Many MGs from the T type onwards had a metal heat shield which was clamped between the manifold and the carburettor flanges (I think the earlier ones had a woven asbestos backing), together with a block of heat insulating material shaped to the same profile as the carburettor flange. It should be easy to shape an aluminium sheet to fit in the same way, bending if necessary to stay clear of the exhaust.

Location: Just north of Cambridge

Thanks for the above suggestions. It's not often that heat affects the engine but on a recent run across Belgium and France the outside temperature was 34C. The petrol feed is by gravity from a scuttle tank and the pipe makes a curve in front of and above the exhaust down-pipe.

Location: Sussex by the Sea

34 is definitely on the hot side. If you've just got gravity feed for an SU there won't be much incentive for the petrol to keep the float chamber full, especially going uphill. A carefully hidden pressure pump may help. Plus I believe there's three different sized float valves for SU's, try the second size rather than the usual smallest one?

We travelled through Spain and France crossing the Pyrenees last summer in the Chummy, 5 up with a trailer in 40c heat. We suffered no vapouristion issues with standard Zenith on gravity feed.

I would suggest your issues lie more with the fuel feed as mentioned by Dave above - s/d carbs really need a pump of some sort to work properly, particularly when being tested on longer inclines.

I don't recall the F/B post mentioned by Sandy - apologies.

Since fitting a four-blade fan to my RP any problems regarding fuel vapourisation have disappeared. The car has a S/D SU and the standard engine driven T type fuel pump. Everything under the bonnet seems hunky-dorey when slogging up long hills although it does get a bit hot in the cabin especially when the ambient temp is over 32°C. I put this down to the greater air flow from the big fan.

The engine does take a little longer to reach operating temp on cooler days, but that's a trade-off I'm happy to accept.

When on the Euro tour going up particularly high and long pass my carb bowl was so hot that it could not be touched, the point where the carb meets the manifold had water droplets at the point of freezing. Definitely evaporation going on . Waited for her to cool down and finished the clump as in photo ( or at least what I hope will be a photo. Oh 1938 Opal , standard v26 carb

Location: Oakley, hants