Topic: Honda OEM Valve Facing

[asphalt900]

Just a Quick Question. Most of the Honda manuals I have make reference to NEVER face the Valves. Some coating I would guess? But on the same page they say to lap the valve, would this not also remove the "coating" around the sealing area? OR is this to maintain the valve margin.  Any HELP!! Thanks, Clay

[70CB750]

I think the difference is in how much you take off, lapping is well within the treated/hardened layer while facing takes more than that.

[asphalt900]

Is the stellite that thick? I normally bead-blast the valves/head before I take them to the machine shop to get seats cut. The blasting turns the valve grey. Is this removing the coating? If I wire-wheel them they maintain the blackish color. Do you think this would be a problem long-term?

[70CB750]

Is the stellite that thick? I normally bead-blast the valves/head before I take them to the machine shop to get seats cut. The blasting turns the valve grey. Is this removing the coating? If I wire-wheel them they maintain the blackish color. Do you think this would be a problem long-term?

Out of my depth here,  but quick search turned this:

http://forums.sohc4.net/index.php?topic=101408.0

Hondaman talks about refacing valves.

[Lostboy Steve]

I wire wheeled the hell out of mine, then had them coated in a thermal barrier coating from Cerakote (just the faces). Then the machine shop cut the valves and seats. It worked out really well so far.

[calj737]

I wire wheeled the hell out of mine, then had them coated in a thermal barrier coating from Cerakote (just the faces). Then the machine shop cut the valves and seats. It worked out really well so far.

Lostboy - CeraKote isn't billed as a thermal barrier, it's a durability and friction reducing layer. Perhaps you meant Cermet as a thermal reflective coating on the valve bottoms, or CeraKote for the stems and faces?

Cermet is also used on the domes of pistons to reflect the combustion heat back towards the combusted portion of the chamber.

I'd think CeraKote would be a proper treatment for the valve faces prior to or post bead blasting to restore the durability and friction properties.

[Lostboy Steve]

Yes it is. The piston coat version is thermal barrier. http://www.cerakotehightemp.com/finishes/C-186Q/piston-coat/

I used the micro-slick on the piston skirts.

[edwardmorris]

Is the stellite that thick? I normally bead-blast the valves/head before I take them to the machine shop to get seats cut. The blasting turns the valve grey. Is this removing the coating? If I wire-wheel them they maintain the blackish color. Do you think this would be a problem long-term?

Out of my depth here,  but quick search turned this:

http://forums.sohc4.net/index.php?topic=101408.0

Hondaman talks about refacing valves.

Some info here

http://forums.sohc4.net/index.php?topic=126735.msg1509838#msg1509838

I had mine refaced per Mark's suggestion as well, came out nice, so no issues getting them done.

[lucky]

You do not machine Honda valves.

You install them, and lap them by HAND only.
Thats it.

The valve seats have 3 different angles.
You recut those on a rebuild... 1.5 turns of the seat cutting tool.