Burnt exhaust valves

Poulina

Poulina

New member
Tore down my motor after a recent valve job to build the bottom end.

The head recently had a lot of work done to it, +2mm valves, bowl work, etc.

Same machine shop that did the head work reinspects the head and says it's super warped and all the exhaust valves have purple/blueish discoloration on the edges, as seen in the picture.

The valves were sourced from Mountain High Performance. Did not use their valves seats albeit.

Valve lash was .08 and .18

This head had 4K miles on the rebuild before it was torn down again
 

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The valve seat contact width(how much of the valve that actually contacts the seat) was too narrow and did not allow enough heat to transfer to the seat/cooling jacket.
 
I'd be extremely surprised if Mountain High Performance had messed this head or valves up... Bill's probably one of the best engine builders/machinists around.
 
Yeah mhp didn't touch the head, I had local machinist do the work. I originally bought the valves and seats from mhp, only to use the valves because my machine shop deemed the seats as an inferior material and sourced their own.

They also are saying the valves are blueing because of inferior material quality (stainless steel vs inconel)

Im looking for some second opinions and/or past experiences with this type of situation

Thanks
 
Poulina said:
Yeah mhp didn't touch the head, I had local machinist do the work. I originally bought the valves and seats from mhp, only to use the valves because my machine shop deemed the seats as an inferior material and sourced their own.

They also are saying the valves are blueing because of inferior material quality (stainless steel vs inconel)

Im looking for some second opinions and/or past experiences with this type of situation

Thanks
Click to expand...

They aren't lying about the material. Inconel is the best you're going to get, but it's definitely not the only thing that works. Are there any other machine shops in your area that are reputable? I'd take it there for a second opinion.
 
The valve seat contact width(how much of the valve that actually contacts the seat) was too narrow and did not allow enough heat to transfer to the seat/cooling jacket.
Click to expand...
How are you so sure of this with out seeing a pic of the valve face? the picture of the seat looks ok to me as far as width goes.
 
Win slow said:
How are you so sure of this with out seeing a pic of the valve face? the picture of the seat looks ok to me as far as width goes.
Click to expand...

I didn't actually need to see any pictures at all, a description was enough to know it needs more seat contact. Not trying to be a know it all, I've just been rebuilding heads for many years.
 
I talked to rpm to see what they'd do to my head if I sent it to them months ago. Said they used powdered metal seats on cummins which kind of turned me off. That and they tapped the soft plugs for npt plugs and they broke 2 or 3 tap's doing it. Told him a metric plug with straight threads would go a lot easier lol.
They've got two guys on Instagram that put up detailed descriptions of what they do and I've learned a ton just from them. But I don't think they've got the fine details on higher horse diesels figured out just yet.
 
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