Harden Valve Seats---1927 Engine

[BLB27]

Is there a consensus that harden valve seats should be installed when rebuilding a T engine?

[Erik Barrett]

Only if the original seats are worn or damaged beyond use. The unleaded fuel thing is nonsense because these cars were built before leaded gas came out. Modern fuel and lubricants are far superior to what they were designed to run on. If your seats are in good condition your money bid better spent on other things.

[Dan McEachern]

What Eric said. Even then, hard seats are not required- cast iron seats will be just fine.

[J and M Machine]

I disagree: The reason being is that if you are going to drive the vehicle on a regular basis then you should install them.
The other factor to take into consideration is the new valve is harder against the stock cast iron block surface and will pound the stock seat out.
If you're going to rebuild the engine and make it for the long haul then install the seats.

If you're going to drive it in a one mile parade once a year you can go without.

[Dan McEachern]

It's ok- we can disagree on that!

[Kerry]

I've only ever replaced seats when required, have rebuilt many engines with over size valves out of later brands of engines and cutting new seats in the cast and many now having high mileage on them, no valve problems, not even ever having to re-set lash.

[Kevin Pharis]

I do agree that the hard seats are a more reliable seat material... but are overkill for the valve temperatures seen by a relatively low output engine equipped with quality stainless steel exhaust valves. The real cause of valve seat recession is carbon steel exhaust valves operating near their fusion welding temperature. The higher operating temperature stainless steel valves will prevent the microscopic fusion welding that causes valve seat recession.

I install seats when necessary, but feel that installing seats every time is a “belt and suspenders” approach to reliability. No doubt that a T engine with all hard seats will outlive us all...

[J and M Machine]

I do agree that the hard seats are a more reliable seat material... but are overkill for the valve temperatures seen by a relatively low output engine equipped with quality stainless steel exhaust valves. The real cause of valve seat recession is carbon steel exhaust valves operating near their fusion welding temperature. The higher operating temperature stainless steel valves will prevent the microscopic fusion welding that causes valve seat recession.

I install seats when necessary, but feel that installing seats every time is a “belt and suspenders” approach to reliability. No doubt that a T engine with all hard seats will outlive us all...

Yes Your last sentence says it all for us. Since we have the block in the machine it only costs a few dollars more to do all, to go one step more knowing that the engine will outlast us and into the next generation. That's what it's all about and that's why we do it.

[Joe Bell]

Years ago I found a NOS block so I built it with out hardened seats, it has the Stainless steel valves that are hard and since then I have had to adjust my valves fro the hard valve pounding down into the block. Originally they had cast valves with a cast block to soft materials, now if you add a hardened material to a soft one what one will wear first? So I am with J&M on this one sorry guys!

[jsaylor]

I restored my 21 Touring in 1970. I run modern one piece valves, no hard seats, heavy valve springs, HC pistons, and Winfield Carb. I drive this car a lot. Multi day tours, Hot weather, cold weather and parades over the years. I have never seen any excessive seat wear. Still have 60 lbs compression. My 27 Tudor with A crank has the hard seats just because the machinist did it that way. The only extra cost was the price of the seats.

[BLB27]

Is any concern at all about the thinning of the block material due to removal for the hardened seats?

[Kevin Pharis]

If a conservative sized seat is used there is no concern of weakening the block. The main concern with hard seats is breaking thru to water jacket and springing a leak. There is plenty of room in the T block for hard seats when using the stock (or even slightly larger) sized valves.

One concern with hard seats is distortion of the cylinder bores due to the interference fit. Not really an issue... just do the seats before the bore and hone

[Adam]

Here’s a photo of a typical T block ready for new seats. There is generally no concern for thinning of the block.