40 dcoe fuel problem

[checkrail]

Hi all, +2 with type 31's / mechanical fuel pump with hand primer / standard Airbox.
A few weeks ago starting from cold it ran on 3 cylinders, no. 4 plug had oiled up badly, swopped it for a spare and then gave the car a good run. It was perfect back to normal. However I noticed some fuel at the base of the Airbox below no. 4 trumpet,
This week I decided to try the carb cold starters I had never used them before but always checked that were shut off. They made no difference, I took the tops off the float chambers and the back carb had grit in the bottom which I assume had come from the cold start. I have cleaned everything and checked all the jets.
With everything back today I tried to start but the plugs oiled up and fuel was dripping badly below the Airbox.I swopped the plugs still no luck but got a loud backfire.
The carbs are set correctly with newish needle valves/ the floats are brass with no leaks

I'm sorry this is long winded but apart from that no.4 oiling up what's causing the problem with the fuel leaking. I look forward to any comments John

[Donels]

Fuel can get behind the chokes and leak out into the air box. Seal the chokes with a small ring of silicon on the choke mounting face.

[checkrail]

Have you any recommendation for the silicon brand?
Thanks John

[Donels]

I just used common or garden clear silicon. You don’t want to glue them in place, you just need to provide a flexible seal.

[checkrail]

The Workshop Manual has an amendment showing sealing with Hylomar, I have ordered some new 'P' clips as venturies on 3&4 were not very tight.
Thanks for your info. John

[prezoom]

On the "P" clips. In stock condition, they do not provide enough pressure on the aux venturi to seal it to the carb base. I found using an arch/hole punch to cut a small disc of some flat rubber, the same size as the hole in the "P", and placing it in the hole, will provide more than enough pressure to seal the aux venturi. They are now tight enough, that to remove them is a chore. I made a fork like hook to assist in pulling them out of the carbs

[checkrail]

Thanks for that idea

[SENC]

I apply a light swipe of EZ-Turn around the collar of the AVs to prevent air/fuel leaks here. Also use it on the idle bypass screws to eliminate air leaks around the threads. It is a fuel lube that stands up to higher octane fuels, and I'm more comfortable using it over silicone and other sealants where it could get sucked into the intake.