At 16:15 11/06/98 EDT, you wrote:
>
>I'm hoping to accomplish the cylinder head modifications spelled out in the
>competition preparation manual. One of these deals with smoothing out some
>sharp edges in the cylinder head cumbustion chambers and balancing the
>capacities of these chambers to within 2/10 cc. My question is how is this
>capacity measured, with water? I can plug up the spark plug holes with the
>plugs but how about the valves? Does this mean I have to assemble the valves
>and springs each time I want to measure my progress?
>
>Anyone done this? Pass on the experience.
Scott,
I have indeed (on a Dolimite Sprint head). Here is my method, and experience...
I supported the head on 2 wood blocks, positioned so that I could slip the
valves of one chamber into place. I put grease on the valve seats, so the
liquid wouldn't leak. (There is no need to fit the springs and collets to
secure the valves.)
I placed a plexiglas/perspex plate over top of the combustion chamber, again
sealed with grease. (Don't use so much grease that it squeezes into the
chamber, affecting your data.) The plexi plate had a hole in the centre, for
adding the liquid; I had beveled the bottom of the hole, to facilitate
removal of air bubbles; I subtracted the volume of the bevel from all
measurements.
I placed a laboratory burette into a retort stand, positioned it over the
hole in the plexi plate, and carefully drained a precise volume of liquid
into the chamber.
I chose kerosene as the measuring liquid, because, being blue, it was easy
to see. I also thought it would have a lower surface tension than water, so
that bubbles would be less troublesome; I was wrong.
At one point, while trying to manouevre some bubbles out through the hole, I
replaced the head on the wood blocks incorrectly, so that one valve was
pushed open, dislodging the plexi plate in turn, and spilling precisely 34.5
ml of kerosene down the front of my coveralls.
Best of luck, mate!
Allen Nugent
Graduate School of Biomedical Engineering
University of New South Wales
Sydney 2052 Australia
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