Now that the heads are apart, I can
start working on porting them. If you look at the exhaust port below,
you'll see some casting flaws (like high spots or things that look like
there growing). These all disturb air flow and hold heat which is
something I don't want because of how much compression I have. If these
were to hold heat, they could cause "pre-ignition" which is
when a engine tries to run when you shut it off. These areas hold in
heat that ignites the fuel causing the pre-ignition. My goal is to remove
all these flaws and polish the exhaust ports. It's not a good idea to
polish the intake ports because of the way the air-fuel flows. Those
ports will be handled a different way.
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I bought this kit that has different
size sanding drums. Some are cylindrical and some are pointed. Most fit
on the mandrel shown below to reach into the ports. The mandrel has
threads on the end and the drums just screw on by hand. This process isn't hard
but is very time consuming. Taking your time here is the key if you want
everything to come out nice.
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Oooohh...shinny....now that's what I'm
talk'n about. Believe it or not this is the same port as above. Looks a
lot better now that its polished and it should flow much better than
before. To get the port to this point, I had to use two different shaped
sanding drums and two different grits for a total of four different
drums in all.
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This is a shot of the same port but looking in from
the combustion chamber. This was a challenge to not hit the valve seat
here because the dummy valve had to be removed to work inside. I didn't
hit anything because I took my time.
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