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What happens if you don't get hardened seats....

In the grand scheme of things, installing hardened ex seats is a pretty small add-on to the price of rebuilding an engine.

I’ve had heads come in where the ex seats had about a 1/4” of recession.
WaaaaaY worse than the OP has here.
 
Not sure I have pictures, but the exhaust valves were sitting noticeably lower in their seats when I rebuilt the 383 in my 67 Satellite in 1990 at 117k miles. Most of the ~25k miles I put on it beforehand were on unleaded without additives. Previous owner put about ~12k on during his 4 yrs with it and he told me he ran it on whatever he got at the pump. I had hardened seats installed during the rebuild and no obvious recession now at 148k. Cost of adding new seats during rebuild was a very small percentage of the total.

I am finding other issues during teardown, but those are covered in another thread.
 
Of course, not all machine shops provide the same level of work, and I’ve seen plenty of ex seat installations that weren’t great.
Here’s two lovely “flow enhancing” examples-

I particularly like the peening of the lip around the seat insert on the second pic.
Oh, and both of these examples(two different pair) happen to be T/A heads.

IMG_3821.png


IMG_3822.png


As ugly as they were, they weren’t loose or leaking…… and they were a larger OD than are recommended ……. And they were T/A heads………so I left them in place and just did my best to blend away the step that was left by using inserts with the ID way larger than the original bowl diameter.
 
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That seat has been cut way too many times!
 
For what it's worth, I've seen a few heads with seats so wore out that the springs could rotate with ease. Hardened seats weren't too expensive to put in. Sometimes it's a matter of whether the head will take it or not.

I had a set of 340X heads built with intentions of installing hardened seats, but there wasn't enough material left in the head to hold them.

I just run lead substitute in every fill up and don't drive the car every day. It's a small price to pay for cheap insurance.
 
I like to use seats with the ID sized close to the bowl diameter of the head they’re going in……

image0.png


image1.png


image2.png
 
What type of material are the seats made of that look like bronze color? I've seen pictures of them on
Mopar Nascar heads and always wondered?
image8-copy.jpg
 
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I wish I could get leaded around here!
 
I have four cars with 55 to 60 year old motors in them, daily drivers, no rebuilds, some get a lot more miles than others. Wonder how sunk the valves are.
 
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