Finalising exhaust valves and seats.

I mentioned valve mods before, this old technique used on most properly done heads.

Below you can see a valve, with two lines of blue on the seat.

Simply finish the porting and seat fettling/reduction as shown in the bottom image, then degrease the valve, paint the face in blue, or a marker pen. Lap valve into the seat. You then take the valves down the engineering shop and tell them to back off the backs with a 60deg cut removing the blue area and going right up to the face. This gives another angle between the seat and face and makes a massive difference to off seat flow, torque.
I will round off the sharp edge on both sides of the head too removing the tiny trace of blue on the other side to the main trace and rounding off the head edge.

Angle grinder mounted in a vice (running) and the valve in a drill (running) is the best tool for this work then spin the valve in the drill against some sand paper to finish off.

Here you can see the seat is totally free to flow from microscopic lift without any resistance or shrouding...Basically a 3 angle job, but without the work being done on a machine, the machine used is me with my trusty dremel.

Same deal for the exhausts. Hopefully get the valves down the engineering shop tomorrow £15 for the backing off. Then a skim of the head, then deburring the edge of the chambers where they meet the new skimmed face with some 800 grade wet and dry and we are done. You must just rub a bit of wet and dry on the edge of the chamber after a skim to avoid sharp bits and related detonation issues.