what is a emmission weber - Alfa Romeo Bulletin Board & Forums
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post #1 of 109 (permalink) Old 06-28-2014, 05:10 AM Thread Starter
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what is a emmission weber

I've looked but have not found a definitive answer so here goes.... what is an emmission dcoe weber carburetor? Is there a difference between a dcoe 151 made in spain and one made in Italy? Some of what I gather is yes, there is a difference but looking at the parts list I don't see any difference. Thanks!

The passenger seat is 15 miles an hour faster than the drivers seat.

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71 Berlina in 2L restored driver
the ones that got away:
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1962 Giulietta Spider normale
1965 Giulia Sprint normale
1972 GTV
1974 GTV
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post #2 of 109 (permalink) Old 06-28-2014, 10:28 AM
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well I know for europe emissions carburettors for alfa romeo mid 70's onwards used carburettors with the fuel mixture adjusting screws setting "sealed" in a tamper proof tower.
For webers the mixture adjusting screws were sealed on the 40DCOE from 1978 onwards.
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post #3 of 109 (permalink) Old 06-28-2014, 11:19 AM
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There are several different variations of "emission" Webers from both Italy and Spain, excluding the DCOM. For DCOE's, 40 or 45 mm, the general rule is that those that look like those pictured below, both 40's & 45's, viewed from above, are NOT emission Webers. Non emission are easier to spot than "emission". Those that look different in some SMALL way such as the last pair pictured, may be a variation, of have some "emission" intended function. The last pair are NOT emission.
I hope this is helpful.
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post #4 of 109 (permalink) Old 06-28-2014, 06:03 PM Thread Starter
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Yes, thanks!

The passenger seat is 15 miles an hour faster than the drivers seat.

currently
2017 Giulia Q4
74 GTV restored daily driver
71 Berlina in 2L restored driver
the ones that got away:
1959 750 series Giulietta Spider Veloce
1962 Giulietta Spider normale
1965 Giulia Sprint normale
1972 GTV
1974 GTV
1974 GTV
1977 Spider
1974 Spider
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post #5 of 109 (permalink) Old 06-28-2014, 06:22 PM
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Send me an e-mail if you would like to see some of the emission variations. I do less restoration work on those, but do often upgrade Spanish variations.


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post #6 of 109 (permalink) Old 06-29-2014, 01:55 AM
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As a general rule, factory fitted 40 DOCEs with suffix numbers 72/73 and higher are emission carbs. The aftermarket 151 is also an emission carb.

Jim

Series 2 USA 1750 GTV (in Series 1 European clothing)
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post #7 of 109 (permalink) Old 06-29-2014, 04:53 AM Thread Starter
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Interesting, what makes an emmision 151, I guess what I'm asking what is different between say a 32 and a 151? If Pat Bradon mentions "emmision" carb in his book I didn't see it. The listings for Alfa webers show a 32 and the same jets which allow a 151 to be jetted as a 32. When they are, are they still different?

The passenger seat is 15 miles an hour faster than the drivers seat.

currently
2017 Giulia Q4
74 GTV restored daily driver
71 Berlina in 2L restored driver
the ones that got away:
1959 750 series Giulietta Spider Veloce
1962 Giulietta Spider normale
1965 Giulia Sprint normale
1972 GTV
1974 GTV
1974 GTV
1977 Spider
1974 Spider

Last edited by gigem75; 06-29-2014 at 05:03 AM.
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post #8 of 109 (permalink) Old 06-29-2014, 09:42 AM
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Interesting indeed. I would also like to hear differences between 151 and classic models.

Giulia Super "Biscione" 28th February 1969
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post #9 of 109 (permalink) Old 06-29-2014, 10:21 AM
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Yes, still different. The 151 and many other "emission " Webers have a pair of extra adjustment needles located over the throat barrels, (italian version covered with grey caps unless lost). They are fitted with very fine air correction needles before the butterflys in back.
In use, those over the barrels are used to get a rough air correction setting and locked down with provided 8 mm locking bolts, caps then reinstalled. The final idle air correction is done with the fine needles rearmost, with exhaust analizer.
To use these as you would old style DEOE32's, the needles over the barrels are competely closed, and all air correction at idle is done with the rearmost needles.
Now to add more confusion, there were at least three types of rearmost air correction needles. I call them coarse, medium and fine. They DO NOT interchange in different bodies as the bore holes through the throats are different sizes as are the seat designs. The coarse ones are the about 60 degree taper you see on DCOE2's 32's and most the rest. The medium have a much more tapered point and are seen in those Jim mentioned. The fine are actually a tapered needle crimped into the screw and very fine.
Obviously each requires it's own type of adjustment and "starting" number of turns out from seated.
This is a TERRIBLE oversimplification. I can get more technical, but for MOST use that's unnecessary. If anyone feels they want to address this in more complex terms, please feel free.
Now, some of the high numbered Webers, like those Jim mentions, also have a VERY NEAT self adjusting accelerator pump bleed-back or exhaust jet in the bottoms of the float bowls. The purpose here is to avoid pumping unnecessary fuel into the pump jets under different types of acceleration (light throttle tickle vs "FLOOR IT!"). It consists of a brass spring loaded piston valve, that with varing pressure bleeds back or exhausts more or less fuel from the pump. If you have these, (they work quite well) DO NOT lose any of the small parts! No replacements are available easily, and they do not easily convert to the older style ball ckeck bleed back jet.
There are several other less noteworthy variations with notched butterfly plates, butterfly plates with holes drilled through them, 2, 3, 4 and even 5 progression holes and the list continues. Most variations were application specific, but "emission" variations were not only application specific, but adjustable within that application for a cleaner idle circuit than earlier Webers. The use of emission Webers on performance engines is common, particularly with the 45 mm Spanish Webers. They can all be made to work just fine, though the emission type may require a bit more fine tuning work for some performmance street applications.
I did not want this post to get into unnecessarily complicated technical detail, so it IS simplified.
On the picture below, note the grey cap over the coarse air correction needle on my customers restored 40DCOE44&45 Webers for his 1600 Junior Z.
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post #10 of 109 (permalink) Old 06-29-2014, 10:59 AM
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Thank you Gordon for the excellent answer. What I have heard from local carb shop is 151's and 152's come from Spain with classic jetting, this made me wondering if they are copies of the classic modells. Obviously they are not.

