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Explanation by Jon Jeffords of Hartford WI:

the way it was explained to me,
the Katech whistler is basically an acoustic measuring device that functions much like when you blow air over the top of a beer bottle.

Oversimplified, as the whistler blows air over the the spark plug hole while the piston is at TDC, it measures the resulting natural frequency of the air volume resonating in the combustion chamber. Knowing the air temperature, the Whistler calculates combustion chamber volume at TDC. Knowing the engine's displacement (bore & stroke) and number of cylinders, the Whistler can then calculate compression ratio.

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Also if the engine is fresh, give it some time to fully seat the rings. They say that they seat relatively quick now days but there are a lot of variables here too. Including type of rings used. Give it a little time. If it runs strong don't worry about it.

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How exactly did you perform the compression test?

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Oh OK I see what you are saying. it did not ping but it was just not "right". A person could dribble some water in the carb at a fast idle to loosen up any carbon then take it out for a good blast to expell the carbon which "may" give a false high reading (clean the plugs afterward) and I loosen the plugs on any compression test several turns then tighten em back up then start it & gun the throttle several times to expell potential loose carbon particles coming off of the threads which could lodge under a valve and give a false low reading then pull the plugs & continue on with the compression test. Kinda picky but that's me. Actually I would forget about the SCR/cranking psi for now and button it up with the new intake then concentrate on fixing (in this thread) what ain't "right" on the tune then move on to the fuel needed and the ign curve but your initial sounds healthy and the total ain't outrageous & not sure when it comes in at (springs) but we gotta address/fix the "problem". But you do have iron heads with no quench and those cranking psi numbers are very high & I hear that gas out on the left coast is the worst. But If it ain't pinging then it ain't pinging & that's the bottom line. Stay on it & keep us posted

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The battery was dying, so I actually had to jump it with the battery in my running truck so it had enough juice to do the test. I'm wondering if jumping it off a battery from a running truck may have given false high readings???

I spun each cylinder over for 5 pumps until the gauge quit going up, then took my reading.

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