'A' head seat #10 (exhaust) showing surface cracking across mating face. The pink tinge is the residue from the die penetrant fluids used to test all of the seats and highlight these problems. The pencil marks on the casting point roughly to the cracks in the seat. Also of note are the concentric ridges on the seating face. This shot is after grinding, yet these rings persist. As this is the only seat so marked I can only conclude that an earlier visitor had tried to 'step' this seat to overcome the known fault.
Seat #11 (exhaust) is the only other seat displaying any signs of cracking.
|A close-up of the cracked seat. It can be seen that the main crack extends down the vertical face for about 1/8". After much consultation, it would appear that the only sensible method of removing these screw-in seats is to mill away the body to the thread core and then pick out the thread material (a job for the specialists!). Assuming that the correct seats can be acquired, re-insertion is a relatively simple task. New valves and guides will also be fitted - assuming that they can be sourced.|