How smooth should the O.D. of a relief valve be?

[hobbybob517]

Mine is like this

is the O.D. important?

Haven't got a mic this small.
Meassuring with my calipers it is 15.9 mm.

Thanx.
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[anthracitedub]

Smooth enough so it fits in the bore without sticking. I just polished one with a piece of 600 grit pAper. I took a thread tap that would hold it and chucked it in a drill motor... then some light oil with the 600 paper, just enough to smooth it over.

You want the face of it to be true and clean and most importantly, the seat in which it contacts inside the bore.

[hobbybob517]

Thanx,

I will lap the face to the seat with some valve grinding paste.
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[mark tucker]

a little with 600 then 800 or 1000. I dont know if doing to the face helps or not..probably not. be sure there are no sharp edges.

[hobbybob517]

Thanx Mark,

I'll get some 1000 grit tomorrow.
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[modok]

Don't put grinding paste in the block please, it's too easy to get it stuck in the soft metal. you'll likely lap the tool more than the work.
Cut mag with HHS.

Piston OD should be 15.93-15.98mm

[hobbybob517]

Thanx Modok,

I guess i won't lap it then.

I will take it into work today and mic it.
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[modok]

I've made kind a reamer/endmill kind of thing to go in there and square the end of the bore, and I know a lot of other guys have done the same,....but it's not terribly important to do that. Helps keep the idle oil pressure up slightly, but getting the oil pump play down, and making sure the OD of those plungers are not excessively small is more important. They "seal" on the sides mainly anyway, if you look at how the passages are layed out.

[Slow 1200]

[nsracing]

Don't lap it in the case!

I would not use anything abrasive. If there are any burrs, just run a very fine file. Using a file to machine and smooth things out is a skill everyone needs to develop. Old craftsmen have used files to finish metal back in the day. And it is still relevant today.

[mark tucker]

I have a reamer shortened recut for end cutting with a sleve aliginement bushing on it for reserfacing the case.I had a moron bring me a 2387 mag case that has the oil gally or the relief hole relocated from the factory so the hole wasent centered witch is fine.but the tool the factory used wasent right for the job and chattered all to hell.so i mad a tool to fix it. other than that ive not seen one that needed reserfacing.I think tomany people think thats a major issue.witch if it's chattered like that one was it may be.but not normaly. better to have a correct size piston that fits right and is smooth. how did it get rough??shit going through the oil. the same moron brought me another newly blown up motor of his(also had less that 1000 miles on it like the first one) and the pistons in it looked as if they had been shot with rat shot from a shot gun.on the top and sides...that motor came from the north west.Im not permited to say the builders name on the samba. he's the winy typ and everett gets enough shit as it is with out a scaming moron crying to him. .
so I wouldent bother reserfacing it if it were me unless it was realy effed up

[hobbybob517]

I mic-ed the o.d and it's 15.95mm

not sure if i want to file it down, i guess i'll just 1000 grit the high spots off

it asn't stuck in the bore or anything,
just wanted to check if it was ok while i have it out.

Thanx for the tips guys, i appreciate it.
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[nsracing]

I did NOT say file it down!

Just run a file lightly on the surface -not digging into it. Any burr that sticks up will get caught in the file.

It is kind of like filing on a lathe. You just lay the file lightly by its weight. The idea is to just barely kiss it.

Better yet, just leave it alone.