>The two engine tins that fit directly under each cylinder head are
>missing on my '77 Camper (the omnibus). Would it be worth scrounging
>around for replacements, how much of a cooling effect is the engine 
missing?

Yes, it would be. These pieces direct the cooling air out of the engine to
the rear-- the same direction the air is flowing under the bus as you drive.
This creates a slight venturi effect, helping to draw the cooling ait out
from the cooling fins in the cyls and heads. The lack of these tin pieces,
_might_ create a slight high-pressure zone where the cooling air comes out
as the under-bus air collides with various exposed engine parts. If so,
this could slightly inhibit cooling.

In addition... air isn't the only thing that can collide with your engine
parts. Lots of pushrod-tube oil leaks, come fom rocks etc. bouncing off
your pushrod tubes.

 -Steve Maher      smaher@gi.com   '71 VW Transporter w/bottom
                                  engine tin and no pushrod tube leaks :)