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Author Topic: Webers...again!  (Read 748 times)
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welleyes
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Posts: 87


« on: 20 July, 2023, 10:53:59 AM »

We are just checking over a Weber with a view to putting it on the Aprilia. It was bought as having come off an Aprilia; as it is correctly jetted, we are sure that must be true. It seemed to be in good shape except that a washer had been placed under the accelerator pump jet with the result that the lid was held open about twelve thou even with a gasket under it. Fortunately, our engineering skills rose to the challenge and the washer was removed.

As the carb has been sleeved to the 32mm of the standard manifold, we assume that was done by or for Alperton. Does anyone know why Alperton used the Tipo 36 and sleeved it rather than using a smaller one as Lancia did in Italy? Was the 36 easier to get, cheaper or more desirable in some way that I cannot fathom? Incidentally, it is a bronze one, so could double as an objet dart. I feel sure that we will be pestering the forum with nave questions about the 36 DR5 SP before long. The number is 1714; if that indicates production of two thousand plus, what else used this carburetter?

Andy and Stuart Tallack
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welleyes
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Posts: 87


« Reply #1 on: 23 July, 2023, 07:44:37 PM »

I can venture a guess in reply to my own question!  There were not many single choke Webers with both an accelerator pump and the extra jet to provide more fuel at wide throttle opening by means of a jet opened by a needle beneath the pump piston. Perhaps they were used on early Alfa 1900 or 2500 cars and became redundant when they put twin choke Webers on. Who knows? Not me. It was obviously worth sleeving them.

To my great surprise, I have managed to cleared the internal drillings and the pump actually works. The two bad pieces of news are first,that the pump body is made from a zinc based alloy which was not intended to last for seventy years and second, that I cannot find any way to dismantle the pump as one spring seems to have been fixed so that it can only be removed destructively. If anyone knows otherwise, I would love to hear: I wanted to dismantle and measure it as I thought that it would be possible to fabricate a new and stronger pump body if I could measure it all.

If anybody needs it, I translated the German language description of the Weber Vergaser Typ 36 DR5 SP. Until I did that, I had no idea what the extra jet sticking out of the top of the carb was for.

Stuart
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GG
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WWW
« Reply #2 on: 23 July, 2023, 09:07:27 PM »

32 DR 7 SP were used on the two liter B20s. I think the number refers to mounting conditions, as a no. 3 and 10 have also been seen and are largely the same. Perhaps these are similar to yours.

Can email larger versions if anyone interested. Also posted on: http://www.lanciaaurelia.info/carburetors1.html


* Weber DCZ A gnl scrn.jpg (2096.19 KB, 931x1280 - viewed 34 times.)

* Weber DR B gnl scrn.jpg (1891.28 KB, 931x1280 - viewed 32 times.)
« Last Edit: 23 July, 2023, 09:10:30 PM by GG » Logged

B20 s.2, Appia C10, Flavia 2000
GG
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« Reply #3 on: 23 July, 2023, 09:09:01 PM »

32 DR 7 SP were used on the two liter B20s. I think the number refers to mounting conditions, as a. 3 and 10 have also been seen and are largely the same. Perhaps these are similar to yours.


* weber_dr_a_sml2.jpg (757.18 KB, 675x929 - viewed 28 times.)

* weber_dr_b_sml2.jpg (95.26 KB, 676x930 - viewed 33 times.)
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B20 s.2, Appia C10, Flavia 2000
welleyes
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Posts: 87


« Reply #4 on: 24 July, 2023, 06:35:21 AM »

Pretty well the same, but with the addition of accelerator pump. That confused me at first as it does not work the same way as the later Weber piston pump. It was an interesting exercise and just the sort of thing recommended to stave off the threat of age related brain fog!

Stuart
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