A long uphill grade where you can run wide open throttle in high gear for a mile or more and a stopwatch makes a pretty good field expedient "dyno". Make several runs at various RPM starting points, and make ONE change at a time such as ignition timing or fuel metering, etc. Compare times and you'll be able to get a good comparison between runs. On the race engine dyno runs we did we would also try to have similar ambient temperature, atmospheric pressure, and relative humidity conditions if at all possible.
Jerry
