Spent this afternoon working on the heads. I picked up a long carbide burr during the week so I would be able to re-profile the valve guide bosses. My electric grinder runs at 25,000 rpm which is way too fast for a 6″ long burr, so I also bought a speed control kit from Jaycar Electronics. Once I built the kit I plugged in the grinder to see how well it worked….perfect. Even at slow speeds the motor runs smoothly.
You can see below that the valve guide bosses are pretty chunky. The plan is to not remove too much material, but slim them down so the flow is maximized.
The pics below show the work 95% complete. All that is left to do is put a small radii at the bottom corner of the valve bosses.
Last job was to polish the combustion chambers a little.
I’m done for the day, and my thumbs are numb from 6 or 7 hours of grinding!