<VV> Lower Shroud removal questions

[James Davis]

Again it is personal preference. Running without lower shrouds and 
airdoors you run the risk of overcooling the engine going down long 
hills.  If you live in FL or TX, that is probably not a 
concern.  Secondly you loose 95% heat and defroster.  Lastly if you 
run through standing water you risk cracking something critical.  In 
my opinion the decrease in cylinder head temps is from the increases 
air flow around the cast iron exhaust manifolds rather than an 
overall better air flow across the cylinder head.  It doesn't matter 
what the reason, the results show a 50 to 70 degree temperature drop 
in cht by completely removing the lower shrouds. I would always leave 
the air door shroud in place and just remove the door assembly (take 
the pivot pin out of the door) as this shroud is used to seal the 
engine and oil cooler.

  Ultra Vaners typically run with out the air doors but with the 
lower shrouds in place for engine heat and so the exhaust manifolds 
can be reversed (side to side & end to end).  This allows the system 
to operate like the 1960 car system but without temperature 
regulation.  Moving the exhaust and mufflers away form the valve 
covers results in a 20 degree drop in oil temperature as well as a 
cooler running engine.

Personally I would never run any Corvair engine in anything but a 
track car without the lower shrouds.   The air doors are another 
subject and that depends on the particular application.
Jim Davis
.



  At 02:58 PM 7/1/2007, David George wrote:
>Quick question about removing lower shrouds. I have read a lot of 
>threads where folks say then run for the summer without lower 
>shrouds to improve cooling of the heads.  Since the linkage to the 
>bellows doors is connected to those shrouds, are they also removing 
>the doors for the summer or letting them flop free after removing 
>the linkage with the shroud? Thought I'd ask since I will be 
>removing the shrouds on top and bottom to do a clean out. Thought I 
>might just leave the bottoms off for the summer if it won't hurt 
>anything. Thanks!
>
>Dave