Giulia Super "Biscione" 28th February 1969
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post #11 of 109 (permalink) Old 06-29-2014, 11:25 AM Thread Starter
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All I can say is, you gotta love the internet! No way I would have learned that from anyone around here. From what I take away from the discussion I gather "emmision" weber is almost a misnomer although I don't know what else you would call it, "modern" weber maybe? After all does anyone think that because they have a 151 it's going to pass the probe test?
The idle setup must work because my GTV has never idled as smooth as it does now. With 130 mains I read 10.9 -11 on the wide band @4000 rpm in 5th and no vibration due to detonation. I could obviously set my HP pump to give me the same numbers but when I did so I was way to rich everywhere else. Bottom line is my "modern" webers are passing plenty of gas with the 130 mains, driveability is seamless between idle and main circuit, and it goes like stink.

The passenger seat is 15 miles an hour faster than the drivers seat.

currently
2017 Giulia Q4
74 GTV restored daily driver
71 Berlina in 2L restored driver
the ones that got away:
1959 750 series Giulietta Spider Veloce
1962 Giulietta Spider normale
1965 Giulia Sprint normale
1972 GTV
1974 GTV
1974 GTV
1977 Spider
1974 Spider
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post #12 of 109 (permalink) Old 06-29-2014, 11:37 AM
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As I said, these "modern" Webers are just fine. Different, but fine. For total ease of set-up, nothing is easier than a 40DCOE2 or 45DCOE9, but the modern Weber is STILL infinately adaptable.


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post #13 of 109 (permalink) Old 06-29-2014, 11:49 AM
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Quote:
Originally Posted by Gasolina View Post
Thank you Gordon for the excellent answer. What I have heard from local carb shop is 151's and 152's come from Spain with classic jetting, this made me wondering if they are copies of the classic modells. Obviously they are not.
Hi, your local carb shop man isn't correct. 151's and 152's were made in Bologna long before the transfer to Spain. I have had many Italian 151's and 152's through my hands over the last 5 years.
Many people have perpetuated a myth that Spanish DCOE's are bad news, this is completely wrong !!

It is true to say that the castings on Spanish DCOE's aren't quite as "sharp" and clean as they used to be from Bologna, but in most other aspects, as Gordon says, they are just as good, (and in some ways better), than the older DCOE.

I have sold many pairs of Spanish 151's to Lotus Elan / Cortina, Alfa, MGB owners who are amazed at the difference in how the later 151's and 152's run, compared with their old, worn out earlier carbs.
Hope that helps,
Steve

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post #14 of 109 (permalink) Old 06-29-2014, 12:17 PM
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Hi Steve, Thanks for your comment. Glad to hear that there really is no reason to avoid "modern" Webers.

Giulia Super "Biscione" 28th February 1969
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post #15 of 109 (permalink) Old 07-01-2014, 05:35 AM Thread Starter
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Blasphemer!!!!!!!! SPICA HP pump to webers, I've always have been and still am a big fan of our mechanically injected Alfas but I'm also a big fan of pistons lasting more than 20k miles. I was forced to remove my pump and install webers due to a serious vibration problem at 4000rpm due to detonation. I could minimize the vibration/detonation by setting the sweet spot mixture at 4000 but it was way to rich everywhere else and the FCS was screwed out to the point it almost was falling out. There was no vibration during warm up to operating temp but when the oil warmed up the vibration would rear it's ugly head. I must admit the motor idles smoother than it ever has and man o mighty does she run. I haven't given up on the spica and will investigate further with my spare motor on the test stand I built. drastic action yes no doubt but busting ring lands off of two, yes two different motors is also drastic.

The passenger seat is 15 miles an hour faster than the drivers seat.

currently
2017 Giulia Q4
74 GTV restored daily driver
71 Berlina in 2L restored driver
the ones that got away:
1959 750 series Giulietta Spider Veloce
1962 Giulietta Spider normale
1965 Giulia Sprint normale
1972 GTV
1974 GTV
1974 GTV
1977 Spider
1974 Spider
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