MGB Carburetor Conversions and Upgrades

SU, Weber and Zenith Conversions

This web page was compiled by Andrew Yue.

Click here to return to my MG Home Page.

Original carbs on any car will eventually wear out making for subpar performance
This page contains the some options for 1975 or later MGB owners wishing
to improve performance by replacing the stock single Zenith/Stromberg set up.

Let's start with removing the original single Z/S factory set-up
that used a dodgy combined intake and exhaust manifold assembly.

Above is a single Zenith conversion done by Barry Kindig in California.
He did away with the restrictive factory combined intake and exhaust manifold.
The simplicity of the design is a joy to behold.  That's the worlds biggest heat shield.

Picture above is Barry's own intake manifold design,
along with a readily avaiable exhaust header type manifold.

The result is a design that allows the engine to really breathe,
which allows for a more fuel and air to reach the cylinders at wide open throttle.
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Installing SU Carbs

In contrast to the simple design above, I opted to install the
stock dual SU carburetors found on the 1970 and earlier MGB's.
 

Things begin to look a tad more complicated,
because of the extra plumbing involved.

What you wind up with, in addition to two idle screws,
two choke and throttle linkages to set up, is two hoses to
everything to include the fuel inlets, float vents, and PVC hoses.

The later SU manifold allows for the use of the original vacuum
take-off for the power brake booster that was added in 1975
and if desired you can keep the original smog pump.
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The Weber DGV Conversion

Things begin to look much simpler in this image.

This is Wayne Kube's 1979 MGB with a Weber DGV installed.

This car shows a meticous degree of detailing by the owner.
Notice that the fuel inlet on the front of the carb has been reinstalled so that the fuel line is directed towards
the fender rather than toward the hot exhaust manifold as is usually the case on a Weber installation.

The Weber downdraft is a proven two barrel carb with progressive throttle butterflies. The carb is easy to set up, reliable
and delivers good fuel mileage. It fails to deliver the low end grunt that is available with a pair of SU's
which is more noticeable in city driving where low rpm driving situation are the norm.

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Below is a second example of a Weber DGV installation neatly done on an 80 MGB.

This 1980 MGB owned by Jimmy and Jonie Lawrence of Lufkin lacked nothing.
It even has an A/C and an electronic cruise control.

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Finally the veritable Weber Sidedraft.

The carburetor upgrade for the true enthusiast.

This 79 MGB belongs to Ron Shimek of Austin, TX.


This Web Page was last modified on 4/5/2001