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obrut

Early Weber DCOE 40s

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I have a pair of DCOE 40s that I am cleaning and rebuilding.  I think I have early webers, I have brass floats and the spindle shafts have a small piece of leather with a spring and plug to seal them.  I'm looking at ordering these https://www.ebay.com/itm/WEBER-40-45-48-DCOE-CARBURETTOR-SERVICE-KIT-WITH-ADDED-SCREWS/263406094171?hash=item3d543a075b:g:HTkAAMXQaBRRi-yw:rk:5:pf:0

 

I have a 175 needle valve size, will that work for a mild L20B build?  If not I can order a different size when I order the kit.  Anything else I should look out for when ordering gasket kits?

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It doesn't look like they come with accelerator pump diaphragms. Those can tear upon disassembly, and they dry with age, so I might get a pair of those too.

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Don't think the early DCOE's had diaphram's. I've just been through the DCOE jungle and unless they are set up for your engine the gasket set is just the beginning of your time and expense. Unless you want great fuel economy they are worth it though.

 

Kurt 

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On 11/21/2018 at 5:43 PM, Stoffregen Motorsports said:

It doesn't look like they come with accelerator pump diaphragms. Those can tear upon disassembly, and they dry with age, so I might get a pair of those too.

None of the DCOE Weber have acel diaphragms, they use a brass barrel 

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it should have the revision number on the lids as well. they are all not the same. ideally you want matched revisions on the same engine. some people have ran mismatched carbs before with success, but meh.  internet reasoning dictates the old ones are good because the progression holes are drilled differently. what the difference is i dont know.  ive owned two dcoe's ever which i currently have and love.

 

http://www.s262612653.websitehome.co.uk/DVAndrews/webers.htm

 

check this out this link is gold and will get you real close.

using this site for a mild l20b your 40 config will probibly be:

34 or 36 mil venturi's but no smaller than 32 for sure. smaller is better for low end response but will start eating into your top end power.

f16 or f9 emulsion tubes, if its really hot rod maybe f2's but if its hot rod it should have 45's

145 main jet,190 air corrector

 

idle jet, maybe like a 55f8, i would get a 50 and a 60 too so you can tune to what it likes.

 

your float needle size will most likely be ok

 

buy yourself a redline jet pack based on this being the middle of the road (they offer a few different kinds) and you can get these dialled in very decently.

 

i used the info above to initially jet my motor, ended up going up just one jet size on the main jet and the idle then it was perfect.

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Thanks for the feedback, these supposedly came off a 510, here are the jets, chokes etc that are in them.

 

Choke 32

Venturi 35

Air 170

Emulsion F15

Main jet 125

Idle 45 F9

Pump jet 55

bleed back 50 - this is the one at the bottom of the bowl

 

Both carbs numbers are

TIPO 40DCOE18J

No  F.E.T.  7J

 

They came bolted to a L series cannon intake with soft mounts. 

 

Edited by obrut
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I bought the rebuild kits and a few other parts from the ebay link.  Unfortunately my note to the seller to include 175 needle valve didn't make it to him some how and I ended up with 150.  Is that going to be too small?  How do I know what size I should run?

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try it. i dont have information on the float needle sizes all i know is if you make shitloads of power or turbo you need the larger ones. these carbs will most likely be fine for you, maybe a little on the lean side but may be okay if your at a higher altitude?

once you get these on if it runs decent do a super long wide open highway pull (a minute+) and see if it starts crapping out. if it doesnt your needle valve size is probably ok. i dont even know what size mine have in them but im not having issues anyway.

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