omega0684
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| posted on 14/4/09 at 07:12 PM |
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reconditioning valves & valve seats
how do you go about reconditioning valves and their seats as i have managed to get a few of them out without using a spring compressor. the exhaust
valves are obviously the worst, it was very difficult to get the hard carbon of the back of the valve the inlet valves are not that bad.
how do i get the sealing faces nice and clean? will i need to re-seat the valve seats etc?
any advice welcome, tricks of the trade etc
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prawnabie
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| posted on 14/4/09 at 07:26 PM |
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mount a drill in the vice and put the valve in the chuck. use emery cloth to clean the carbon off but don't go up the stem.
If the faces aren't badly pitted then just lap them back in.
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omega0684
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| posted on 14/4/09 at 07:28 PM |
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how do you tell whether they are badly pitted?
y don't i clear the crap off the stem?
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prawnabie
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| posted on 14/4/09 at 07:34 PM |
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I was told that you can damage the stem quite easily with abrasives! dunno how true it is like!
Just clean the crud off and see if they will lap in, you are looking to make a dull grey line on both the faces (valve and head) without any gaps in
the line - gaps are pits in the surface!
Shaun
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D Beddows
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| posted on 14/4/09 at 08:03 PM |
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To be honest a wire brush in a bench grinder is better (plus a pair of sturdy gloves and a certain delicateness of touch  ) you almost always mark
the valve stem if you tighten a chuck round it - even with tape wrapped around the valve. I would clean the stem as well and I tend to find a very
gentle polish afterwards with autosol shows up how worn the valve is a treat. The parts of the stem that don't go anywhere near the guides will
come up mirror finish and the rest should be a little duller in a used but ok valve - in a really worn valve the difference will stand out a mile!
Then you lap the valves in with grinding paste to get a good (or should I say better) seal - if after a couple of minutes with coarse grinding paste
you haven't got a continuous line around the valve and seat then you may have a problem but to be honest the seats or valves have to be pretty
knackered for it not to happen. In my experience though to start to notice any real difference once you've put everything back together (unless
it was REALY nasty) you need new valves, guides, properly cut seats and a bit of porting..........
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snapper
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| posted on 14/4/09 at 09:11 PM |
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The thought is that if carbon has built up on the stem, it effectively seals the guide, if you remove the build up you can get excessive stem to guide
clearance.
Another of those jobs that can end up with an expensive head rebuild if not carefull
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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D Beddows
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| posted on 14/4/09 at 09:31 PM |
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It is one of those jobs that you should either do properly or not bother doing at all really 
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sickbag
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| posted on 15/4/09 at 07:21 AM |
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If the valve seats have regressed so far into the head that you didn't need a spring compressor to remove the valves then you may as well get
the head reconditioned by a professional company - or get a decent head.
Finally back on the job!
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g.gilo
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| posted on 15/4/09 at 08:33 AM |
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spring comp
one here if u need it.
graham
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mcerd1
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| posted on 15/4/09 at 09:20 AM |
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Alex, got any photo's ?
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