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Dual Weber Downdraft Carburetor problem.

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Dual Weber Downdraft Carburetor problem. #1
U of H Guy Nathan Wilson Houston, TX, USA Sign in to contact	Topic Creator (OP) Nov 25, 2015 07:47 PM Joined 8 years ago 6 Posts

My car runs fine at low speed, but under heavy acceleration it seems to choke out and feels like it is struggling to get up to speed. Please help if someone knows what might be the problem. Thank you.

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Re: Dual Weber Downdraft Carburetor problem. #2
Beedapox David Terry Tomball, TX, USA Sign in to contact 1976 MG MGB "My Little Blue Friend" 2020 Jeep Gladiator "The Blue Jeep"	Dec 1, 2015 08:11 PM Top Contributor Joined 13 years ago 739 Posts

When was the last time the car was tuned up (valves, timing, etc)? FWIW Weber DGVs have somewhat of a reputation for a "flat spot" on acceleration. I cured mine by adjusting the floats.

1976 MGB Roadster with Factory Overdrive
Weber DGV / Pierce Manifold & Tourist Trophy SS Exhaust
Schlemmerized Lucas 25D Points Distributor
CS130 Alternator
Replacement Brake MC (DOT5)
Replacement Lockheed Clutch MC and Slave (DOT5)
Hardi fuel pump
Aftermarket ejection seat

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Re: Dual Weber Downdraft Carburetor problem. #3
U of H Guy Nathan Wilson Houston, TX, USA Sign in to contact	Topic Creator (OP) Dec 1, 2015 09:50 PM Joined 8 years ago 6 Posts

I thought the mechanic would have after rebuilding my Heads, but I have someone else look at it here this weekend.

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Re: Dual Weber Downdraft Carburetor problem. #4
U of H Guy Nathan Wilson Houston, TX, USA Sign in to contact	Topic Creator (OP) Dec 6, 2015 09:57 PM Joined 8 years ago 6 Posts

Well I went to the AAC game instead, and we won. Stormed the field though!

20151205_142635.jpg 54.3 KB

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Re: Dual Weber Downdraft Carburetor problem. #5
rficalora ROB FICALORA Willis, TX, USA Sign in to contact 1976 MG MGB V8 Conversion "MG MUTT"	Moderator Dec 6, 2015 09:59 PM Joined 18 years ago 2,860 Posts

Valves have to be adjusted after the head is reinstalled. It isn't hard to do yourself. Here is a John Twistvideo on how to do it (John does a lot of great videos on proper maintenance)...

If the car sat unused for a year, the carbs may need to be rebuilt too. There are very small passages that the fuel goes through and they can get partially blocked by varnish when fuel evaporates.

But, first try replacing your fuel filter. A a clogged filter can let enough thru at idle or slow speeds but bog down or even make the engine die at higher speeds.

Also check your air filters while you're at it.

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Dual Weber Downdraft Carburetor problem.

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