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Discussion Starter #1
hello what is the difference between weber emission carburetor (newer type) vs the old types?

I know the new ones got Venturi balance adjustment screw and some other jets and emulsion tubes but is that it?

can i rebuild a newer type and use the parts from a older one? like jets and emulsion tubes?
 

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I can only speak for Dellortos.
The emission version has a different way of switching between idle and main jets as the revs increase.
Also more progression holes.
You can use the same type of jet (apart from the idle jet tube which is different and not adjustable) but the values would be different to the non-emission version.
I don't know if webers are similar?
 

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I have 138/139 which I suspect are emission and they work just fine as they are. I suspect they take a bit more setting up but once done they showed no problems on the rolling road. Are you having problems with them?
 

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I think there's some confusion in a couple of the replies.
I am assuming that the type you have are 151's, or maybe even 149's, 44/45's ?
You need to give us the Tipo number.
If they are any of the above, the parts from the older carbs are directly interchangeable, ( except you will have to drill holes through all 4 chokes for the additional air screws to go through), and the only other thing that the "emission" carbs like , different to the older types, is a size higher on the idle jet, so you can swap all the chokes and jets from your older Alfa Weber carbs into your new set, you just may find they need a different idle jet, so if you're currently running 50F8's, you may find that they need a 55F8.
I buy, restore and sell DCOE's as part of my one man business, and have been using them for 40+ years.
I have run 151's on my 3 Alfa's over the last 8 years, and they all needed a bigger idle jet , everything else remained the same .
DCOM's are quite a different animal, more like the Dellorto in operation.
 

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Discussion Starter #6
I think there's some confusion in a couple of the replies.
I am assuming that the type you have are 151's, or maybe even 149's, 44/45's ?
You need to give us the Tipo number.
If they are any of the above, the parts from the older carbs are directly interchangeable, ( except you will have to drill holes through all 4 chokes for the additional air screws to go through), and the only other thing that the "emission" carbs like , different to the older types, is a size higher on the idle jet, so you can swap all the chokes and jets from your older Alfa Weber carbs into your new set, you just may find they need a different idle jet, so if you're currently running 50F8's, you may find that they need a 55F8.
I buy, restore and sell DCOE's as part of my one man business, and have been using them for 40+ years.
I have run 151's on my 3 Alfa's over the last 8 years, and they all needed a bigger idle jet , everything else remained the same .
DCOM's are quite a different animal, more like the Dellorto in operation.
Thanks! i got the 80/81 tipo
 

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Then they are from an Alfetta, probably an 1800, don't think yhey were used on the 1600, but, all your internals from the older carbs are interchangeable, although you will have to use either F34 or 41' emulsion tubes in the later carbs. Also there's a chance that the idle jets may be the later style, the jets and holders are significantly different, and whilst you can use the older idle jets & holders in the newer carb, they tend not to work well.
Better to sell them and get some 151's.
Steve
 
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