I've got a B18B head with KMS ultimate valve train package and I'm wondering if I should lap the valves. I'm concerened about doing this because the KMS valves have a coating. So If I lap the valves I'm worried about it taking the coating off and doing more harm than good.

Of course I could check and see if the vavles even need lapping but in the even they arent seating correctly what do you all recommend??

 

I would imagine you would need to lap them at a bare minimum. What role does the coating serve in the area where the valve sits in the seat? Heat transfer?

 

The nitride coating is supposed to make the surface harder, adding to the surface harding already. I would imagine the surface (micro crystals) wouldnt do much good anyway after a 1000 mile period if the nitride coating comes off anyway....

 

If you dont lap the valves in then they WILL NOT seal properly. I did it when I installed my S2 valves. Same thing as the ones you have.

 

If the valve grind was done properly you should not need to lap them and should not have sealing problems. Nitiriding is a treatment to the metal, not a coating per say although in the case of a valve I would imagine its only a few thousandths thick.

 

I will check if the valves need to be lapped, and if in the even they do need to be I will do so...

Thank you all for your time and help

 

just have the valve seats re-cut and slap the valves in make sure the seat cutting is top notch then you don't have to worry about grinding the coating off your valves

 

I read that the abrasives in the lapping compound will reduce seat life, that's why they are cut rather than ground in most performance applications.

 

cut them and check margins thats the way to do it

 

engine rebuilding shops has a vaccume pump with a big rubber nipple that connects to the intake/exhaust port to check for leakage, install a set in one cylinder and let them check if its sealing like it should, before cutting\lapping them.

 

wow really? lapping your valves takes two minutes, i would never install a set of valves without lapping them. If your coating comes off that easy, its junk!