<VV> "de-tuning" a 110

[Mikeamauro at aol.com]

"...A 110PG combo is just about the most detonation prone combo out  
there... and due to the (relatively) peaky cam, retarding the timing even just a  
few degrees really hits performance, not to mention mileage..."
 
You are entirely correct, Bill. And, in fact, stacking head or base gaskets 
 (as discussed in the start of the string) can actually exasperate the 
110's  propensity to knock and ping. The problem centers around the original 
factory  head design: the relatively high, stock compression ratio (9.25:1), 
coupled with  a relatively large quench space distance (typically .050 or a 
bit more), makes  the 110 prone to detonation. Conversely, a tighter quench 
distance, typically  .040 down to .032, increases turbulence in the combustion 
chamber, and  rapidly pushes the mixture towards the flame front (this is 
good). The  stock quench measurement was not so much of an issue back in the 
day with  98-100 octane fuel, but with today's lower octane fuel, increasing 
the quench  distance (with stacked gaskets, or other means)--while lowering 
the CR simply  makes the engine MORE prone to knock (and reduces fuel 
mileage, too). I  speak from experience. Before my come-to-Jesus understanding of 
quench theory, I  tried stacked gasketing with two 110's: both lost fuel 
mileage, with no  improvement with the knock problem. Since, both engines have 
had their  quench distances reduced to .032, and the compression ratios (as 
verified by  CCing) remains at the stock CR (actually a bit higher: 
9.50:1). Both vehicles  are PG-equipped; and, both are air conditioned. I'm running 
18-degrees BTDC  timing in the 67 coupe, and 14-DTDC timing in the 64 
Greenbrier. I live in (hot)  Florida. Both engines have been in service for 
multiple years, with thousands of  miles driven. I do, however, use 93-octane 
fuel. Latest highway mileage with the  coupe is 28 mpg; the van gets around 19 
(it's a Deluxe, with full seats, fancy  interior and added weight of 
additional sound deadening & carpet). In short:  reduce quench distance; keep the 
stock (or a bit more) compression ratio; don't  go cheap on fuel grade. From 
experience, that's my 2-cents.
 
Mike  Mauro