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Originally Posted by lust4speed
The stock engines I've torn down have all been .005" to .008" in the hole, and I haven't come across deeper ones. Maybe just luck of the draw.
The couple tech papers that I've read indicate that there is a no-man's zone between .050" and .080" that is very prone to detonation, and staying below or above the zone is necessary. This would explain why hemispherical heads are fine. The math also says that with a standard .039" thick head gasket then the piston should be no more than .011" down in the hole before additional risk of detonation occurs. Something gets nasty with flame travel in that zone that doesn't happen with less or more clearance.
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With factory head gaskets at .045, seems they'd be detonation prone as built.
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Will Rivera
'69 Firebird, 400/461, 290 Eddy D-Ports, HR 230/236, 4l80E, 8.5 Rear, 3.55 gears
'69 LeMans Vert, XS 350, #47 heads, TH400, 10 Bolt 3.23 gears, work in progress
‘66 Lemans, 455, 310 KRE D-Ports, HR 236/245, TH400, GV OD, 12 bolt 3.73 gears - see it here:
https://youtu.be/RP_s1wJKm_Y?si=K0NZxoTyaGcj8Dcb
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