Re: D-port heads - std to modified.
OK, I had a sequence of pictures, but the forum will only allow a URL. That's going to be too much work.
The plan is as follows:
Test std unmodified ports. To be honest they are pretty ordinary as per Ford of that era. The seats and throat are cut with no thought to blending into the casting. There is some core shift, but heights are fairly uniform. The short turn radius had a very sharp edge - The exh port is better here, again as per my exp of Ford of the era. The port is a swirl design, I assume intentionally, though the swirl is biased to the cylinder wall, which is the reverse of desirable. To be fair to the designers I'm not sure swirl ports were well understood at the time. The inside wall of the port has a large hump in it, prior to the bowl. I cannot see any real reason for this, but I think this is part of the reason for the flow bias at the valve. Straightening this out may help a lot. Curiously not all of the ports are the same shape - the rear-most ports of both cylinder heads have more significant 'humps'. The inlet manifold also showed flow bias when looking at the carbon deposits and where wall washing had occurred. The inlet ports were also a poor match to the head ports, being significantly larger - a 2-2.5mm step at some points. The rearmost port/manifold may have the worst combination of flow bias from manifold to port - the flow appears biased to the weak side of the port - perhaps this is the reason for the slightly different shape.
I'll use some silicone to make castings of the ports. I'll check my observations of the port shapes, the castings will allow for some accurate dimensions to be taken without the need for special tooling.
I have been offered access to a flow bench, so the plan is to flow a stock port, warts and all. Blend and clean up a port and valve and flow and then use a 44.5mm intake valve to do the same. I'll flow a std ex port as well.