are exhaust port templates sometimes required?
At Stahl Headers, our two
primary goals are quality and performance. This often requires
taking extra steps in order to achieve the best possible results from your
new Stahl Header. Exhaust Port / Header Flange mismatch is one of
the quickest ways to rob horsepower. Therefore, we take port
alignment very seriously.
To demonstrate this, a dyno
test was conducted using two identical style headers on a Chevy small block
engine with spread port cylinder heads. One header had standard Chevy
small block 23° flanges, the other spread port Chevy small block
flanges. The end result was a loss of more than 40 horsepower due to
the incorrect port alignment.
example represents the center two exhaust ports of a standard Chevy
23° small block cylinder head.
you can see from the overlay, there is a severe mismatch of the port
alignment between the standard exhaust ports and the spread port
flange. Another consideration is that each manufacturer often
produces their own unique port shapes. Raised port cylinder
heads, ported cylinder heads and other factors can also result in
improper port alignment. Therefore, choosing the correct
flange is critical.
taking the additional step of asking you to provide us with an
accurate port template, we remove any uncertainty as to whether we
are choosing the proper flanges for your application.
It is this attention to detail that
results in the superior level of performance and quality for which
Stahl Headers has been known for over 40 years.
How to create a proper
Customers often tell us that
their gaskets are a perfect match to their cylinder heads. We have yet
to find this to be true. It is critical that we have an accurate representation
of the location of both the exhaust ports and the bolt pattern. Faxed
templates are not acceptable as this process will distort them.
Mailing us a hard copy is the preferred method. Therefore, we ask you to please follow the following
guidelines when preparing your port template.
best. We have found that manila file folders make an excellent choice. Anything
heavier than this is not recommended. Cardboard, heavy poster board,
etc., will not punch out as cleanly, is more difficult to work with, and
will not give the desired result.
|Position the paper
over the cylinder head, making sure that all ports and bolt holes are
covered. (If you are using a file folder you will need to
turn it on an angle to cover all the ports and bolt holes.) Once
you have your material in place, use tape to secure it to the cylinder
|Using a small ball peen
hammer, carefully tap around the first bolt hole until the paper has been punched
out (see insets in fig.2).
Insert a header bolt and
snug it down enough to securely hold your template in place (fig.2).
|Repeat this process for all
of the remaining header bolts (fig.3).
|Once all bolts are in
place, carefully tap around the edges of each of the exhaust ports until
the paper has been cleanly punched out (fig.4).
|After you have completed
your template, be sure to write on the outside of the template as to the top and/or bottom. You should also
indicate the type of cylinder head the template was made from, as
well as your name and contact info. For mailing purposes you
can trim away the excess paper (fig.5).
Mail the completed
Stahl Headers, 1515 Mt. Rose Ave., York, PA 17403.