REFLECTOR:Mag Timing Slipped?

Mon, 09 Feb 2004 08:55:23 -0600

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It's a puzzlement sure enough.
<... Is it reasonable to think that the points could wear enough
to cause the timing to move that much ...>
The points don't wear measurably, but the rubbing block does.
Rubbing block wear causes point gap to decrease, dwell to
increase, timing to retard, so that wouldn't seem to be the
problem.
Interesting phenomenon ... Be sure and let us know when you
track it down ... Jim S.

Ronnie Brown wrote:

> I am doing my first condition inspection on my 173 Elite RG
> and all is looking great except: When I checked my Slick mag
> timing, I found it at 32 degrees BTDC.  Since our Cessna 172
> in 10 years never had the timing reset except for the 500 hour
> mandatory inspections of the Bendix dual mag, this has me
> scratching my head.  The timing on the Jeff Rose has not
> changed. The retaining bolts were tight, an internal
> inspection of the mag reveals nothing (however, I have not
> checked the internal timing yet) , and I KNOW the timing was
> set correctly (25 degrees BTDC) on this Lycoming IO360.  I had
> a low static RPM - 2100 rpms - so we checked everything before
> changing the prop.  Any worn parts in the gearing would cause
> the timing to be more retarded. Is it reasonable to think that
> the points could wear enough to cause the timing to move that
> much? Or any other ideas? THANKSRonnie Brown

--
Jim Sower ... Destiny's Plaything
Crossville, TN; Chapter 5
Long-EZ N83RT, Velocity N4095T

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It's a puzzlement sure enough.
 &lt;... Is it reasonable to think that the points could wear enough
to cause the timing to move that much ...>
 The points don't wear measurably, but the rubbing block does.&nbsp;
Rubbing block wear causes point gap to decrease, dwell to increase, timing
to retard, so that wouldn't seem to be the problem.
 Interesting phenomenon ... Be sure and let us know when you track it
down ... Jim S.
Ronnie Brown wrote:
<blockquote TYPE=CITE><style></style>
I am doing my first
condition inspection on my 173 Elite RG and all is looking great except:&nbsp;When
I checked my Slick mag timing, I found it at 32 degrees BTDC.&nbsp; Since
our Cessna 172 in 10 years never had the timing reset except for the 500
hour mandatory inspections of the Bendix dual mag, this has me scratching
my head.&nbsp; The timing on the Jeff Rose has not changed.&nbsp;The
retaining bolts were tight, an internal inspection of the mag reveals nothing
(however, I have not checked the internal timing yet) , and I KNOW the
timing was set correctly (25 degrees BTDC) on this Lycoming IO360.&nbsp;
I had a low static RPM - 2100 rpms - so we checked everything before changing
the prop.&nbsp; Any worn parts in the gearing would cause the timing to
be more retarded.&nbsp;Is it reasonable to think that
the points could wear enough to cause the timing to move that much?&nbsp;Or
any other ideas?&nbsp;THANKSRonnie
Brown</blockquote>

--
 Jim Sower ... Destiny's Plaything
 Crossville, TN; Chapter 5
 Long-EZ N83RT, Velocity N4095T
 &nbsp;
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