The undertrays on Connie have been patched up so many times its hard to work out what the shape is supposed to be most of the time. These links are really helpful.
I can also confirm that the airflow is supposed to be in through the side louvres and out under the radiator - the previous owner of Connie had put a small scoop on the side to help push air into the engine bay. Not a bad idea but totally useless when stationary which is when the overheating problems happen.
The main problem is when the van is stationery - especially after a good run. The engine tickover simply doesn't spin the fan quick enough to get rid of the hot air. This is made worse by the exit from the radiator finishing under the engine bay.
I've had to wait several times on petrol station forecourts due to fuel vapour lock
When I put Connie back together I'm going to add a boxed tube to the air exit and take this beyond the back of the van to stop the hot air rising back into the engine bay - I'm also playing around with a ram effect design that will help pull the hot air out when moving forward - not sure if Connie will ever get fast enough to make it work but it won't hurt.
I'm also looking at adding an auxillary electric fan (or fans) to improve airflow around the engine bay.
Finally, I got hold of an Arbath 4 branch exhaust and twin barrel carb so I gain all the space that was previously taken up by the airfilter 'dustbin'. I need to fashion a new tray to fit around the new exhaust - has anyone dones this before?