G'day folks,
As Mystyler has said, the 'Easy Spin Starting' decompression system used on these older Briggs, means that compression test gauges are of no real use as a diagnostic tool.
The excerpt which follows is taken from the 1981 edition of B&S' 'Service And Repair Instructions'.
The intake lobe on the camshaft is ground with a small ramp which holds the intake valve open 1/100 of an inch for a tiny fraction of the compression stroke. At slow starting speed the interval of time that the valve is open is relatively long and therefore enough air escapes to noticeably reduce the compression. However, at operating speeds the interval of time is so short that there is practically no escape and therefore horsepower is unimpaired. Actually at 3600rpm the valve is opened for a mere 1/200 of a second. In all other respects the valves operate as in any other four stroke cycle engine.
The force required to start an engine is reduced by 50% with 'Easy Spin' and would be noticed most by a person who has difficulty starting the ordinary engine.
The test that the Briggs manual recommends, is to spin the flywheel in reverse to normal rotation, and see if it 'bounces back' when it approaches TDC.
BTW, ODK has a good range of Briggs Repair Manuals for download at
https://www.outdoorking-forum.com.au/forum/u...stratton-workshop-manuals.html#Post20019This one, filename 'Briggs & Stratton Service and Repair Instructions 1984.pdf' is actually better than the later CE8069-1 version, I find, for the older engines.
