Hello from Germany,

My Valve Guides are worn with clearence of 0,007".
The actual Valve Steam is 0,3414 and i am looking to ream the guides to 0,373 to use Valves with 0,372 stem. Is this possible with this heads?

Thx

Danny

 

.001 clearance on the exhaust is not enough. Just barely enough for intakes. I'd want more.

Verify that you can't get valves with slightly oversize stems. These used to be commonly available--.003--.015 oversize. They may/may not be available any more. I haven't looked for them in years.

https://www.enginebuildermag.com/200...econditioning/

Alternative is to install bronze liners in the guides. Any machine shop should be able to do this.

For ****'s sake DO NOT have the guides knurled.

Any repair--reaming WAY oversize, reaming slightly oversize, installing thinwall bronze inserts (or even knurling)--will require cutting new valve seats to ensure concentricity.

And if the exhaust seats are cut too deeply, you cut through the induction-hardened layer leading to rapid exhaust seat erosion/recession. So hardened seat inserts would be needed if the exhaust seats need much more than "touch-up" cutting.

Now you're starting to understand why aftermarket aluminum heads are getting so popular. By the time you pay a shop to rebuild iron OEM-junk heads, you're well on the way to buying aftermarket heads with more potential and less weight.