Leaky carburettor

[Barnsey]

My C15 has been sitting around for many months while I have been doing jobs on it and now I want to kick it over, the carb is leaking.  When I tickle it, fuel gushes out of the tickler and won't stop. 

I removed the tickler, float and needle, cleaned and reassembled, but no joy. 

So where to go next?   I reckon I will remove the valve seat, and give it a bath in my ultrasound cleaner.   If this doesn't work I will be replacing parts.  But which first?   

Do I start with the valve?   Or might it be a heavy float?   Or something else? 

    BR      Ian



 

[rhyatt]

Make sure no washer under the tickler body

[Barnsey]

That is a good thought. Maybe there should be a washer and there isn't one, so the tickler is slightly lower than it should be. 

[bikerbob]

If you were not having this problem before the lay up then it suggests to me that the float needle is not shutting the petrol off, do you have a viton tipped float needle if not can I advise that you fit one they are far superoir than the originals. If that does not work then you need to adjust the float height this is acheived by fitting a washer or removing the washer under the float needle seating. the correct height is on the outside of the float cover you should see  a raised pimple just below the M in the word amal. To get this correct you need to either buy or make a clear perspex cover then place over the original cover and mark the height of the pimple onto the clear cover with a felt tip pen and then fit to the carb turn petrol on and it should rise to the level of the felt tip mark. This is assuming you have a monobloc carb fitted. If a concentric carb then fitting a viton tipped float needle still applies

[Barnsey]

I've opened up  the carb again, and it looks like the float is catching on the inside of the casting.  Yes, it is definitely labelled as a 376 float.  It is catching on the runner which has the screw thread in the end for the end cover.
This would only happen when the chamber is completely empty.  I will clean some of the corrosion off and see if it still happens.   Very odd tho'.  Is it a design feature or is something amiss? 

 Ian

[cdsdorset2]

Common fault. Especially if its a "stay up " float. Just dress tge casting with a fine file.

[JulianS]

The later made stay up floats are just a fraction smaller and marked part 376/083/1. The earlier versions marked 376/083.

The later made monocblocs come with the troublesome casting is machined to avoid the moulding mark on the float. You can just make it out in the photo.

original made monoblocs do not have a washer between float seat and body, it is a metal to metal joint. The later ones, which take the thin concentric flange O ring have a machined recess for a fibre washer. Using a washer in the carb without the recess results in the float resting on the tickler preventing it from closing the float needle and petrol pours out.

[bikerbob]

In the Amal catologue they list a Float level washer kit for monobloc carbs it consists of 4 aluminium washers of 0.15mm  0.25mm  and 2- 0.5 washers replacing the fibre washer with a series of diiferent combinations of these washers allow the user to vary the fuel level. Catologue ref  RKC/SHIM.  Burlen Fuels sells the kit for £5 including VAT

[Barnsey]

Woww! What a concise set of answers!

Infact cleaning the oxide off of the inside of the chamber with some wet and dry paper did the job, at least for now...

    Thanks,

           Ian