grinding out big valve head

["Eric Hedstrom" <eric_hedstrom@hotmail.com>]

Hello all,

Sorry about the fat fingers on my last post.

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!

Any advice on this procedure out there? Here's some concerns that came 
to mind while I was getting aluminum in my eyes. 

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?

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? 

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

4. Any tricks one can do to the exhaust passages (whats the official 
name anyway)? - it looks like there is A LOT of metal there before you 
get to the cooling passages - Is this a dangerous train of thought? It 
seems like there is a lot more metal between the coolant and the exhaust 
than the intake, why?

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

Sorry for the barrage of questions but I'm just winging it here. 

Thanks,

Eric Hedstrom, '82 bone stock (for now)


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