Flathead valve seat question

[harleycontracter]

I'm trying to understand ...I found a guy to repair the 1 valve seal seat with an oversize valve seat. My valve seat came loose and landed around the valve stem. What causes that ? No cracks around seat that I can see motor wasn't sized. Is that a common thing to happen? Would it necessarily mean others could free up ? Thanks

[Pete]

Originally Posted by harleycontracter

I'm trying to understand ...I found a guy to repair the 1 valve seal seat with an oversize valve seat. My valve seat came loose and landed around the valve stem. What causes that ? No cracks around seat that I can see motor wasn't sized. Is that a common thing to happen? Would it necessarily mean others could free up ? Thanks

Usually in a case like that, the ring was not installed with enough press.
Should be .006 for cast iron.
Others could loosen if not installed properly.
Installed right, they will last forever.

[Newc]

WE used to freeze the seats and heat the block. With white lead lube they would drop in sizzle a bit and were forever. Newc

[vincent]

On my motorcycle cylinderheads I use a simple formula: 1/275 oversize on iron heads , 1/250 on aluminum heads. To make sure the seat is falling into the recess I do the same as Newc

[fredeuce]

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I recently went through a similar repair. This was on the No. 6 Ex valve. I did observe that the valve was burnt on two spots roughly 180 deg apart. I also observed that the stems and guides were badly worn. I could only conclude due to the wear on the guides the valve was not returning to the seat properly and allowed exhaust gas to pass causing the valve to burn and over heating the seat resulting in a loss of radial tension. I would be grateful for any alternate views on this.