Magnum Head / sunk exhaust valve

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360duster

360duster

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Hi Guys,

damaged one head while Opening up pushrod pinch, got another used one to complete….i removed the valves and found all exhaust valves totally sunk….what does cause this??

I notice this heads iron is much more softer than the other head i did….and it´s far better casting Quality (too bad that every seat is cracked and the seats are so deep)….

use it or scrap it? Budget build….i´ve used heads with cracked seats before, just did not see such deep seats before.

Thanks Michael

20200125_195545.jpg
20200125_195555.jpg
 
If it's not cracked, you can put seats in it. Some of the heads of that era didn't get a decent heat treat in the exhaust seat.

If they ain't fractured, they ain't junk.
 
Man. Look how wide the intake seat is in the 2nd pix.....wonder if that head ran really hot to do that....

The insert will have a bit wider load bearing area in the head material than the valve will typically ever have. That's all you can count on to keep it from sinking as badly. But how far you can cut things down from where the exhaust side is and not get into the water jacket, IDK.
 
take em to a shop, they are the pros. Ask if they can cut and press in some new seats. Many magnum heads have that crack, and many still work fine.
 
Isn't the sinking caused by lack of lead in the fuel? I believe a set of hardened seats and you're in business.
 
69 M-CODE CUDA said:
Isn't the sinking caused by lack of lead in the fuel? I believe a set of hardened seats and you're in business.
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It is, but that head should have been induction hardened in the exhaust seat area. It is possible that the load on the engine made enough heat to beat the seats out of it.

I've literally installed thousands of hard seats. A Ford FE engine was made in the tens of millions and not one had seats for unleaded fuel. That and all the other heads that need them. If those heads ain't fractured, put hard seats in there and forget it.

If you can't find a shop that will mag the heads and do it, find another shop.
 
dura bond powdered metal seats -the premium ones
maybe someone did a vj and went through the induction hardening which is not very thick
then better than new
pt & mag
 
It's called valve seat recession and it's caused two ways. By running a dirty air filter and improper heat treat. From those pictures, I'd say the first, since the intakes are bad too.
 
Hi Guys, thank you very much for your thoughts.

since machine work is pretty expensive over here i´ll search for another one.

Michael
 
Just noticed that the intake valve guide in the 2nd pix is oval, not round. Never seen one that bad. No wonder that intake seat is so worn and much wider on the right side than left. This does not look to me like just a lack of induction hardening.. the whole casting appears soft. Or someone ran some darned stiff springs in this head.
 
Every magnum head I’ve ever seen that came off a motor that was in a vehicle that was actually used as a “truck” had exhaust seats like that.

That’s not a unique situation for Magnum heads either.

I had some Ford Windsor heads in here a year or so ago...... some of the exhaust seats were sunk nearly a 1/4”.

I’m not going to get into a big debate about it, but in 30 years of being in the cylinder head repair business...... it’s actually not at all uncommon to see heads like that.

The chamber in the lower pic looks like it’s probably cracked where the two valves are closest to each other.
 
Here’s a J head with maybe 10k on it since it had its last valve job...... then I put a seat in it.

9C46A050-C612-40F5-A907-98314CBED8D9.jpeg


F588FB9F-66C5-4B6A-827C-73CBA9CCCBF9.jpeg


211EFC6C-28B6-44AE-B3D9-A94ACC4E6BC5.jpeg
 
If you get new seats installed make sure your guy knows that the water jacket is much closer to the bottom of the seat than a LA cylinder head.
 
PRH said:
Every magnum head I’ve ever seen that came off a motor that was in a vehicle that was actually used as a “truck” had exhaust seats like that.

The chamber in the lower pic looks like it’s probably cracked where the two valves are closest to each other.
Click to expand...

You are right Dwayne, it´s cracked. The other three at this head also. I checked with a carbide, this heads cast iron is really much more softer than another set i worked on. Easy to work on, but not very durable.

Michael
 
360duster said:
You are right Dwayne, it´s cracked. The other three at this head also. I checked with a carbide, this heads cast iron is really much more softer than another set i worked on. Easy to work on, but not very durable.

Michael
Click to expand...


That's a bummer. Now they are boat anchors.
 
360duster said:
Hi Guys,

damaged one head while Opening up pushrod pinch, got another used one to complete….i removed the valves and found all exhaust valves totally sunk….what does cause this??

I notice this heads iron is much more softer than the other head i did….and it´s far better casting Quality (too bad that every seat is cracked and the seats are so deep)….

use it or scrap it? Budget build….i´ve used heads with cracked seats before, just did not see such deep seats before.

Thanks Michael

View attachment 1715458765 View attachment 1715458766
Click to expand...

You can probly have new hardened seats installed and raise them back up where they belong. Sunken seats are h.p. killers for every thing but a hemi.
 
yeh but the only reason I sink them in a hemi is to keep them from hitting each other - else spread the lca-- or both
then raise the compression MAKE IT STOP
 
Wyrmrider said:
yeh but the only reason I sink them in a hemi is to keep them from hitting each other - else spread the lca-- or both
then raise the compression MAKE IT STOP
Click to expand...

I had to back clip the valves too---------
 
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