Carburettor float levels

[Bob King]

What is the correct float level for B32PBI_6 carbs on a D2 engine? Geoff Dowdle says 16mm from the top of the float bowl and I will follow his advice unless anyone has views to the contrary. Strangely, neither the handbook or the workshop manual address this subject.

[AC Ace Bristol]

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Bob
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Checked through my Solex manual, Bristol and AC manuals , Not a single mention or guide to setting the  needle valve to float level .

Tony Byford rebuilt and maintains my  Bristol engine !00D664 ( upgraded to D2 spec with compression 10.2 :1) he always sets the float levels by using a home made aluminium setting gauge.
Invert the Solex carburettor top and  measure and set the Needle Valve ( Nv) to the same as the thickness of his home made aluminium gauge.

I have spoken to Tony and he will confirm measurements tomorrow morning,  We will confirm dimensions  later tomorrow..

All the engines built and maintained by Tony Byford are set up accordingly and have never experienced any problem other than if the needle valve vibrates and
rotates  in which case it would no longer cut off the fuel supply to said float chamber. 

Cheers

Keith

[Bob King]

Thanks Keith. On Geoff Dowdles advice I made a main jet holder with copper tube soldered in and then clear plastic tube in which I can measure the level of the fuel in the float chamber.

[AC Ace Bristol]

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Bob

Would be interesting to see if The  Geoff Dowdle method you refer to with the copper tube and plastic tube gives the same result as Tony Byfords method.  Just one thing,    I believe Geoffs metod should read the smaller Gs  Starter Petrol  Jet not the main Jet Gg .

Tony's method is  to invert the Solex Carburettor top, Screw in the needle valve ( Nv.)   place a flat edge across the face and the needle valve should close off the fuel supply at 3.3mm  (Tip of valve to face of carburettor top.   If the fuel doesn't stop flowing  then a thin aluminium washer should be used to bring the needle closer to the float to  ensure the needle valve closes fully.
Tony's method is quicker and simpler, However  both methods produce the same result, that of stopping the flow of fuel to the float chamber.
Solex Manual and other workshop manuals do not give a figure as  correct authentic Solex  components  should give correct setting  to work from the day the carburettor left their factory.

If anyone has used both methods it would be great to learn if they give same figure / result.
Tony's method has been well proven for 30years or more with Bristol engines in Ace, Acea, Greyhound ,Cooper Bristols and Arnolt Bristol. ( Race & Track. )

Any feed back appreciated.....

Keith

[TTM]

Hello,

Geoff's method does use a modified main jet holder (Gg). He made one for me but I have still not taken the time to use it. Perhaps I am a little ham-fisted but measuring the level of fuel in the plastic tube with the engine idling does not seem exactly straightforward to me.

[Bob King]

I guess the proof of the pudding is in the eating. We set the float levels to 16mm using the GD method with good effect. TTM, the measurements were taken with the engine silent - I have an electric pump, which helps. A piece of steel bar was rested across the air intake of the carb and the plastic tube taped to it. then relatively easy to measure the level with rule or vernier.

[TTM]

Well Bob, I understood from what Geoff said that the engine needed to be running.
However, as my car also has an extra electric pump that I use only to prime the circuit before cranking and if you say that a static measurement works then I will give it a try. Thank you for your feedback.