Hardened valve seats - do they really matter?

I have had the exhaust valves done but i had bigger valves fitted at the same time, the shop seemed very keen to relive me of my money and at the time i was not in a position to argue the toss.


if you fit stainless valves, the chances of them micro welding repeatedly to the seats in a cast iron head are greatly reduced

its the micro welding together due to heat in the seat and spring pressure, then pulling away at the surface of the seat as they open that causes the recession.
what is pulled away is burnt off the valve and the process repeats.

like crazy gluing you thumb to your finger. pull em apart and one is the winner and one is the looser when it comes to the top surface of skin....

if you can avoid that microweld due to a good choice of valve material the action of the valve hitting the seat does a very good job of work hardening the the seat anyway further reducing the possibility.

originally the valve head and the valve seat were made of materials that were too alike, and they needed leaded petrol or alternative additives to avoid this microwelding.

id spend my money on new guides, cut for modern seals, narrower stem valves, or headers and a cam.

Dave