Lay the cylinder head on a workbench with two pieces of wood underneath.
Clean all valves from carbon deposits.
Apply coarse carborundum paste to the bevel of the valve seat.
Clamping the valve in the instrument, press the valve disc against the seat, occasionally lifting the valve to redistribute the paste.
Install the valve in the guide sleeve and press the valve disc against the seat.
Measure from saddle seat (dishes) valve springs to the end of the valve stem. If the measured value exceeds the required value, replace the valve seat. For this:
Drill out the valve seat, leaving the seat walls 0.5-1 mm thick.
Press out the valve seat.
Drill out the socket for the installation of a repair size saddle (D+0.3 mm), where D is the diameter of the hole of the old seat.
A - the surface of the new hole;
B - the surface of the old hole.
After heating the cylinder head to 250°C or after cooling the seats, press the seats into the cylinder head.
Adjust the valve seat to the required dimensions.
Saddle sizes (A) - graduation and (B) - inlet valves
Valve Lapping Tool with Collet
General view of the device
Fixture detail
Valve lapping tool, which you can make yourself
General view of the fixture
Fixture detail
When a dull line appears on the valve and seat, wash off the remaining paste and repeat the same procedure with fine carborundum paste.
When a continuous light gray matte ring 1.1-1.4 mm wide appears on the valve and seat, lapping is complete.
A grinding machine can be used to grind the working chamfers of the valves. To do this, it is necessary to install a valve on the grinding machine and fix the movable support so as to obtain the required chamfer angle.
Carefully clean off all traces of abrasive, being especially careful not to get it into the valve guides. Wipe the valves and valve seats with a rag soaked in kerosene, then with a clean rag, and finally, if possible, blow with compressed air.
1 - valve;
2 - grinding wheel;
3 - lever.