After 2 recoveries in a week (with superb service on both occasions), be aware SU carburettor owners.
After nearly 70 years the brass float had the temerity to absorb fuel and sink. Unfortunately I diagnosed a worn shutoff valve seat and replaced with a viton tipped variant. There was a temporary reprieve until the pinprick holes finally allowed too much fuel in. Excellent service from Burlen Fuels, and now I understand the simplicity of the system. What i should have realised was that there were symptoms. Slight fuel smell and very slight moisture around the float bowl lid but not what i though was anything more than venting. For anyone with an SU keep an eye on the little issues and hopefully you won't let down your car.

It happened to me. I started my car and drove out of the garage but my niece told me there was a trail of water on the ground. It turned out to be petrol from one of the SUs through the overflow, absolutely pouring out and the engine was idling lumpily.

By coincidence Phil Glennerster visited me a few days later to check out my engine before restoration and he said it was a brass float sinking because of pinholes and that I should get plastic floats.

I couldn't find any plastic floats so I replaced them myself with new brass ones. Five years later they are still there. Phil didn't change them for plastic ones and I reckon they should last a few years more but I think ethanol corrodes them.

The following may be of interest - unsinkable floats, said to be ethanol resistant and E10 as well. I have intended to explore a bit more when/if I have problems, having had to replace some brass floats on my SP with my spare set when the originals started to fill up with petrol.
https://www.scparts.co.uk/sc_en/catalog ... m_campaign

Antony

Thanks for that info Mark, just realised my float must be 70 years old and will look out for that on my DB18 when back on the road. Just had fun drilling out head studs as seized solid due to one stuck valve!

I used some EGR spray to unstick the valves with head in situ, it seemed to work well, but if yours is apart that is probably a good time to lap them all in anyway.

Burlen were really good for original carburettor parts and do refurb kits specifically for each model.

Hi, it used to be possible to carry out a temporary repair on punctured Floats using a Postage Stamp, this was because on the old stamps, the adhesive was water based, therefore impervious to Petrol.
Of course the modern stamps will probably be useless !,,

Cheers A’l

I think I would have needed a whole book of stamps to stem the flow from numerous holes.

I had a similar problem on my 2.5 litre V8, which turned out ( when I examined them under magnification ) to be fatigue cracking of the brass float! I replaced them with the new ( and more expensive ) unsinkable floats and the difference it has made to the running of the car is extraordinary. Well worth the extra 20% or so