Valve Stems

[FirstEliminator]

   hey guys,

   A while back I made a post about seat and guide machines. Well, I finally bought one. Along with Sunnen's Complete Cylinder Head and Engine Rebuilding Handbook. It's a good book that has shown a lot of info that I haven't seen elsewhere.  While trying to figure out what I need to rebuild some of the cylinder heads I have laying around a thought had crossed my mind. If one is replacing guides and valves on an FE head. Would it make sense to go with 11/32 valve stems on a stock or mild performance engine?  Assuming FE sized valves are readily available in 11/32 stem size.

   thanks,
      Mark

[blykins]

Yes sir, it's an excellent upgrade. 

[Falcon67]

I might go looking for that book.  $$$ but I found a digital seller here - http://www.abrasiveengineering.com/bksunn.html

[FirstEliminator]

   It's a great book. Kinda pricey, but worth it. I found mine on Amazon for $169.

    Brent,
      Are say perhaps CJ diameter valves available with 11/32? Or do the larger valves have to be cut down to size?

 thanks,
   Mark

[blykins]

You can pretty much get any FE sized valve in an 11/32" stem.

[FirstEliminator]

  I've been acquiring tooling and getting the seat and guide machine set-up. Increasing the valve size of course has the benefits of better flow. What other mods are needed to support the larger valves? I'd suspect opening up the bowl? area above the seat a bit would help. As I've read, that area should less diameter than the seat to provide a venturi type effect. Is there any round-about percentage for that diameter in relation to seat size? If so, would it differ from intake to exhaust?

[jayb]

You want to hang right around 88% to 92% of the valve diameter for the diameter of the throat under the valve.

[FirstEliminator]

   Thanks Jay. Here is another thought. I saw a youtube video of a guy rebuilding 390 heads. He put in hardened exhaust seats and then used a bowl hog to open the bowl to the diameter of the seat for a smooth transition. My thought was I could use a boring head to open the bowl into a cylindrical shape. Or, if a bowl hog was used it would taper the top giving the bowl an inverted barrel shape. Do you think one shape would be preferred over the other?  I have several boring heads, but no bowl hogs.  Hopefully I don't annoy to many with my questions.

  thank you,
      Mark