Re: Is this valve job OK?

[Simon Favre <simon@domain.elided>]

I would say this valve job is *NOT* OK. What may be going on is that the
valve seats are OK, but the valves themselves are not. Even a brand new
valve should be "dressed" on a valve grinding machine before installation.
This ensures that the sealing surface is perfectly circular and concentric
with the stem. If you hand lap it, you may mess up the multi-angle grind
on the seats, depending on how far off the valves are. Have the valves
dressed, then repeat the "leak" test. You can also use solvent poured in
the chambers (with old spark plugs installed). They should not leak. If,
after the valves have been "dressed", you still get some leakage, hand lap
the valves, but not too much. If you have to lap them a lot, the valve job
is no good. One non-destructive test you can do easily is to coat the
valve sealing sorface with Prussian Blue, or even a Magic Marker, and 
gently rotate the valve against the seat. Where the metal is in contact,
the color will be gone. Where there is no contact, the color will still be
there. If you show this to the shop that did the valves, they may take the
whole thing back and re-do it. 

Before you do anything, I would suggest that the shop should be offered
the chance to make it right. If you go and grind on all the valves, THEN
claim they screwed it up, they may disagree. Just tell them the head
failed a leak test.

Kevin Charles Trent wrote:

>I need advice on a rebuilt 2000 cylinder head that was delivered to me.
>The head was done on an exchange basis, and as I was working on it (with
>the combustion chambers facing up under bright lights), noticed that I
>could see "daylight" through the valve ports.  The cams were not installed.
>  To investigate further, I layed a 24" shop light over the combustion
>chambers then covered it with a towel.  As I looked up both intake and
>exhaust ports, I could literally see very thin rings of light around every
>one of the valves at the sealing surface with the valve seat!!  Some valves
>more than others, but light through all 8 valves nonetheless.  This would
>not pass the factory seal test!
>
>I checked two other (used) heads and could not duplicate this condition.
>This reconditioned head has new valves and valve seats, and was supposed to
>have a "multi-angle valve job".   Everything is very clean.

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