Sealed Engine bay

[Wally]

Hi,
Yeh, it is a good question, but we're not here 24/7 :-)
The pulley side should always be sealed IMO from heat radiating from the header. The valve cover side left and right can/should also be sealed, but that is not really necessary. The flywheel side is usually on purpose not sealed, because cool air can come in more easily that way. The carbs and fan draw a lot of air, so any additional incoming air is welcomed. For the same reason, the area behind the license plate is often cut open. A square smaller than the license plate is used for air intake of the fan. The license plate is mounted a little raised (1 inch or so). Downside of the openings is the cool air that enters from the flywheel side is dirty, not to mention moisty when it is raining...
Hope to have helped you with my views on your question.
Regards,
Walter