Posted by Bulldozer on November 09, 2012 at 19:58:45 from (24.165.92.6):
In Reply to: Re: Valve replacement posted by ASEguy on November 09, 2012 at 15:27:59:
After TOH furnished the stem diameter specs measured al the valve stems with my B&S 1" micrometer. Have the type of valve with constant diameter stems and solid valve guide rather than the mushroom type with the split valve guide. The exhust valves were also non rotators. The valve stems seem to wear more at the top of the valve.
All the valve stems were out of spec. and measured less than the allowable minimum diameter
The intake valves have the most wear.
The valve stems were worn on one side resulting in the valve stem not being round. One orientation measured within spec, Another orientation 90 degrees to the first showed the stem to be under spec diameter. The worst valve was .005" under minimum spec tolerance. The wear spot was noticable with a step worn on the stem
This is the first time, have ever measured valve stems. All my other engine rebuilds were on 2 cycle outboard engines that have reed valves.
Based on the valve stem specs furnished by TOH elected to replace all the valves.
The top of the valves appeared to have sufficent material for resurfacing. However, believe one consideration on re surfacing is the valve cannot seat too deeply, otherwise there will no tappet adjustment. That is the adjusment screw on the tappet could be bottomed out and the valve is not yet seated.
Another thing have experienced is the engine machinist is used to machining three angles on the valve and when you tell him that you want just a 45 degree cut, he looks at you cross eyed.
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