Thread: enlarging the intake valve reliefs

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Isky has tools to rent, but they have always been out of them whenever I tried to use them.
http://www.iskycams.com/onlinecatalog.html
If this link does not show the tool, go to page 17 Isky catalog, valve notching tool.

I have made my own cutters in the past from an old valve and a lathe tool bit. Sharpen the edge of the bit and silver solder/braze it to the valve face. Use a bushing collar with a set screw on the valve stem to limit the depth of cut. Grind the end of the bit for a 0.125" radius to prevent a sharp corner on the piston crown.

McMaster Carr has the collars and tool bits. Go to their site and type in Shaft Collars for the collar. Type in Square Tool Bit Blanks for the bit. 1/4" x 2 1/2" M2 high-speed steel is what you'll need.

Like this....

If the intake and exhaust valves are very different diameters, you may want to make two tools. The flat part of the cutting tool needs to be at least 0.050" longer from the centerline of the valve to the tip of the cutting tool so that when you make your cut, the valve relief will be at least 0.100" bigger in diameter than the valve head you will use in the motor.

Valves dance around in the valve guide bores more than you might think and you need to allow this clearance in the valve reliefs.