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| − | *1. Piston deck height. This is the dimension from the crown of the piston to the flat deck of the block with the piston at top dead center. *Nominally, with a premium 350 piston and a virgin, uncut block, this dimension will be about 0.025".
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| − | *2. Squish. This is the dimension from the crown of the piston to the underside of the cylinder head with the piston at top dead center and *adding in the thickness of the compressed head gasket. Current thinking is that a squish of 0.035" to 0.045" works best.
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| − | *3. Compression height. This is the dimension from the centerline of the piston's wrist pin to the top of the piston's crown. With a premium *piston in a 350 Chevy, this dimension is about 1.560". Lesser quality rebuilder pistons will measure out at around 1.540". This will *increase the piston deck height and the squish and make the motor more sensitive to detonation.
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| − | *4. Stack. This is the combined dimension of the crankshaft radius, rod length and piston compression height. A common stack with a 350 Chevy *would be about 9.003". That would be with a crank radius (half the stroke length of 3.480") of 1.74", rod length of 5.703" and piston *compression height of 1.560".
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| − | *5. Block deck height. Nominally, this dimension would be about 9.025" on a virgin small block Chevy cylinder block. So, when using a stack *of parts equalling 9.003", this would result in a piston deck height of about 0.022". Combined with a steel shim head gasket thickness of *about 0.018", this would result in a squish dimension of about 0.040", just in the middle of the desired range of 0.035" to 0.045" to help *prevent detonation with a reasonable (nominally, about 10.0:1) static compression ratio on pump gas. Alternately, a builder might cut the *block decks down to the height of the stack and use a more conventional composition gasket that specs out at around 0.040" compressed *thickness. If you had a stack of 9.003", cut the block decks down to 9.003" and used a 0.040" gasket, then the piston deck height would be *0.000" and the squish would be 0.040".
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