WOW!!!! The intake valve has NO seat at all!....and no apparent damage to
the head, cylinder, bore etc!!!!! amazing! as if the material of the seat
just disintegrated..
-------------------- Clip ---------------------
I've seen seats dropped back into the heads many times.
Here is what I was told by an aircraft cylinder head rebuilder.
"If the heads were welded with standard aluminum alloy then it expands at
a different rate than the original alloy and there are heat differences".
On heads he rebuilt for me he cut some fins off the cylinder heads for
welding alloy, he claimed it was the only way to match the alloy.
Doubt Me?
Try the center punch test on welded up heads and you'll see that all
welded areas are harder that the OEM aluminum areas. A brinnel test punch
is more accurate but not necessary.
I've never done this on AMCs so I can't speak for them.
The argument is that weak lifters, badly adjusted lifters can cause hard
closing of valves and start this process of loosening the seat, the seat
then is flame cut enlarged over a period of time and drops back
completely eventually.

Stan Wilder

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