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Date: Fri, 18 May 2007 00:13:23 -0500
From: David Staten <Dastaten@earthlink.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Cold Crank compression check
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During some of Chris's "cranking" sessions, we decided to conduct a 
compression check for grins and giggles.

Max compression was impressive, with 80-90 PSI noted. BUT. It was only 
one chamber that did this on each rotor.

Rear Rotor had 80, 65,65 or so
Front had like 85,70,60 or so.

This is within book spec for differences, and this engine was assembled 
over 18 mos ago (but kept oiled internally). Has never been run since 
rebuild by us. To my knowledge, every rotor and seal was mic'd within 
spec, and we were meticulous with assembly. We have made a point to coat 
the inside of the intake or exhaust ports with MM or WD40 and manually 
turn the engine by flywheel or prop. ALWAYS good sounding compression. 
ALWAYS oil mist from the ports. All the apex seals are compressible. 
visual inspection reveals no issues.

Did anyone else ever do a cold compression check prior to first start? 
Should I not worry about these numbers unless they persist after we've 
started the engine and blown/burned out the pickling?

Dave