milling cylinder head sealing surface

[pzi993]

I took the heads and cylinders off while changing the cylinder o-rings - oil leak. The pistons and head domes were covered with carbon deposits so I cleaned them off with the wire brush on the drill. I ran into the cylinder sealing surface with the brush a few times and that surface does not look fresh. Should I mill that head surface before putting new head gaskets in? If so what is the going rate for this service? Here is how it looks:

[prschmn]

I have found 3.6 heads are nearly always warped to some degree so a small skim is in order.
Adds $20 per to do a set.

[onevoice]

A quick way to check is to put some fine valve lapping compound on the sealing surface and mate it with the appropriate cylinder. A little back and forth movement by hand will polish the surface enough to see how good the sealing area is.

[pzi993]

Originally Posted by prschmn

I have found 3.6 heads are nearly always warped to some degree so a small skim is in order.
Adds $20 per to do a set.

This is what my subie expert tells me. I have a kind of appointment with Ridge Reamer next week

[pzi993]

Originally Posted by onevoice

A quick way to check is to put some fine valve lapping compound on the sealing surface and mate it with the appropriate cylinder. A little back and forth movement by hand will polish the surface enough to see how good the sealing area is.

This can actually work since the head and cylinder have that mounting guides that allow for both to be spun around. I need to lap my valves anyway so getting a valve lapping compound will give it a try but just as a proof of concept before I get the surface milled.

[prschmn]

Keep in mind that lapping compound is meant for steel on steel use. I'm all for you trying it
but would suggest something a bit less agressive.
Most of the heads I see aren't out all that much .002-.004 but plan on drinking a few beers by the time you're done!

[pzi993]

... the fridge is in the garage :-)

[Nine9six]

Originally Posted by prschmn

Keep in mind that lapping compound is meant for steel on steel use. I'm all for you trying it
but would suggest something a bit less agressive.
Most of the heads I see aren't out all that much .002-.004 but plan on drinking a few beers by the time you're done!

Not exactly true...^^^

...and like sandpaper, lapping compounds comes in various grits, so agressiveness is dependent upon grit and medium.

Timesaver Lapping Compound Yellow Label and Green Label Compounds, non imbedding lapping compound, manufactured by Micro Surface

[mikedsilva]

Can you post a pic of the corresponding cylinder tops? Curious to see what mating surface you have... do you have gaskets?

[pzi993]

Yes - new porsche gaskets and cylinder o-rings are on their way. Here is are the matching head, cylinder and used gasket. Zoom on cylinder matching surface - I guess they both need to be milled next week.

[pzi993]

I guess my Ridge Reamer shop did not work out - they are too busy and I need to look for alternatives. Any recommendations on a machine shop in Denver to mill the surfaces?