Rover Sports Register Forum

In case sometime in the future you open the carburetor again, make sure that gasket is undamaged and installed correctly. New gaskets are still available. Petrol overflow drain should not suck air.

Dave I am so very sorry that I did not reply sooner. No excuses, I simply did not see that I had a private message. In the end I did get it sorted and here is how. First I purchased a replacement second hand Solex ( now spare as I found that I did not actually need it ).
So how did It get fixed. First I purchased a large sonic bath together with chemicals and gave the whole thing a thorough clean (several times in fact) having disassembled every part including the so called untouchable parts. I replaced all rubber diaphragms. Fitting the unit back on the car I fitted a replacement spacer between the carb and the inlet manifold and refitted the carb and fuelled it up.
Fingers crossed I started the car with no trouble ‘but’ to my bitter regret the hunting problem at low revs when coming to a stop at crossroad was alas still there.
Why I tried the fix I discovered I have no idea other than pure instinct but here is the remedy I found. The P3 inlet manifold has a petrol drain pipe that is situated at the base of the manifold below the carb. On my car the pipe is missing but the nipple is in place. Removing it I found it is not a ‘non-return valve as I expected it to be, given the considerable advice received telling me the problem is definitely an air leak in the fuel/ carb system.
I started the car and I simply put my finger over the hole where I removed the nipple and hey presto, perfection. I fitted a cap on the nipple and fitted it back thereby blocking the fuel drain. I have run the car all summer with no slow running idle problem.
This fix begs the question why the fuel drain is there? I hope if you have the same problem that this helps. Not sure I will ever use the spare Solex but it can go with all of the other parts I appear to be accumulating! Best wishes EastEndJohn. Scotland

I have the drain tube fitted to my 75 and I don't have the hunting problem. It is there to drain fuel from the manifold if it floods. Maybe it needs the tube fitting as the open end will be a lot lower than the manifold?

As others have said, the drain is there to prevent a flooded carb from flooding the engine too. Mine was blocked off. Being a perfectionist, I bought a length of copper capillary tube and soldered it in place, routing the 600mm of pipe through the supporting bracket attached to the oil pan.