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Lycoming exhaust valve reamer size ?

Larry DeCamp

Well Known Member
I need to ream a sticky exhaust valve on my 0320 w/Superior cylinders. Lycoming / Superior suggests to ream .4995 and mcfarlane sys .5005. Any experince to share on this ?
 
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Brush Research FLEX-HONE Cylinder Hone, BC Series, Silicon Carbide Abrasive, 1/2" (12.7 mm) Diameter, 240 Grit Size
 
Thanks moosepileit

I assume the carbide brush is meant to remove deposits ? I am advised that sometimes the guide and stem simply gall each other fabricated to proper tolerance. If this is the case, I may need some metal removal on the guide. I need to tear it apart to define the objective. Thanks much.
 
Reamer size

I have a IO-360 180 hp and I bougtht an adjustable reamer.
This way you can work your way to the final size 0.4995.
But I'm sure it will work just fine with a standard
0,4995 reamer.
It worked well.
 
I assume the carbide brush is meant to remove deposits ? I am advised that sometimes the guide and stem simply gall each other fabricated to proper tolerance. If this is the case, I may need some metal removal on the guide. I need to tear it apart to define the objective. Thanks much.

No galling there. The valve stem is polished steel and the guide is something softer (usually bronze, but Lyc may have gone to something different) and is reamed to size. The are not fitted with the intent that they will wear into clearance. Wearing in this application is the enemy. Steel running in bronze is a time proven method with no galling.

Brush hones, when used properly, do well at removing deposits and lightly scoring (grit determines the depth of the scoring) the guide without any material removal and therefore clearance increase. You DO NOT want material removal in this effort. Scoring is mildly beneficial here as the valleys help to hold oil, just as they do in your cylinder walls.

Larry
 
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I've always thought a reamer is the wrong tool for this particular job....never had any subsequent guide issues once cleaned up with a ball hone. Its also a heck of a lot easier to set up and get done.
 
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