<VV> CHT Re: valve seats and "Ping"

[jvhroberts at aol.com]

 Too hot. If the heads were cooler, there wouldn't be so much pinging. Gages don't fix this problem, we all know it's there. Better cooling does! 

Sure, Viton and synthetic oil survive this kind of heat a lot better, but it doesn't change how hot the combustion chambers are operating. 

 

John Roberts
 

 

-----Original Message-----
From: FrankCB <FrankCB at aol.com>
To: patiomatt <patiomatt at aol.com>; jvhroberts <jvhroberts at aol.com>; virtualvairs <virtualvairs at corvair.org>
Sent: Sun, May 13, 2012 2:16 pm
Subject: CHT Re: <VV> valve seats and "Ping"


Matt and John,
     Some decades ago when I drove my 1965 180 regularly to work, it would NORMALLY run at 400 deg.F (stock gauge and thermistor) on level highways at 55 to 70 mph.  Occasionally I would "floor it" going up a long hill to see what boost I got and the stock CHT would go to 450 deg.F. but I did have a electronic knock eliminator (Carter EKE) which may have saved me.  The boost reached 8 psig on a non stock gauge.  It was only after I insulated the exhaust piping UPSTREAM of the turbo that I was able to get 10 psig.  But the stock exhaust piping lasted only about 6 months before it disintegrated at the UP-bend due to overheating of the metal (according to the chief metallurgist at the chemical plant where I worked).
     My other Corvairs (110 and 95 hp models) I ran with an aftermarket CHT gauge installed.  This was a Stewart Warner "Corvair Cylinder Head Temperature Gauge" (Model 366-LW) with a gauge that ran from an indicated 200 to 500 deg.F. and included a thermistor that was installed in the STOCK 3/8 in. tapped hole in the "forward portion of the left cylinder head".  I checked the calibration of the gauge in boiling water and it was right on using 14 volts.  In operation both the 110 and 95 hp engines normally indicated 350 deg. F.  Except for the two times when I let it get up to 450.  One time I had to drive home on only 3 cylinders due to only one functioning carb fortunately on the left bank.  The other time I had to drive home local roads with NO functioning fan due to harmonic balancer separation.  Both times when the temp got over 450, I stopped for a time and let the engine cool off before resuming my trip.  Both times the engine suffered no apparent damage, but it did have the advantage of synthetic engine oil and Viton O-rings.
     That's why I believe EVERY Corvair needs at least ONE CHT gauge.
Frank "likes gauges" Burkhard
Boonton, NJ
 

In a message dated 5/10/2012 4:08:22 P.M. Eastern Daylight Time, patiomatt at aol.com writes:



OK, after some reflection, that may be a bit too   conservative. I do know, once 
CHT reaches 400F or more, detonation and   preignition become a LOT more prevalent 
here. And no doubt, all that   knocking will beat on things in a way that not only 
kills power, but   engine parts as well, and seats come to mind...

John   Roberts

=========================================================


    My exact  beliefs!  When in SoCal I did everything possible to keep   from pinging...keep the heads near 300F.


No that I'm on the Oregon   coast I find I can run the 400f for efficiency....  and not   rattle!


I've only lost 3 seats in my life.


Matt   Nall
Charleston,   Oregon
http://tinyurl.com/The-Patio
http://tinyurl.com/Matts-Tech-Pages











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