<VV> Subject: I want Compression!

[Mikeamauro at aol.com]

Seth has covered, very well, methods to increase compression ratio.  Whatever 
method used, don't forget to address the  quench distance: as "born," in 
engines I've examined prior to  rebuild, stock Corvair quench distances exceeded 
.050. With today's pump  gas (even 93 octane premium), anything more than .040 
does little to  attenuate detonation. I'm presently running two 110s, quite 
successfully,  with .032 quench distances. As both are on air conditioned, 
powerglide  vehicles, I choose to stay near stock compression ratio (.25 over at  
9.5:1). Prior to adjusting the quench distance, neither vehicle, no  matter how 
much I fussed with the timing, would operate in warm  weather without knock. 
Adjusting the quench space can be accomplished in  two ways: cut out the step 
in the cylinder head (then take out material in the  head and from the top of 
forged pistons (opposite the quench area) to get back  to the desired chamber 
volume); or, weld in new material into the head in the  quench area and 
machine to desired height (as I recall, this also required  adding and resurfacing 
the gasket surface, a bit, too)... then remove  material away from the quench 
area to get back to the desired C.C.  volume. Both engines have been together 
and running for several years, now,  and the details are a little fuzzy, but 
the welded up heads would be my choice  if/when done again. As Seth mentioned, 
no matter what, check and correct valve  train geometry. I've also noticed, 
even though the available roller rockers  are supposed to be the correct ratio to 
replace stock rockers, geometry  changes a bit when using roller rockers. You 
might also seriously consider  employing a Safeguard knock control system.
 
Mike  Mauro          

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