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What is porting?
Porting is the process of opening up an air pathway on an
engine.
Porting is done as a way of increasing engine
efficiency and
output. If you look at the image below you will see two
intake
runners. The one on the right as been ported while the one on
the
left has not. In another guide we will walk through the steps
to flowing a head and advanced porting techniques such as radiusing.
In this guide will will stick to the gasket porting
as it is one of the easiest jobs.
The
easiest way to
assure your ports match up is to use an old gasket. This
process
is known as gasket porting. If you look closely at the left
runner
in the above picture you can see the outline from the gasket.
If
you have this pronounced outline you can use it as a guide on what to
remove. If not you can bolt down a gasket as a guide and use
machinist's blue to make your own outline as shown below.
Dykem and Starrett both make excellent products for this.
Once you are sure what needs to
be removed, start by tapering the existing shape to your newly desired
shape, leaving just enough material to see the area you
painted. Do not worry about taper at this point.
Above you can see the mouth of
the runner opened up to the new size. You can also see the
transition is not smooth. Now is the time to
use your cutting tool to remove any extra material from the port and
contour a smooth transition. At this stage you are still
shaping. Do not worry about getting a smooth finish.
Once you have removed the extra material you will end up with
what is shown below.
Now using a 40 grit emery wheel
on a die-grinder, finish porting by removing any rough edges or
transitions you have left. Now is also the stage when you
grind of the extra material you left at the port entrance from the
first stage. As you achieve the final desired shape switch to a 80 grit
wheel to make any final adjustments. The final step I do is
to smooth the job out a little using 120 grit paper . You do
not want a polished finish only one that is free from bur or deep
tooling marks.
Once you have achieved a
slightly rough to the touch finish on the manifold you can move onto
the the head. Using the same gasket as a template now perform
the same process to the cylinder head. Remember to flip the
gasket over then marking the head other wise the ports will not line up
when the manifold is bolted up.
If you do not have porting tools this is a good kit to start with:
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