engine valves machining

[vizard]

Hi all, I'm a newbie here so please excuse if I'm kinda slow. Ok, my question is this....I've a set of stainless steel valves which has a bigger valve face than my existing valves in my engine. So I'd like to know if it's ok for me to machine down the face without any problems? Would it still retain the required properties without premature failure?

[NatFJ55]

I thought valves needed grinding, like on a lathe with a toll post grinder.

[Boots]

Valves and valve seats have to ground to the same angle. If not then air and gas can leak by and you will not get the preasure required.

[vizard]

Yes I realise that, even new out box valves need to be ground to match valve seats on individual cylinders. What I wanna know is if there's any problem if I were to machine down those bigger valves to the the same dimensions as the new out of the box valves before sending them to the engine shop to get them to do the grinding. Would the newly machined surface lose any of the properties and would I need to do any treatment on it?

[vizard]

anyone have any idea or can help me out with this?

[mactec54]

Hi vizard

You can machine any part of the valve you want I have made hundreds over the years
& by just machining the OD of the head & making a new face/seat not a problem the only valves that can be a little tricky sometimes are sodium filled but you are not doing these

If your machining is good you don't even have to grind them just lap them in for a perfect seat/seal

When machining the valve hold the valve stem in a collet if you have one & surport the head of the valve with your tailstock with a live centre & a round piece of bar pushed against the head of the valve you don/t need much pressure just touching is enough to stop any vibration when cutting you only need the support if the valves have a large dia head above 1.00

[vizard]

mactec54, thanks for your reply and thanks for the info you've been great help.