<VV> Early to late 110 head changes

[BobHelt at aol.com]

In a message dated 1/6/2009 6:45:11 PM US Mountain Standard Time,  
bryan at skiblack.com writes:

I had an  interesting conversation about milling some heads.  In the   
past, I've had late model heads milled about .050" to .060" to  remove  
the gasket step and create a quench area that reduces  knock.  All  
those heads were '65 and up.  Yesterday I was  told about a set of '64  
110 heads that would require about .100"  milled to remove the gasket  
step.  I always thought that the  deck height on the closed chamber  
heads were the same.  Anyone  else heard of this?

--Bryan



Why yes, in fact.
 
Please see below, 
 
 
Chevrolet, in its conservative fashion, designed the squish gap to be  0.050" 
for the 1960 Corvair engines.  But then, for reasons unknown, increased the 
gap to 0.107" for the 1961-64 non-  turbo engines. This of course lowered the 
detonation resistance but was never  known to be a problem. 
During the mid-1960s, as the muscle car market emerged, Chevrolet was  
anxious to gain every possible horsepower from their engines and did so on the  1965 
Corvair engines too. 
So, for 1965 and following thru 1967, they reduced the squish gap down to  
0.054" for all non-turbo and non-AIR  engines. This made a quarter-point 
increase in the compression ratio (1964 to  1967) that boosted the net horsepower. 
(Advertised horsepower remained the  same.) 
Regards, 
Bob  Helt
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