Valve seat rim sitting proud in chamber - Detonation risk?

[Nut124]

One exhaust valve seat insert sits quite proud in the head chamber. The seat edge is sticking up about 10-15 thou. This chamber is also a bit ugly looking, with some pitting.

Could the Ex seat rim sticking out be a detonation source?

See pictures below. Should I have the seat cut deeper so the rim is flush with the casting? The other chambers look a lot better.

[BillK]

Cutting it deeper probably will not help. Looks like the seat is a little too small for the valve size. I have seen them like that a few times and they dont seem to cause a problem.

[Cubic_Cleveland]

I’ve seen this issue many times on factory stuff. Seems core shift isn’t accounted for or something. The chambers get deeper in relation to the deck, while the seat ring stays the same height. Never seems to be an issue on standard applications, but I don’t like it either..

[mag2555]

There is not from what I can see in those pictures enough wall thickness left in those seat incerts to not have then drop out soon, be sides move around a bunch before they do so!

Also with the geometry that's there your compromising much needed low lift air flow that the motor cannot make up for if the compression is under 10.5 to one.

You need to get bigger OD seat incerts installed ( and deeper ones at that! ) and if besides what I posted about there is a hot spot issue, then that will go away also.

[jed]

Be careful putting in a larger valve seat and sinking it deeper there may be water close???
it appears from the pictures that coolant has seeped in to the cylinder probably from a bad head
gasket sealing. in picture number one at the top there shows pitting just above the seat ring and
it can be seen in the other two pictures the valve sealing angle of the seat appears to have slight pitting
also. If the budget allows I would touch up the valve job and surface the head. I would bet the ex valve
out of that cylinder has rust Pitts on it also

[allencr267]

Looks about a too wide 60 degree seat, is it the pic's distortion or for real?
//
Also from post viewtopic.php?f=1&t=61263
'owner said his mill will produce a flawless finish.'.

[Ks Fats]

Pressure check the head before you go any further. I've seen that rust pattern on heads that had been cut into the coolant passage when installing seat inserts. Hard to tell from the pics but there seems to be some erosion between the seat and the casting. Might help if we knew the casting # as some were worse than others in this regard; on some it was safer to remove material from the flat side of the insert on a lathe before they were installed. Had to tell more than one person that his prized 461 heads were now junk because the seat inserts were leaking. In some cases they can be repaired but most times it is cost prohibitive.

[Nut124]

Thanks for the replies.

I took the head to an old timer machinist. He says the pitting, damage is from water. That cylinder did have a head gasket water leak some years ago.

He suggested cutting the seat down a bit with a 90deg cutter, then recutting the seat.

These seat are regularly cut to the limit for bigger valves and dropping seats is not common from what I read unless something else is wrong.

Below are some better pics.

[ProPower engines]

For the time it will take to correct the issue I would replace the seats.
I have seen this before on some engines and even though it seems fine the erosion between the seat and the casting can be greater then you think. the last head I seen did drop a seat a few months later cause the customer did not want to replace the seats.
When it came back and I cut out the other seats there was rust and corrosion all the way around the other inserts
as well as starting to go underneath the seats.
Now's the time to decide on that part but its your call if its about doing it right the 1st time.
Besides from the pic's it looks like it can do with a valve job anyway.

JMO

[Nut124]

Where would I get the seats - any idea?

My machinist said he didn't think his regular source would have the size.

[ProPower engines]

Where would I get the seats - any idea?

My machinist said he didn't think his regular source would have the size.

Figure out what OD and ID you need and call Durabond. They have an excellent selection of small seats.
Use the 7000 series they last longer in HP applications.
SBI will have something as well. Just look up what you need by sizes and ask for the part number. Or make the phone call.

the seats should be pulled out to start with then decide if you need a .010 or .020 larger OD to fix the issue.

[Nut124]

Looks about a too wide 60 degree seat, is it the pic's distortion or for real?
//
Also from post viewtopic.php?f=1&t=61263
'owner said his mill will produce a flawless finish.'.

It seems to me the 60 deg cut was never there or has eroded away. The cut you see is the 45.

The head surface is perfect now. What you see on the surface is carbon fouling, oil that I tried to brush away from the chamber before the pictures.

[MotionMachine]

Where would I get the seats - any idea?

My machinist said he didn't think his regular source would have the size.

If your machinist can't modify an existing seat to fit, you need a different machinist. If it makes you feel any better, every Alfa head I do has protruding seats, intakes worse than exhaust but exhaust do it too. When I have to install seats in a head that has had the seats sunk way past what is reasonable, to restore the tip height, I often have to leave the seats proud of the chamber floor. But I radius the corner of the seat before installing them so there is no sharp edge.

DSC01451 (Small).JPG

[Walter R. Malik]

If you use a good enough fuel it should not be an issue
I have seen that, (with the seat being even more proud), help the back-flow, reversion issue that a big cam can present.

[mag2555]

I would look into Martin Wells brand seats and have a bottle of Goodson supply FW-2 fluidweld on hand to bring to the shop doing the seats along with the heads.