TS Vave seat grinding and piston pins

[SunbeamS7]

I need to cut valve seats in my TS and i note that modern engines/valves typically use 3 different degree cutters. Just wondering if someone would be kind enough to clarify if such is needed on my TS, or i can  just use the singular 45 degree cutter?
I'm using new valves via LDMCC.

Additionally, I am also installing new J&P pistons and i note various opinions on the forum regarding using "buttons" to retain piston pin vs circlips. I had wondered if the buttons were preferred as they allow piston pin to move/get oil and seemingly the circlips don"t?
I had wondered about ensuring that the piston pin does have some side to side play in it and then use the circlip retainers.

Thoughts appreciated,
Regards
bryan

[graeme]

Hi Bryan

Buttons are used to prevent the danger of circlips popping out of the pistons, and wrecking the cylinder bore. The gudgeon pins on the 2 3/4hp are such a small diameter, that the little circlips don't have much spring tension.
Buttons made from tufnol seem to be a popular choice.

Cheers, Graeme

[douglas1947]

Hi Bryan,

you use the 45° (modern cutters are sometoimes 46°) if the seat bfor the valve is worn  / burnt.
The other cutters, 60° inside and 15° outside are used to correct the valve seat to the valve dia.

Michael

[SunbeamS7]

Thanks for getting back to me and clarifying the use of buttons/valve seat cutters, greatly appreciated. Its always good to know the "why" behind something !
Regards
bryan