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vwinnovator
Samba Member
Joined: July 11, 2005
Posts: 1555
Location: Still doing it in the back of your VW
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 Posted: Wed Aug 24, 2016 4:04 am Post subject: horizontal brass tubes across venturi- weber 40IDF |
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got a set of 40 IDF's that have a horizontal brass tube running across the venturi side to side, parallel to the throttle plate.
some kind of booster fuel rail?
anybody know?
good / bad? |
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madmike
Samba Member
Joined: July 11, 2005
Posts: 5292
Location: Atlanta,Michigan
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| Posted: Wed Aug 24, 2016 4:22 am Post subject: Re: horizontal brass tubes across venturi- weber 40IDF |
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Hey Paul,It sounds like you have CB update kits in them,,some like them?
cheers,Madmike
_________________
'Black Ice'Drag Buggy 'Turbo'
Rail Buggy 1915 turbo
76 Drag/Street bug 2180cc 'Turbo' 11:85 @113 mph"If I go any faster I'll burn up the Hamster" ,gets 28 mpg. also 10/09/22 11.90 @115 mph
"If I'm ever on Life Support,UNPLUG Me, Then Plug me back In see if that Works" |
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old DKP driver
Samba Member
Joined: March 30, 2005
Posts: 4145
Location: Los Gatos,Ca.
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| Posted: Wed Aug 24, 2016 10:17 pm Post subject: Re: horizontal brass tubes across venturi- weber 40IDF |
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The horizontal spray bars seem like a nice upgrade along with all the other
goodies that come with the (upgrade kit) for the price.
Please, Let us know how they work out for you and also, could you post Your
specific use for them and,what size vents are in your setup.
CB shows 2 different kits for the 40 idf versus the 44 idf upgrade.
Chris
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V.W.owner since 1967 |
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modok
Samba Member
Joined: October 30, 2009
Posts: 26787
Location: Colorado Springs
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| Posted: Thu Aug 25, 2016 12:07 am Post subject: Re: horizontal brass tubes across venturi- weber 40IDF |
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They can work, and make power, but if the choices are good or bad I'd say....bad. Not very good signal, require HUGE main jets. in most cases a larger carburetor is the better way to go.
Torben has some great ideas about how to make them work better, which he shared a few months ago:
| Alstrup wrote: |
Another thing. a little late, but better than never.
The 40 IDF 70-71 has a relatively small inlet at the aux venturi, which limits the flow significantly. In fact even a 32 mm venturi does not get full benefit due to the restriction further up in the carb. It is very difficult to get much past 134 hp. On a couple of occassions I have maxed these carbs out as per customers request on large displacement engines.
I remachined the carb top so the inlet was 44 mm (then using a 44 mm Jenvey stack) and 41 mm at the bottom. Then i installed the CB carb upgrade kit. This way you get a clean shot of air down through the carburettor. With similar engines, maybe with a little better heads I have been able to pull 145 hp with the delivered 32 mm venturies and 150 hp with a set of homebrewed 34 mm venturies. the "funny" thing is that when I did this ALL the weired fuel distribution problems disappeared and they were about as easy to dial in as a set of Dells. Another positive thing was the torque increase in the midrange rpm.
With the 109 cam I would not reduce header size to 1˝". That engine needs to breathe.
This is an upgraded 36 Dellorto though, but you´ll get the idea.
These 36 Dells now support 131 hp with an almost perfect fuel curve.
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