wolfebrian13

"Any one with an idea or ballpark specification for seat contact width for both Inlet and Exhaust Valves?"

I have recently undertaken the task of rebuilding the motor in my 2001 Honda Civic EX 2D Coupe. NOTE: Purchased used 4 weeks ago with 184,XXX miles.
This rebuild came about due to a misfire in cylinder #4 caused by an oil soaked combustion chamber and spark plug.

Going through the list of causes for excess oil in the combustion chamber i thought it better to just rebuild the motor from the ground up considering i was going to have to pull the head to diagnose the cause anyways.
Once I had the head off, with no sign of oil leakage past the head gasket, i noticed that the rear most exhaust valve in cylinder #4 was actually broken (Burned?). Among other issues like seized oil rings and worn compression rings (Max PSI 180, actually in cylinder #4. 1, 2 & 3 all at 170psi), completely clogged EGR port, stuck PCV valve and not one gasket below the crank shaft.

Due to the broken and severely carbon caked valves, i have decided to replace them.
I am in the process of lapping them into the seats, however have had very little luck locating a seat contact width spec.

Any one with an idea or ballpark specification for seat contact width for both Inlet and Exhaust Valves?

I have attached a couple pictures just in case your curious.

Slumpertcivic

Start the lap with the fine compound, spin it 20 times and the. Wipe it down and see where your at. I had 1mm worth of seat surface that was available to grind down to before the edges, I took off about .25 of that in grinding out most of the pits.

I didn’t bother trying to get every last pit out as I knew I made a huge difference over what it was and frankly it was running fine enough besides all the oil issues like you had.

All that oil likely has played havoc on your catalytic converter.