Hardened Valve Seats or Not?

No Model T ever had hardened seats. The last Model Ts were rolling off the assembly line right when tetraethyl lead was being introduced in gasoline, so all they had was unleaded fuel and they lasted a long time. I know a gentleman in fact with an original Model T in this county still running and the engine has never been into. He drives it a pretty good bit.

The main cause for valve seat recession is running with no or a dirty air filter. Dirt particles find their way into the engine and get between the valve and seat. Grinds seats to pieces.

Another less popular cause is when stellate faced valves are inadvertently put into heads with non hardened seats. Those valves are much harder than the seats and will ruin them in short order. The valves and seats must be of a similar material in order to last like they should.

Also, if the application is to be heavy duty such as a truck, hardened seats were installed. I have a 1956 331 Hemi on the stand and it came from the factory with hardened seat inserts installed because it was in a 56 Dodge D500 dump truck. Chrysler knew the rigors those motors were going to go through.

Extra resistance on an engine such as heavy vehicle weight or pulling loads makes exhaust temps go up. This is easily proven looking at an exhaust temp gauge on a diesel truck. Stand on the gas and watch the exhaust temp go up.

In applications like ours, light A bodies, hardened seats are just not necessary. Hot rods generally run cooler because their owners don't want them running hot. So they routinely have extra capacity radiators, high flow water pumps and thermostats and high performance fans to help keep temperatures down. This also has a drastic effect on exhaust temps.

Plus, you will always have the grim possibility of a seat working loose and letting go. With no seat insert, that is not a possibility.

Keep your air cleaner element changed regularly, keep your temps down and you will never have a problem with running non hardened seats.

It's just another stupid passed down myth just like the 3000 mile oil change.

Believe what you want. That's the truth.