skullandbones

I have never worked on aluminum heads so this is a slow process to transfer what I know over to a different medium. I changed from a 1/4 inch shank, air driven tool to a 1/8 inch shank rotary tool with very precise speed control. I found right of the bat that the aluminum is much more critical as far as "touch" to get the same results. A very slight pressure on the material with grinding stone gets the same results as from significant pressure with a carbide cutter on steel. So I'm beginning with the exhaust runners as they have less work to accomplish a smooth surface. The exhaust ports have been raised in the casting which will flow better. The only real work with a stone was around the guide boss which I will still clean up on the final hand work. The other "defect" as I see it was a ring around the whole runner about a half inch in from the valve seat. It was removed on the long radius from about 4 to 8 o'clock but I wanted it gone all the way around. I will reduce turbulence but probably not add to flow rate. The other work was around the base of the valve seat interfacing the machined surface. It looked a lot worse than it really was by feel. The surface smoothed out nicely with a sanding drum. The runners are supposed to be 70 cc so I'm not concerned about making them too big but that won't be an issue since I took out so little material. These look at least twice the size of my GT40 heads. After smoothing out the guide bosses a bit more it will be ready to do final hand smoothing of the walls by sanding with 400 grit transversely across the runner. It will produce a smooth surface that still has enough texture to create a boundary layer to create a non turbulent flow. I've got a few shots of the "as cast" runners and then work as I progressed. It's good this is a loose schedule build since it would severely tax my patience if I had to keep my nose to the grindstone (ha - ha!).

Thanks,

WEK. :cool::cool: