Lengthy Response to Re: <VV> Corsa update - compression and temperature

[FrankCB at aol.com]

Guus,
    My comments are interspersed in your original  email.
 
In a message dated 6/24/2006 4:06:33 PM Eastern Standard Time,  
corvair at corvair.nl writes:
 
[SNIP]
[Took it for  
a drive but it ran hot again very soon. Even at low  speeds like 40/50  
mph it runs at 400F. Contrary to a "normal"   water cooled car with  
heat problems the temperature goes quickly down  again if you just  
leave it idling. My guess is it could idle all day  and never run hot.  
It's definitely connected to higher  revs.]



Guus,
    It's not the higher revs, but the higher engine  LOAD or greater power 
production required for higher speeds that generates more  heat.  But IMHO, 400 
deg.F is NOT excessively hot for a Corvair  engine.  When I was running my 
1965 180 Corsa regularly driving to work  every day, it normally reached 400 
deg.F. just cruising at highway speeds (60 to  70 mph).  When under full boost (8 
to 10 psig) the CHT would climb to 450  deg.F.  This was on the stock 
UNcalibrated gauge, so the numbers may not  be quite accurate.  However, I also ran a 
1966 95hp Monza for many  years that had a CALIBRATED aftermarket Stewart 
Warner CHT gauge  installed.  (I calibrated it myself in a silicone oil bath using 
a lab  thermometer).  This calibrated gauge normally read 350 deg.F. although 
we  did manage to get it up to 480 deg. F driving home from an autocross on 
only 3  cylinders and another time driving a few miles home without a 
functioning fan  (slipped harmonic balancer).  This engine had Viton O rings so it 
managed  to survive these high temps.
    Anyway, I don't think 400 deg.F is excessive for a  Corvair engine.  And 
remember that the higher the engine temp. the better  the gas mileage since 
less heat is "thrown away" (discarded) into the cooling  airstream.  Anybody for 
ceramic Corvair engines??? 
 
[SNIP]

[Option 2
Distributor trouble
Like I mentioned before  the distributor is the only (main) part  
that's not rebuild. I've timed  it at 20-24 degrees at 850 rpm like  
the manual suggested. How can I  check if the centrifugal and pressure  
retard are working correct? I  looked at the manual and at 2000 rpm  
the pressure retard should retard  the time. If it doesn't and the  
timing stays at 20-24 degrees would  that make an engine run hot?]
 
Guus,
    The stock 180 engine has a FIXED timing advance  from idle to 4000 rpm 
UNLESS boost is developed.  This is why the turbo  engine is "doggy" (sluggish 
response) and the fuel mileage is so poor compared  to the NA (normally 
aspirated or UNboosted) engines.  (See my chapter on  Turbocharging in the Corvair 
Basics manual for details on how to improve  this)
    Retarding the timing tends to make the  engine run HOTTER.  Before Jim 
"inherited" my 140 purple  Corsavertible, I used to retard the timing 
considerably to increase the  combustion temp and thereby reduce the hydrocarbon level 
in the exhaust in order  to get the engine to pass the yearly New Jersey 
emission  test.  Together with leaning out the carbs this got the  car passed for 
another year but the car drove like it had about 40  hp.  A half hour later when 
the car was back in the company parking lot (it  was lunchtime) I would 
REtune the engine back to it's normal stock settings  and it ran great for the next 
364.8 days (until time for the next  inspection(:-).  

[SNIP]
[There's only one big BUT concerning this retard thing.  There's an  
Safeguard retard unit on this car. This unit can  electronically  
retard the timing if detonation (pining) occurs. The  display however  
shows very little action of the unit. At least it  doesn't act in the  
range the car is already running hot. Only when I  really boost it the  
Safeguard takes over every now and then. Nice unit  btw.

The Air/Fuel ratio indicator on the Safeguard also give an  almost  
perfect ratio (13-14) while driving. Only running a little lean  on  
acceleration but quickly becoming normal again. That's why I rule  out  
fuel problems.

First I could adjust the valves again. But  then I would like to know  
how I can detect one or more collapsed  lifters. With the distributor  
probably the best option would be to  ship it to Dale Mgt for a  
rebuild but I would like to be sure if  that's really necessary and if  
it's really the reason the engine runs  hot.

What else could cause it? Opinions welcomed.

Sorry for the  long post. The good news is that tonight I took it for  
a nice drive  through the woods nearby. As long as you keep the revs  
down you would  never know it has a problem ;-)

Regards,

Guus de Haan
The  Netherlands
'65 Corsa Turbo-Charged Cvt]



Guus,
    With the good results from your compression tests,  I wouldn't worry 
about your valves and their actuation since they are not  causing your engine 
temp.  If you still think your temps are too high (I  don't), investigate your 
cooling system for possible blockages by taking off the  top shroud with the fan 
and even clean out some of the flashing that may still  be present between the 
cooling fins.  Also make sure that both thermostat  doors are FULLY open at 
highway speeds.  Since they may close partly at  idle, you need someone to 
follow you on the highway close enough to see that the  thermostat doors are fully 
open (horizontal position).  Also make sure that  the air recirculation 
opening located below the oil cooler is blocked off to  keep hot air from 
recirculating back to the engine compartment.  If this  cover is missing, make a new 
one out of thin sheet aluminum or other lightweight  metal.
    Hope we see you at the Buffalo CORSA  Convention.
    Regards,
    Frank "