KB 96 (2056) fly cut valve notch, 8 notches: 4 intake and 4 exhaust ...Pics and instruction Options

[rfinegan]

After the engine fail on my 2056 the investigation began measuring the piston the valve clearance. I tried the clay/ Playdoe method and the results were not as good as I would like. So i set up the failed Number 1 piston with the smiley (IMG:style_emoticons/default/smile.gif)


I set up the head from the other side without the bent valve and used the rocker shaft spring (just a light weight spring I had handy)to push down the valve till contact was made with the piston and the cam lobe was starting open the intake. At about 10 degrees on the degree wheel the closest reading was 0.080. ( this was in the small indentation made by the valve failure)

I tilted the mill head to align with the valve guide and set the piston in the v blocks and used my 123 blocks to center the piston pin.


I indexed the center of the intake valve with a pencil to set the Y axis on my Bridgeport.


Centered on the mark, I now had to find the correct x axis. Since I already had the mark from the valve on the piston, I set the fly cutter .100 more than the diameter of the 44mm valve. The marked put the piston top was indexed and moved my X axis in to touch the previous valve mark. I then moved my X axis .050 inch and confirmed my zero to the cutter.

I moved my Knee (set to zero) .050 inch to make the first cut. The piston crown of the KB measured at .220 ( for a min .170 thickness). This feels like a safe depth and puts my clearance at .130.

I will repeat the process on the 2 valves notches with no "kiss' marks by marking up the piston tops with marker and using the valves to get the reference mark by hand

[rfinegan]

@maf914

Thank you for the encouragement. There will be a Dyno day in my future! I hope it will be before the new year.

As for the sharp edges and preignition and hot spots, you are correct. Same with the stress risers on sharp milled edges. They need to be radiuses too. I was referencing this a little as I used grinding/sanding and not a Cutter to make my notches. It is what had/could make . But it does make for softer edges. A bit harder to make things repeatable for volume depth and weight. But EZ to take a few 0.10 of a gram out for final balancing.

For those wondering how to get the depth correct on an angle quill? MATH?

I do not know either.

No DRO (digital read out) here. So I got out my feeler gages. Or more correctly Wire Spark plug gages. I selected the 0.50 wire gage and lay it flat along the milled pocket at the deepest. I guest a straight edge razor blade across the piston top to feel for it to catch. I continued to cut till the razor no longer catches on the gage. Then some sanding sticks to clean up and radius.