Knowing the volume of your combustion chambers and ports is important for several reasons.
The most important reason is because all your ports and chambers should be the same volume. Another
reason is because in most cases, you want to keep the volumes as small as possible. By using the
simple techniques illustrated here, you will be able to keep your port and chamber volumes in check.
When measuring engine part volumes, the CC, or Cubic Centimeter, is the standard unit of measurement used.
How much is a CC? The large blob of water is 1cc, or One Cubic Centimeter.
The smaller blob of water is .2cc.
To measure and dispense CCs of water, I like to use this Universal Pump Dispenser, by Hyde Tools, at most paint or
hardware stores (Item #30460) for about $5.00.
To measure chamber volumes, you will need a small piece of 1/4" plexiglass, about 4.5" X 4.5", with
a small hole (about 1/8") about 3/4" from the edge. Your local glass shop
should be able to cut you a piece for a small fee. My local glass shop offered this piece to me for free,
if I agreed to leave peacefully.
The Dispenser Pump needs to be graduated, so I made up this scale
with MSPaint. Download the BMP file, print it from your Windows Paint program,
cut it out as shown and tape it to the pump.
To measure the combustion chamber volume, apply a small bead of white
grease around the chamber. Also, apply grease to the valve seating surfaces and set valves into position.
Either install a spark plug, with oil or grease on the threads, or as I prefer,
plug the spark plug hole with Plumbers Putty, from any hardware store.
Press the plexiglass onto the chamber deck with the hole at the edge of the chamber. You want to
tilt the head so that the hole is at the highest point. This will help prevent
bubbles from getting trapped around the edges of the chamber as you fill it with water. You can see voids in the grease if it is not
sealing the plexiglass to the deck. Now carefully fill the pump with water by sucking it up from a glass, do the Markus Welby thing
where you squirt out bubbles as you set the plunger for 12 or 10CCs, and inject the water into the chamber
through the small hole. Easy does it, if you inject the water too fast, you will create bubbles. Keep track of how much you
inject into the chamber.
To measure intake port volumes, I just install a valve, with grease on the seating surface
and stem, level the flange surface and fill to the brim. Not using a plexiglass
cover is less acurate, but port volumes are not nearly as critical as chamber
Same with the exhaust port, except remember to plug any thermactor holes
with plumber putty, and don't even try to measure an exhaust port that has a cross
over or intake manifold heating port in it.
While measuring port volumes, I hold the valves in place by using old valve stem seals with springs,
held in tension with retainer keepers.
To download the Pump Scale BMP file, right click
and select "Save Target As". After downloading the file, open the file, Cc1.bmp, using MS Paint and print it
from the Paint program. The scale should measure 2" from the 0cc mark to the 10.2cc mark. The scale may not
be accurate enough to satisfy the Dept of Weights and Measures, but is probably
fine for most shade tree porters. The scale has a .2cc resolution, but
because of the resolution of MS Paint, the first .2cc mark on each CC mark is
a little short.
Using water will create flash rust on your iron parts. Pros use alcohol, but I always use water.
The proper way to measure CCs is to use a burret. They offer much more accuracy, but they are hard to
find and not as easy to setup and use.
Bubbles are always a problem. You can add a drop of detergent to your water to help
reduce bubbles caused by surface tension, but you must be very careful not to create foam
bubbles by injecting water too fast.
Be careful when removing bubbles and setting the plunger on the pump that you do not squirt your eyes or
someone elses eyes (and no running with the pump in your hands!).