<VV> Valve rotators

[BobHelt at aol.com]

In a message dated 8/31/2006 3:44:50 PM US Mountain Standard Time,  
dmonasterio at megared.net.mx writes:

I payed  attention to the exhaust valve rotators. When I rebuilt this engine, 
years  ago, I installed those valve rotators just because I had them at hand 
and had  been readed that were used on FC engines but, have never known why. I 
just  know that they rotate the exhaust valves and it is good on FCs but have 
no  idea on real differences or advantages depending on engine usage. I have 
not  enough light on my old brain to understand why valve rotators on FCs and 
not  cars. It should be a technical reason but, can't find it. 
Do  somebody in the group have a better brain lantern than mine ?

Thanks in advance for any light

Daniel  Monasterio



Hi Daniel,
I hope that I can can shed some light here. First, as I remember, the valve  
rotators were only used on the 1961-62 FCs. The rotators were to assure that 
the  valves rotated in operation so as to rub the contact surfaces and 
eliminate the  possibility of carbon particles adhering to these surfaces and causing 
a burned  area or a pitting. This was thought to be necessary due to the 
loading and  "work" aspect that the FCs would be subjected to.
 
About the same time, the design of exh valves on all of the other Corvair  
engines was changed from a single groove keeper to a four bead keeper. This new  
design allowed the exh valve to be free to rotate. So when the valve was 
opened,  the coil of the valve spring imparted a rotation to the valve. This 
accomplished  the same rotation without the rotators. So this new design eliminated 
the need  for rotators per se which were heavy and limited the engine speeds.
The 140 hp engines never used this 4 bead design for some reason.
 
Regards,
Bob Helt