[FC] bottom shrouds and damper doors

[James Davis]

It all depends on what engine and what distributor.  I run a 166 cuin. 
140 engine with a Ray Sedman AP 272 cam and his high squish, fast burn 
heads with headers in my 61 Rampside.  The distributor is a modified 140 
manual with 34 degrees total advance @ 2,500.  I leave lower shrouds and 
air doors with thermostats on year around.  Even at 70 mph on a 105 
degree F day the cylinder head never gets above 350 F (Spider dash with 
cylinder head gauge calibrated at 350 degrees).  Yes it has A/C, a 
gasoline heater and a Safeguard.  The engine needs 91 octane or better 
gasoline when the temps are above 85 degrees.  If below 85 degrees, 87 
octane will work fine.   It take a gear drive starter to turn the engine 
over as the compression ratio is 10.5:1.  The cold cranking cylinder 
pressure is 175 psi.   I have about 110,000 miles on the 11 year old engine.
Jim Davis

On 1/1/2012 2:43 PM, Mikeamauro at aol.com wrote:
> "...In regards of the lower shrouds...In the summer time here in the
> Tucson desert, I believe with the shrouds and damper doors , t-stats off my eng
> runs cooler... In the cooler months, I put the shrouds  back on in order to
> have heat in the cabin. Some say the eng was engineered to run year around
> with  shrouds and dampers on, to regulate and have even temps of the eng and
> the oil  temp. . Was the corvair, and especially the vans ever tested in
> the  extreme  desert heat,,,? ...So what is the general  opinion out there?
> Leave them on or take them off?...Ron J Bloom..."
>
>
> My 2-cents: here in Florida, with both my Corvairs, I seasonally  remove
> and reinstall the lower shrouds. If I do not, during summer months, even  with
> the heads modified with a .032 quench distance, running 93-octane  premium
> fuel, and using SafeGuards, knock and ping can be an issue (for power  and
> efficiency, I typically run 14-degrees initial advance in the van, and
> 17-degrees with the 67 coupe... both have 110s). I must add: both vehicles are
> air conditioned , and have PG transmissions. The crux of the issue, back when
>   our vehicles were engineered, the available fuel was much higher octane;
> hence, then, Corvairs would likely run OK, in all seasons, with the lower
> shrouds in place. A hot engine is not necessarily totally bad, until the
> temperatures reached cause detonation.
>
> Mike Mauro