I found a small screw

[Clampit]

I am about to rebuild my H1 carburettor with a new major rebuild kit. It’s the large
brass bolt that holds the bowl to the body that concerns me. I found a small screw
with washer that is a push fit (no thread) that sits inside the bolt as shown on the photo.
Why should this be needed ? burlen.co.uk say it should not be fitted. Any ideas

[panky]

The small screw looks like one of the three that hold the carb dash pot on to the main body of the carb.

[philthehill]

The small screw that you found should not be there (confirmed by Burlen) and should be thrown away.

How it came to be where it was is anyone's guess but I suspect it was dropped in there by accident. The screw in question appears to be one of the screws which hold the dashpot in place.

[simmitc]

Could also be the screw that holds the float chamber lid in place. Probably dropped by accident, and should be removed from where you found it.

[philthehill]

The H1 carb in question does not have the three screws holding the float chamber lid in place. It has a central stud in the float chamber around which the float rises and falls and the lid is kept in place by a female threaded capped nut which passes through the lid of the float chamber and screws onto the central stud.

I believe the screw and shake proof washer to be the one that secures the float chamber steady to the main body of the carb. The steady runs from to the top of the carb float chamber to the main body of the carb (just in front of the dash pot) where it is secured by the screw and shake proof washer..

[simmitc]

Agreed, but someone servicing carbs could be working on a number of carbs at the same time, and the screw could have fallen in from anywhere. The main point is that it shouldn;t be there.

[Clampit]

Well I agree it should not be there. I have wondered if someone placed it there to reduce fuel flow from the pump.
We will never know but as always thank you for your input.

[philthehill]

The screw if placed there to reduce the flow from the fuel pump would be ineffective as the flow from the pump is controlled by the float chamber valve and float. It may reduce the flow to the jet but if the main jet and the main needle are correct the carb will require a full flow of fuel not a reduced flow which could make the mixture weak leading to overheating of the engine and holes being burnt in the top of the pistons.
As you say - who knows.

[edd_barker]

Don’t throw it away though!! You never know...