Mr. Gasket 8703 Hot Rod Calculator - Manual (Page 54)

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Calculating Mill amount
Another method of increasing the Compression Ratio on your
engine is to mill, or remove material from, the heads. Generally,
you will have a target Compression Ratio you want to achieve
and you want to determine how much material to remove from
your engine’s heads.
note: Your Hot Rod Calc User’s Guide does not go into details on the
milling process. Your local engine building shop will likely have the nec-
essary knowledge and tools for milling your heads to your specs.
For this example, you want to increase your Compression Ratio
from 8.5:1 (current Compression Ratio) to 10.5:1. your Stroke
is 3.48 inches. The following keystrokes will show you how to
calculate the amount to mill.
KeysTroKe disPlay

0.
1. Enter your Stroke and current Compression Ratio:

sTroK 3.48
in

CoMP
raTio
8.5
2. Enter your target Compression Ratio and calculate the Mill
Amount:
 *
(Mill Amount)
Mill 0.098
in
**
* Repeated presses of  will toggle through the inputs and outputs,
starting with the entered Stroke.
** To raise your compression from 8.5:1 to 10.5:1, your engine building
shop would need to remove 0.098 inches of material from the surface of
your heads, thus reducing the overall Chamber Volume and increasing
compression.
Notice the answer to your mill amount question is given in inches,
0.098 inches, but it’s a simple press of a key to convert to millimeters, if
necessary. If you press the
 key, your calculated mill amount of 0.098
inches is converted to about 2.48 millimeters.
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