The Stovebolt Site Forums The Shop Area Engine Shop Valve clearance

I don't remember the first year in which new vehicals required unleaded gasoline, but that year and thereafter the engines necessarily required hardened valves and valve seats. Now, when engines manufactured prior to that time are rebuilt, I assume it is common practice to install hardened valves and valve seats to prevent burning.
Valve clearance specifications for those older engines allowed sufficient clearance to prevent burning even with leaded gasoline. The specs for my 1960 235ci calls for .006in for intake, and .018in for exhaust. Even with rebuilt rockers, the exhaust valves are somewhat noisey with the .018 setting. My question is this: has anybody researched/experimented with less clearance for the exhaust?
It would seem that somewhat less clearance could be tolerated now that we have hardened valves and valve seats.
meansam

no "necessarily" about it Sam, our old low compression 235's do fine without hardened seats, tho most [not all] will go that route if the engine is being rebuilt .... valve seat recession has to do with adjusting the valves too tight, way more than the type of gas, and if the 235 valve train doesn't have a nice 'sewing machine sound' they're too tight and you'll have problems regardless of what seats are in it ... go with the designers specs

Bill

meansam, Give em clerance and let em click unless you enjoy doing valve jobs.
Cleon

I'd much rather hear 'em than fix 'em.

Thruwurkin

Remember, Chevrolet stands for;
Can
Hear
Every
Valve
Rattle
On
Lifter
Every
Time

This is most appreciated by those of us who have run a 30-30 Duntov cam Ha Ha
Doug