I have always been of ther belief that vapour lock was when the fuel in the fuel pump boiled, causing only gas to pass into the carb.
One possible fix is to use the fuel filter that was used on Valiant 6's This was placed AFTER the pump & had a small, metered secondary outlet on the top face. This allowed some fuel to pass through the pump at all times & helped to keep the pump "fuel cooled" The fuel that was bled off was returned to the tank. It also allowed any vapour from a heat soaked pump to jet straight back to the tank.

If you give it a try, use it in conjunction with any other method that may be advised, including the use of a Bluebird electric pump at the rear.
I run a triple row radiator in my 200B & even with the AC on, no problems.
Chris

funny you shoul dmention wraping the fuel pipes from the pump past the head, this has worked on three cars for me, my mini, vk commojore and the dato in summer till i reset the float in the carb..

How about a remote float bowl sitting on top of the A/C TX valve?
In the 60's in QLD it was common to wrap an insulator round the fuel line where it circuited the tappet cover just above that hot thing called a Head .
Funny how heat rises.
Sorry nothing sensible to offer, tis the silly season.

O.K. This is not a 1200 problem, so I apologise in advance.

The temperature in Melbourne in the past few days has been unseasonably high and the daily driver 200B ( bog standard except for the 32/36 Weber) has been suffering from vapour locking under power.

I reckon that the under bonnet temperature is too high and the fuel is boiling in the float bowl, worse still when I use the aircon.

Has anyone else had this problem, and what is the best fix??

All contributions will be examined with my thanks.

Merry Xmas to all our members and correspondents.