Quick question, im portmatching some L67 heads, there is a TON of material that needs to come off to match the gaskets, which are close to the manifolds.

Is there any danger in opening the exhaust ports too much? Are there coolant passages or anything near them?

don't gasket match. You need to match the diameter of the port to the diameter of the manifold. The gasket squashes down when it is tightened and you won't get a smooth surface if you gasket match.

Hope this helps.

And, yes you can over port. Check the diameter of the exhaust manifold inlet and go from there.

Arn

Im using metal gaskets, so squashing wont be an issue, and hoging out the manifolds to match.

My main concern is if im going to hit a water passage or anything.

As far as how anyone does it, lol, I dont think it matters, the stock ports are so pathetically undersized, I dont think there is any amount of screwing up you could do that still wouldnt be an improvement.

I have a bunch of good head porting information... I am going to keep looking for it but here is a starter thread to look at.

http://www.clubgp.com/newfo...e=&smode=&s=#4828430

Here is a picture of the exhaust port.... The amount of material you can remove to increase flow is minimal.

[This message has been edited by darkhorizon (edited 05-31-2009).]

Now THAT is cool! Took me a minute to figure out exactly where I was looking at.

DON'T open up the bottom floor of the exhaust ports. You want that to be the flat part of a D shape.

Try this:

http://www.zzperformance.co...php?id=208&catid=110

quote Originally posted by Jncomutt: DON'T open up the bottom floor of the exhaust ports. You want that to be the flat part of a D shape.

while you should not open it up, you can make it larger, but still maintain the shape.