We all know how datsuns love to rust out the water box's and the front upper long member due to funky design and inability to coat inside and then rust when they get blocked..

Question is, besides a little water from the windscreen wiper holes, what purpose does the cowls have besides looks? Normal cars have the air intake for the heater box in the waterbox/plenum area under the cowl but on the datto is doesnt...

Reason I ask is that im busy doing the loverly task of refurb the body and as with just about every 1200 i get a nice stream of water on my feet when it rains, I have sealed it and repaired it nice but was actualy thinking of making a sealing plate under the cowls so it looks like they are still there but no water can get in besides a few drops from the windscreen wiper holes which can just run out as per OE design..

Opinions plz.

Cowl Top Grille vents purpose is to prevent debris from entering the air intakes for the passenget compartment air flow. Things like leaves and twigs.

Many cars in days past had a similar air flow system. Most after the 1970s do not, the have a unitized heater/airflow system.

But the 1200 doesnt have any entry from the waterbox into the cabin/hvac... this is why I ask

Sure it does. It's not a "waterbox", it's more like an airbox with an air/water separator and a drain. The simple baffles you can see under the Top Grilles are the air/water separators.

1200 tech - Ventilation

I just cut a piece of tin as a tempLate then cut inside the line by 5 mm and they fit under the cowl nicely. I painted it black. Have noticed no water comeing in now hehe

Never mind, im totaly blind, i see its right up in the middle between the center,