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3 minute(s) of a 113 minute read
7-30-2014
Now here's the most important thing for me (and hopefully for you!) in this thread.
I've tried to combine some of my knowledge and explain you how to port and increase horsepower of a Nailhead engine, but the basic principles can be applied to any other engine (a 455 maybe, hehe!).
The basics and intake ports:
I'm sorry that I've lost some words during my explanation, it was a little difficult since I haven't recorded English-speaking videos for a while.
After you talk for more than 5 mins during recording everything becomes a little messed up, especially when it's done at night, lol.
Here's the 2nd part about the exhaust ports...
...right after which my camera ran out of juice. So the ending is a little strange. 
Exhaust port related video.
This video shows the original port exit angle and a flat step which occurs when you try to line it up to the gasket.
This exhaust port curve was discussed in the previous - exhaust guide - video.
Combustion chamber video.
This is an old video, when all 8 combustion chambers were pretty close to equal, while still being very rough.
But you can see the way it's done as the shape can be seen better.
Warning: again my background soundtrack is somewhat crazy, this time it's a sort of norwegian black metal, which is good for porting cast iron heads in cold winters. You obviously need some hate to get a cast iron head done, haha.
So please, be ready to adjust the volume. No explanations given there.
The idea is to gradually unshroud both of the valves - move the walls a little further apart from the seats and remove sharp edges. The result is a little bigger combustion chamber on the intake side, than on the exhaust - because the intake valve is bigger and you shouldn't increase the chamber more than necessary. Same in a word of head porting science is that you don't need more than 6.5 mm (0.255 in) valve-to-wall clearance as it would have no reaction on performance.
p.s. Sorry for creating a bunch of messages, but I can't get more than 1 video per message.