I learned that warped (uneven) cylinder head surface that goes against the engine block can be remedied by taking to a machine shop to get it resurfaced, basically to make it flush all the way so that it sits tight against the gasket in between.

But what I was curious about is, if they shave a couple thousands of an inch from the cylinder head height, can that cause the valves to not close all the way because they are designed to be closed at the factory setting? If the heads height is less, the equally sized valve will have a leak in the otherwise closed position in the amount that they shaved off when resurfacing. Or is that insignificant and withing an allowable margin of error?

1 Answer 1


The valves sit recessed inside the combustion chamber. When you machine the head, the combustion chamber becomes smaller (has less of a depression), but this does not do anything to the valves or valve seats where the valve resides. Look at this image and you can see what I mean:

enter image description here

This is an image of n dual overhead cam (DOHC) head. At the bottom, you can see the flat area. This is what gets machined. The valves are a good distance (in machining terms) away from the head surface and don't get touched during the process.

  • oh, so the valves are entirely inside the cylinder head.
    – amphibient
    Jun 17, 2015 at 18:35
  • hey, any idea how much i would look to pay for machining of one cylinder head of a Tacoma V6 engine (so 3 cylinders, if it makes any difference) ? Location Mid Atlantic
    – amphibient
    Jun 17, 2015 at 18:39
  • You'd just have to track that down yourself at your locality. There is no way I could suss that out plus any information could soon be outdated. Not really the place to say. Ask over at The Pitstop ... I will over there later after work. Jun 17, 2015 at 18:50
  • The Pitstop ? Where would that be ?
    – amphibient
    Jun 17, 2015 at 19:05
  • @amphibient - The Pitstop. Jun 17, 2015 at 20:36

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