valve lapping question
valve lapping question im lapping my valves and ive got one intake valve that wont seal. ive lapped it 4 times. first 2 times i did it with my thumb, that didnt seem to cut it. poured gas in the intake port, still leaking out. so i tried it twice with a drill. i didnt run the drill very long only a several turns in each direction on low speed. i put gas in it and its still seeping out.
i could put the drill back on it and just turn the **** out of it but i dont want to go too far. am i just not cutting it enough? the valve is straight far as i can tell.
i could put the drill back on it and just turn the **** out of it but i dont want to go too far. am i just not cutting it enough? the valve is straight far as i can tell.
A competent machine shop should be able to cut a VJ for you, but you may want to be more selective if want a good performance VJ.
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If the rest are fine, you would only need to have one seat touched and the valve faced.
Are you blueing the valve and seat prior to lapping?
A blue felt pen works fine. Just paint the seat and valve face with it, then very lightly lap the valve to the seat with fine compound. . You should be able to see what the issue is.
If the blueing is gone all around the valve face, the seat is the issue. If not, the valve is the issue, likely slightly bent.
Ron
Are you blueing the valve and seat prior to lapping?
A blue felt pen works fine. Just paint the seat and valve face with it, then very lightly lap the valve to the seat with fine compound. . You should be able to see what the issue is.
If the blueing is gone all around the valve face, the seat is the issue. If not, the valve is the issue, likely slightly bent.
Ron
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Joined: Aug 2006
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From: North Bay, CA
We go $350 for the valve job which includes a radius cut on the exhaust seat, and 5 angle intake seat. Surfacing is $120, seals are ~ $20. $500 if it includes a little bit of SSR and bowl work would be a good deal.
Don't try to correct a seat that does not seal with lapping, it will never fix the issue of concentricity or seat erosion which is the root cause. Lapping should only sparingly be used to check seat width position on the valve, it should not be used to try to correct for bad machine work or wear. Get a valve job done.
Joined: Aug 2007
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From: Turnin' Wrenches Infractions: 005
Is it cutting a circumference around the valve evenly? You should be able to see a thinner area indicating there is a problem. The grinded area will look fresh, and areas where they aren't touching will look different.
