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Thoughts on polishing pilots spool valves!

E

Eddie7295

Member
We rebuilt a 870 Rps 34 and polished the pilot spool valves with mothers wheel polish and a soft rag made them float in the bores really smooth, we did it all by hand no power tools at all. What are your guys thoughts on this I have heard horror stories of people grinding the spools would never do that but a good polish makes those things work well.
 
Nope Never do it, they need to keep their Sharp edges to keep them "clean" and working smooth,,, they move in a aluminum bore
cnt
 
CNT is so right, do not mess with the spools they are not the problem, the debris lodged in the valve body is what scores and causes the spools to hang up. As a youngster I use to polish spools thinking I was curing a problem, I only delayed the problem and damaged the spools. Clean the valve bores very carefully as they are soft and can be damaged using abrasive materials. Rod.
 
Cleaning the spool bores is what's needed. The spools are hardened and should only need to be wiped clean.

I know a guy that had a nice old 970 that had the spools stick in his tractor so he took them to a lathe and turned them down .035. needless to say he ruined his tractor within a few hours.

I know you didn't do that to your spools but its an example of the things some people do.
 
When I worked on them I would use an old spool valve and used a engraving tool to slightly rough up the old valve then chuck it in a 3/8 drill and use it to clean and smooth out the bore. Worked great for sticking p.s. valves.

Brian
 
Back in the day (late 70's early 80's I worked in a Case Shop, we purchased a reamer from a tool and die supplier specifically to match the valve body. It to would solve 99% of the sticking or sluggish spools.
I won't say I never used some very fine lapping compound on occasion but I would not recommend it.
 
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