Is it safe to open up the center exhaust port flange area to 1-3/4"? From reading the Bishop/Tardel book, Mike talks about only taking out 1/16" if that. Am I right to think he's talking about the narrow area around 3-4 inches inside the port?
Tex Smith's book about Flathead's also shows a divider being installed into the center port. It's logical to ***ume that to compensate for the divider width, the port can be opened up by some amount. But it doesn't say by how much. The exhaust port walls are pretty thick and I remember somewhere online someone cut a block up to show the thickness.
Thanks CNC, I've searched many hours here looking at pictures and cut away blocks. There's a lot about intake ports and the outer exhaust ports, some pics of the roof and floor of the center port, but I haven't been able to find a pic of the side wall thickness.
The top and bottom of the center port are exposed to water inside the jacket area, but the sides of the ports are solid until they break thru to the inside of the adjoining cylinders. So the port thickness in that axis will vary depending on what bore size the cylinders are. And since huge overbores are common in Flatheads that would be the area of the most concern. If you do find pics of this, make sure you share, i'm sure others would like to know as well.
This is a decent picture showing the sidewall thickness (upper right side of picture). Cant tell if the cut was in the middle of the exhaust port though.
I did some porting in the exhaust flanges on my 8BA All I did was what Abbin suggested in his book. Check there too in your research.
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