[TR] Hardened seats and cracked heads

[Bob]

On Monday, November 22, 2010 03:32:47 pm fogbro1 at comcast.net wrote:
> List,
> 
> 
> 
> A machine shop is telling me that they will no longer install hardened
> valve seats in cast iron heads because doing so substantially increases
> the chance of the head cracking. Supposedly (they say) this is even more
> risky with highly tuned street or race engines. Are they blowing smoke or
> is this true? Comments......
> 
> 
> 
> Ed Woods

Ed,

I have the hardened seats installed on my 3, 4 and 6. So far with the 3 and 4 
no problems. The 6 motor only has about 1 hour on the engine so it is to soon 
to tell.

The machine shop I use said nothing about the process when I dropped the heads 
off. No cautions, etc.

The 3 engine is 87MM otherwise stock. The 4 is stock all the way and so is the 
6. Minor head shaving just to insure a flat surface only.

Maybe their concern is the seat will expand and contract at different rates 
than the surrounding cast iron? But if so, wouldn't my machine shop know of 
this and refused?

Curious to hear other replies.



Bob