Why do valves keep needing adjustment

I know why they need adjustment, but what is wearing out to make the need for the adjustment in the first place.

Thanks, Kev

the consistant smashing of the valve into the valve seat and the seat into the head

One of two things happen
The seat gets slowly smashed into the head so it is moving closer to the rocker - hence the gap between where the valve comes to rest iis less
The valve is slowly stretching

If your valves constantly need adjusting (they are always tight) then your head is wearing out

Thanks for the reply and this is along the lines I was thinking. But if you need to adjust them every 1500kms or so (as I'm told), I would think the head would be stuffed in a year or two.

Ta, Kev

you need to check every 3000 miles (5,000 kms)

If you have to adjust to often your head is on the way out

Mine havent moved in quite a while

Oh, thats not to bad then if its only 'check' every 5000k's, and obviously adjust if required.

Thanks Bizarre.

P.S. My car isn't even on the road yet, but was curious for the future 👍

I believe its mainly because of the HIGH temperatures attained and sustained for long periods of time...

the steel and alloys all expand and contract at different temperatures etc...

back in the old days - 1950s & 1960s

If the tappets weren't adjusted every oil change the Worst thing that could happen [and did happen]
the Dreaded Dropped valve - or Head of the Valve -

I haven't heard of this happening lately...
although I tell everyone to have them done every oil change..
Maybe the Valves are better quality than back then...

OR - it was because of the oil cooler heating up the air on Number Three cylinder because the oil cooler used to sit
there...

the ends of the valves do get mushroomed though
and this is with standard valve springs...
[and standard valves]

cheers

Lee