Valve Seat Cutters

[Colin Wilks]

Blimey, it's all spend, spend on A7s these days! Mine have been " cut" with a piece of emery paper glued to the underside of my "penny on stick" valves ( 30mm valves with 30 degree seats altered on my Myford 7 lathe but used to be by holding a file on the valve seat zone). Stick valve/ emery disc in guide, attach rubber sucker mounted in electric drill and give it a wizz. Finish off with valve grinding paste and check the sealing with pencil marks on block valve seat. Anyone gringing yet?

I had a single valve seat which was corroded and I thought the time had come for investment in a Neway cutter and pilot. Having discussed things with a very experienced colleague I followed DW's emery paper stuck to valve routine. Result! 

It is amazing how quickly and easily (and cheaply) a decent surface is achieved.

[Jacob Fowkes]

couldn't agree more Dave, looked at the cost of new valves, wept , fired up the lathe.
           

[Bob Culver]

Completely agree with Dave's observation. Ingenious repairs provide much of the satisfaction.
One caution when refacing old valves; presumably the modern replacements are modern materials (non magnetic) which, from experience on other cars, are vastly more resistant to burning than XB and lesser materials of older valves.
3 jaw chucks are not sufficiently concentric and few 4 jaw are free of some wobble.
The stem clarance for Minis etc was inlet .0015 min and exh .002 min. Worth checking before automatically reaming, esp where exh used for inlet. (reamers cut less aggressively if oiled)