From cold, with the bonnet open, the front carb dashpot is cold (obviously), till engine warmed up
but as soon as the electric fan kicks in, the heat from the radiator is directed onto the
front dashpot, which starts to get warm, and this is with the bonnet open in a mild
Leaving the engine idling for 5 minutes and it is still the same, closing the bonnet
results in front carb and rear carb and dashpot heating up, (5 mins, ran out of time).
This is a very interesting subject, that I have been following closely. The hot air from the radiator can't be hotter than the engine but if it is mixing with heat from the exhaust manifold within the engine bay then it could be. The actual under-bonnet air currents are a bit of an unknown so there could be some interesting air currents swirling around the exhaust and over to the carbs. I would insulate the manifold, with a good quality bandage or get it ceramic coated. I did wrap my old 1850 exhaust and it made a massive difference to the under bonnet temp and made it run better too.
Does the electric fan rotate in the same direction as the belt driven one? With the electric fan pulling through the rad, does it pull so that it swirls the air in an anti-clockwise direction (when viewed from front of car)- i.e. from exhaust over the cam cover to the carbs?
It is interesting how much heat is there, the fan rotates clockwise when standing in front of the car, and instantly heats up the front float as soon as it cuts in.
I will put the louvred bonnet on, but the way the fan is directing the flow with the bonnet open, I can only imagine 4x worse when shut.
Getting the manifold ceramic coated is something I am going to do, namely because the rusted look is annoying, just need to choose a colour
also need a manifold to send off, taking off the one on the car is not an option at the moment.
Also got the temp gauge to go down a bit by changing the coolant today, most likely a bad mix ratio.