Joe---Normal readings for your engine (1974)? should be close to 125psi.
If you got appreciably less than this, take out all of the sparkplugs,
tie back the throttle, and do another compression test.
I've never taken this test with the throttle plates closed, so I can't
say what the difference might be. Logic says the air has to get into
the tested cylinder from somewhere, but it may be able to slip in past
other open sparkplugs and valves while cranking with the throttles
closed.
Let us know!
Dick.
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