Amal Mk I Concentric Float Level

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Amal Mk I Concentric Float Level

Post by b50root »

Amal Mk I Concentric Float Level

Of all the adjustments you can make to your Amal Mk I Concentric, the float level is
probably one of the most important adjustments. A lot of people believe the float levels on
the Concentric are set at the factory and do not need to be checked. Nothing could be
further from the truth. While it is true that float level numbers were not published for
several years after the introduction of the Concentric, now that we have the numbers it’s
very important to use them. This is especially true if your Brit bike has more than 1

The method of adjustment is as follows.
• Determine if the level needs to go up or down
• Heat the float bowl with mild heat. A hair dryer seems to work better and be much safer
than a torch
• To raise the fluid level, lightly tap the top of the brass float valve seat with a 0.375 inch
diameter drift, driving it downward a very small amount
• To lower the fluid level, lightly tap the bottom of the brass float valve seat with a 0.125
inch diameter drift, driving it upward a very small amount
• Recheck your setting per the diagram on sheet 2 of this article
• Each time you change the float bowl, float pin, plastic float, or float valve, the float level
must be checked and readjusted if necessary.
• If you disassemble 2 carbs in the same work area, do not intermix the float bowl parts.

Although the position of the plastic float is important, what we are really hoping to achieve
is a standardized fuel level within all the float bowls on the same bike. The real objective is
to achieve the same height on the surface of the liquid fuel in the float bowl, so that the fuel
can be the same distance from the throat of the carburetor. Therefore, if you are racing and
really want accurate carburetion, then the thing to do is to measure the fuel height and not
the float height. The correct fuel height is 0.170 to 0.240 inches below the bowl’s surface.
In most cases, the float height given on sheet 2 will result in this measurement, but when
racing it’s always best to check.

Hope this helps!

Richard Whatley
Suwanee, GA
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Joined: Wed Apr 23, 2008 10:56 pm
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Re: Amal Mk I Concentric Float Level

Post by ebsbury »

The dimensions of the Amal Mark 1 Float Chambers have changed over time.

Read this before you adjust the float level.
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