Re: grinding out big valve head

[skerocdriver@juno.com (Shawn C Meze)]

On Fri, 12 Dec 1997 12:10:10 PST "Eric Hedstrom"
<eric_hedstrom@hotmail.com> writes:
>Hello all,
>I took a first stab yesterday at porting/flowing/grinding/polishing (or 
>whatever you want to call it) the head from the JH which I plan to blow 
>(re the G60 cam short-lived thread). I couldn't believe how rough the 
>stock casting is - it looks the same as the coolant channels!


Its amazing how bad some of the stock factory castings are. 



>1. I tried to smooth out the inside bend on the intakes so the air 
>doesn't turn as sharply. How much meat can I grind away?


Not much. Take a gasket as a template and scribe around the opening. All
the meat inside the opening can be removed. This is known as match
porting. If you don't have a flow bench, you really don't want to remove
much more than that. (Because you wont know if you have made all the
ports the same size, all the way through.) Just concentrate on getting
the ports smooth. That in itself will do alot for the way the head flows.

While your at it, do the same thing to the intake manifold and GL on
doing the exhaust manifold! Its hardened steel and is really hard to cut.

don't get in there and start hogging out material as you can make it much
worse than it is in its rough state. 


>2. What the heck are those numbers on the inside of the intake ports 
>(10,12,11,9)? Is it just something from the casting process? 


Good question. 


>3. It's pretty hard to get at the surface around the valve guides is 
>it worth it? 

If you can get in there and make it smooth, then it is worth it.


>4. Any tricks one can do to the exhaust passages (whats the official 
>name anyway)?


Exhaust port(s)
Not really, do them the same and notice that the metal in these ports are
a little harder to work than the intake. 

>5. What kind of performance gains are typically seen from a port and 
>polish? 


Free flowing makes more power. It helps the engine to make more power,
easier. You might even see a gain in fuel economy, if done right. 



              Shawn Meze
86' Jetta GLi           82' Scirocco GTi
The Fastest, Quickest, Cleanest and
best looking Scirocco in all of San Diego!
http://www.Geocities.com/MotorCity/Speedway/1308/index.htm
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