Hardened valve seats on the D2 head question

[rockittsled]

How can you tell if the hardened area is still there under the valves on a D2 head?  I am trying to find out for a thread on a another forum

http://www.ford-trucks.com/forums/1371069-valve-job-advise.html#post15274559

[Barry_R]

If you have a really good "touch" on the machinery, or are using a hand held grinder you could feel the difference in the way the material cuts.  But odds are most folks would never be able to know whether they made it past or not just cutting.

You would certainly know if the engine wore past that area though.  I have seen a few here that were really spectacular as far as wear goes.  But its really the exception rather than the norm these days to have them badly wear out.  Since these vehicles are mostly play toys instead of daily drivers or work vehicles they don't often see the level of abuse and accumulated mileage that they once did.

Personally I would rather try to use a slightly larger valve or play with the angles a bit to try and save that original seat if it were at all possible before I go installing seats.  There is not a whole lot of real estate between the seat and water in some of those heads, and significantly breaking through pretty much ruins the casting.  On the bright side - D2 castings are still pretty common and inexpensive - so swapping to another one is a viable option once you've worn one out or damaged it beyond salvation.

[rockittsled]

Would a Rockwell hardness-type tester be able ID the area or even a scratch test using a scribe?

[Barry_R]

Scratch maybe but won't show the available depth, an indent tester would give you an answer but might wreck the surface.  Neither one is optimal for measuring depth in a non-destructive manner in a part you need to use.

What are you doing answering questions at 5 AM?

[jayb]

LOL!  The FE guys never sleep...   

[machoneman]

Hah....never sleep, indeed!

[RJP]

As Barry said one has to have a good touch to be able to tell if a seat is hardened. What I do is if the head is supposed to have hardened seats I lightly touch the seat with a gray finishing stone to see if it cuts or just sort of polishes the surface. The cutting sound and feel also will be a little different than on a seat that is plain iron. Most hardened seats should clean up with just a light surface cut and have little or no pitting normally found on unhardened seat. I recently did a set of D2 heads and the exhaust seats cleaned up with just a light touch of the stone. Be careful as the induction hardness is very shallow and any thing beyond a light, quick cut of the stone will grind thru the hard surface.

[Joe-JDC]

If you are lucky when the heads are cleaned, there will be a discoloration in a circular pattern around the exhaust seat area that has a blue/black tinge to it if the hardness has not been cut away.  Looks like a piece of metal that has had a torch taken to it and then quenched in oil.  You can visually notice the difference on a fresh/new head.  Joe-JDC

[cjshaker]

What are you doing answering questions at 5 AM?

LOL...never sleep indeed!
That's only 2 AM Pacific time. Shoot, I'm just thinking about going to bed then to get my 4hrs of sleep.

I have to ask though, knowing that induction hardening involves an electromagnetic process, how do you use an electromagnetic coil on a valve seat? The area to be heated must pass through or be inside the coil to be heated. I don't see how this is possible. Some sort of external heating device seems like it would be the only way, such as a flame or something similar. Which begs the question, could heating the seat slowly with a torch and then quenching it re-establish the hardened surface? I know iron is tricky to heat and cool, and it would hardly be worth it to try, I'm just wondering out of curiosity.

[Barry_R]

Never saw them do a head.

But I did see them do induction hardened Chrysler cams by lowering them through the magnet coil using a stepper to drop them vertically one lobe at a time. 

I'll bet they drop the coil into the valve pocket...some of that factory stuff is really cool to watch and surprisingly creative.

[cjshaker]

Electromagnetic coils only work by the piece passing THROUGH the coil or rotating inside it. The field that generates the heat is within the circumference of the coil, at least to my knowledge. It would be interesting to know how it's actually done.

[rockittsled]

What are you doing answering questions at 5 AM?

I work 2nd shift and don't normally go to bed till 5 or so EST

[rockittsled]

Also, thank you for the answers

[Qikbbstang]

Always wondered how the electro-hardening was done on cast iron heads. I vaguely recall the later Cleveland's (D1ZE) like the 351CJ/HO's had hardened seats. In place hardening a cast iron head's seats is remarkable when you think about what usually is required to harden metals. Odd that FoMoCo did not do many other motor's or maybe they did?