In the recent hot weather found my 2L Mk1 Vitesse, standard but with electric fans, very difficult to restart when hot if left for a short time but fine if left for an hour or so. Had moved a glass type filter from just after the tank to just before the carbs. moved it back and problem went away. After one run before moving it back parked car in garage when looking about five minutes later fuel filter empty of fuel and petrol in glass top pump boiling, an hour later filter full of petrol. A few utube videos with same restart problem stated restart problem due to very rich mixture, as above, some had gone to the trouble of fitting a filer vapour separater with a return line to the tank.
Regards
Paul