Mr. Gasket 8703 Hot Rod Calculator - Manual (Page 52)

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• bore and stroke – you should be able to find this in your en-
gine repair manual.
• Head Gasket bore and Thickness – you should be able to
measure or get Head Gasket Bore and Thickness from the
gasket manufacturer.
• deck Height – you should be able to measure this manually.
• Piston dome Volume – you can measure this, or the piston
manufacturer likely can tell you the valve relief volume. Domed
piston volumes should be entered as a negative number (also,
domed pistons take away from the Chamber volume and as
such, raise compression), whereas dished piston volumes
should be entered as a positive number (they add to the Cham-
ber volume, and have a lowering effect on compression).
• Cylinder Head Combustion Chamber Volume – you will
need to measure this manually.
note: Your Hot Rod Calc User’s Guide does not go into details on
measuring Piston Dome Volume or Combustion Chamber Volume. You
will need to consult an auto repair or engine building resource for that
procedure.
Calculating Compression ratio
For this example, you have a typical Chevrolet 350-CID engine.
your known Bore and Stroke are 4 inches and 3.48 inches,
respectively, and you measured your Combustion Chamber
volume at 76 cubic centimeters. From your gaskets, you find that
your Head Gasket Bore is 4.100 inches and Head Gasket Thick-
ness is 0.038 inches. your Deck Height is 0.015 inches (distance
from top of piston at top dead center to the block deck surface).
your piston manufacturer informed you that your dished valve
reliefs are 4.5 cubic centimeters.
KeysTroKe disPlay
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