Richard/All:

Well "magic" is not a good answer for me but there is a pretty good answer from Speed-O-Motive at:

http://www.speedomotive.com/Building%20Tips.htm

Apparently for squish between 0.035" and 0.060" the gas is squeezed sideways to create TURBULENCE that reduces detonation. In addition, if the piston comes close to the underside of the slightly cooler head, some cooling of the piston occurs, again reducing detonation. Also no benefit seems to show up if the squish is more than 0.080" but 0.060" might be needed to allow for rod stretching at high rpm (>6000). This answers my question that 0.025" deck + 0.015" gasket = 0.040" squish would work and be a little safer than 0.035". In addition I have learned from Richard that he thinks any cam with more than 200 degrees duration at 0.050" lift will degrade mpg. Thus my search for the ultimate cam now looks like GM part No. 3896929, the original 300 HP cam for the SBC 327. The duration of this cam at 0.050" is listed as 195/202 with lifts of 0.390/0.410 I/X. This cam fits Richard's formula for mileage and if I can get 300 HP with this cam in a 350, that is enough for me just cruising and telling myself I am getting 300 HP, although I think I will add an Edelbrock Performer intake and ceramic-coated short tubular headers. Well Richard is the expert with a little help from Speed-O-Motive and I have learned a lot. What a Forum!!!!!

Best Wishes,
Don Shillady
Retired Scientist/teenage rodder