What are these notches in my Valve guides??—X heads.

[V24x2]

Hello all engine builders, could you please enlighten me on why every valve guide has this machined notch into it? Same place, all 16 guide tops. 1969 X heads. Thankyou in advance!

 

[toolmanmike]

The guides have been knurled. That little notch is for the knurler to start it's travel.

 

[V24x2]

Ahh Thankyou. I did see the knurling down inside, now I know! Thankyou again!

 

[toolmanmike]

That kind of knurler uses a tiny cutter wheel like a glass cutter wheel or like a tubing cutter.