I have read that valve lapping compound, as it is abrasive, should by no means get into valve guides as it will impede the reciprocal motion or damage the valve. Should I worry about small amount residue amounts that are left over in the valve shaft and can be seen through intake runners but difficult to reach? Should I try to clean it with an air pistol or water blast?

1 Answer 1


If you are hand lapping the valves you should have the springs, retainers, etc removed. You can remove the valve and clean the valve stems and guides. I would use a parts cleaning solvent on the valves. Use a nylon or plastic brush on the guides. A steel brush may scratch the inside of the guides.

  • of course, they were all off when i was lapping
    – amphibient
    Commented Jul 31, 2015 at 16:23
  • are you saying remove the valve after lapping to clean it out and then put it back in for final reassembly ?
    – amphibient
    Commented Jul 31, 2015 at 16:29
  • Yes , you want the valves and guides clean and lightly oiled. Beside the abrasive residue getting into the vale guide you could also draw it into the combustion chamber and deposit it on the rings or cylinder wall.
    – mikes
    Commented Jul 31, 2015 at 16:32
  • OK. i didn't do it that way exactly. i oiled the stem before lapping, put it in, lap and then put the spring back in and load it.
    – amphibient
    Commented Jul 31, 2015 at 16:33
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    @amphibient - Follow mikes advice: disassemble and clean everything. You will be sorry if you don't as you will destroy the heads (well, at least the valves, seats, and guides). Take the time and do it right. Reaching in with something to clean areas will not get things as clean as they need to be. Remember what I said: Cleanliness is next to Godliness. If you do it right, you won't have to worry about it. Commented Jul 31, 2015 at 19:51

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