How come we never do valve jobs anymore?

In the old days valve jobs were common. You never hear anyone say they had to have one anymore.

How come we never do valve jobs anymore?
Gasoline had the lead removed which required a different grade of material to be used on valves and seats, so they last longer. There are also systems cleaners that will remove many deposits from the valves.


However some of us still do a valve job at 80 to 90 thousand miles because there has been a loss of performance.
Reply:Both the answers are partially correct. The biggest reason is modern engines have less valve dammage is due to much better fuel management fuel injectors that spray just the right amount of fuel for conditions. This also accounts for longer engine life pistons and rings wear less. But wait! now many engines have oil change intervals at 7,500 miles so we trade valve jobs for engine sludge. Or low speed driving intake valve deposits.
Reply:Fuel injection has all but erased the carbon build up on valves.


When engines ran with a carburetor, the carbon build up was pretty bad.
Reply:Most of the currant answers are correct, this just ads to them.


In my day, valve seats were part of the head and materials were softer thus wear caused irregularities which had to be corrected. Burning valves due to high wear and temperatures.


When they started installing steel valve seats (pressed in) they pretty much solved the problems. Also the heads have better cooling circuits now, than they had back then.......


45 years engine mechanic, all sizes...........
Reply:improved metallurgy,multiple smaller valves,cleaner fuel