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]

set up
pic

[Jamie]

set up
pic

The arc of the fly cut is a curve, but notice the ding in the old piston is flat across the base, like the face of the valve. I'm no machinist, but you need to cut a flat across the fly arc to give safe relief. (IMG:style_emoticons/default/aktion035.gif)

[PatMc]

set up
pic

The arc of the fly cut is a curve, but notice the ding in the old piston is flat across the base, like the face of the valve. I'm no machinist, but you need to cut a flat across the fly arc to give safe relief. (IMG:style_emoticons/default/aktion035.gif)

Without knowing the shape or relief in the cutting tool, it's tough to figure out what we're looking at. The cutting tool needs to effectively be a chunk of HSS with a radius slightly greater than the fillet radius on the valve. I think what we're seeing on the inside radius of that arc is where the brazed carbide stops, or it's not aligned with the tool shank...and it needs to be for this operation to work. I would personally just use a 1 7/8" endmill for this....but mostly since I happen to have one in the drawer. lol.