I was reading the "Smokey Yunick's Power Secrets", and he said that all of the stress on the guides is at the spring side of the head, and that the port side can be cut way down, but he also said that it did close to nothing for port flow. He explained that if you could shink down and stand in the port that the air is still at the stem guide area.
These are his exhaust port thoughts:
"Many, but not all of the concepts that apply to the intake port will also be valid in the exhaust. Exhaust flow is initiated when the exhaust valve opens, and the relatively high pressure in the cylinder moves toward the relatively lower pressure area in the exhaust system. In addition, the pressure inside the exhaust system in a racing engine is usually pulled "artificially" low by the functioning of the headers. Therefore, it is generally possible to exhaust the chamber quite successfully with a rather small port.
The flow leaving the combustion chamber must get around the head of the exhaust valve before it enters the port, and the valve is the most important element in exhaust flow. Once again, it would be advantageous to have the port angle more nearly in line with the centerline of the valve, and the long and short sides of the port should be as nearly equal as possible. The flow will cone around the head of the valve as it leaves the chamber, but chamber-wall shrouding will sometimes break up a portion of the cone and reduce flow very considerably.
If at all possible, the exhaust port entry should be straight and concentric to the valve centerline for at least 1/2-inch before the bend towards the exit begins. If you cut away the short side radius and try to bend the flow right off the seat area, you will rip the side out of the cone and knock the flow down by at least 20-30 percent. Just as on the intake, the max flow will be achieved if the cone forms completely around the periphery of the valve head. If you set up the valve head and face properly, the cone can be shortened quite a bit, and once the cone closes up around the back of the valve head, you can pull the flow around the bend and send it out of the head."
He goes on in great detail more, and the intake discussions are in a complete differant direction that I would have ever imagined, ports are tricky, and common sense doesn't always do the trick here. I saw your cutaway pics on your site a couple of weeks ago and had been thinking about chopping up a head prior to that, but you pics did the trick, looks like your on track with the intakes, I think some narrowing on the valve half of the port might be benificial, but only testing will tell, I might have access to a flow bench soon, and I'm trying to get an engine Dyno together in the near future to try lots of things out, that's the only way to find the power, try anything and everthing and learn from failing which then becomes a gain, I'm sure there are lot's of things to be learned, so let's go!
Chris
