than twiddling screws.
Carb balance is adjusted by the linkage between the two carbs, and yes 1/4 of a turn will make a big difference!
The gasket between carb and manifold will probably be a Misab
plate. There are supposed to be gently clamped in order to create a good seal but still allow movement, which is why there will either be spring
shaped washers (Thackery washers) or rubber bushes and steel cups between the carb flange and the manifold nut. It's a good idea to check the
Misab plates if you suspect any leaks; I have seen cheap copies where the bonded O ring has parted company from the plate and caused a leak.
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