DIY head porting with a dremel?

[nealtovsen@yahoo.com (Neal)]

There are two basic categories of porting jobs. A "port matching" job only
matches intake/exhaust manifolds to the head ports and can be done
relatively easily yourself. A true head porting involves completely
re-shaping the ports, valve guide fixtures, valve seats, combustion
chambers, etc. A "street port" is usually a port matching job with some
additional work, but nothing major.

It is possible to get good results from a mild street port yourself with a
grinder, dremel, etc. Check out the latest issue of Grassroots Motorsports
for a good overview.

Full head porting is a major "black art". Doing it incorrectly can cause you
to LOSE horsepower, or change the power characteristics such that they don't
suit the type of driving that you do. Not advised unless you have three or
four spare heads laying around that you can practice on.

IMHO, the only two good options for a FULL porting job are to trust it to an
old geezer who has been doing this so long that he has attained "guru"
status and has dyno charts to prove it, or to have a (still experienced)
person use a flow bench to validate and document a proper porting job. The
best option is to find a guru with a flow bench. :) Expect to pay major
scratch for this, as it is VERY time consuming. The head for my '77 is
currently with a guy who has both flow numbers and dyno charts to backup his
work. Unfortunately, the flow numbers and dyno charts didn't depict the six
months it takes the guy to get around to doing the porting. <sigh!>

Neal

> -----Original Message-----
> From: scirocco-l-admin@scirocco.org
> [mailto:scirocco-l-admin@scirocco.org]On Behalf Of T. Reed
> Sent: Saturday, August 31, 2002 12:12 AM
> To: scirocco-l@scirocco.org
> Subject: DIY head porting with a dremel?
>
>
> Okay, well this is gonna sound stupid coming from an inexperienced
> youngin' like me.. but..
>
> With everybody running to pay a shop hundreds of dollars to get their head
> ported, is there any reason I can't just do this myself?
>
> I mean.. looking at before and after pictures of 16v intake and exhaust
> ports on people's web pages, it looks like somebody just took a dremel
> with a grinding bit and opened up the ports a little without making the
> outside surface any bigger. I consider the dremel tool to be the
> handyman's 3rd most important secret weapon (after vice grips and duct
> tape) and I feel quite confident with a dremel in hand. I don't see any
> reason why I couldn't just duplicate the re-shaping of the ports as shown
> in the photos myself. Or is there something more to this that I'm missing?
>
> Why do people send this work away to be done by professionals? Is it the
> risk of taking off too much material and ruining an expensive 16v head?
> Fear of screwing it up and actually reducing the engine's power? Or is it
> just a sense of "if you're going to do something, do it right"?
>
> Maybe I'm being stupid here and grinding material away like that only
> helps if you put bigger valves in too..
>
> Being a cheap bastard, and being that I'm going to be pulling my head
> real soon now anyway to put in a 2 liter block.. I just have to ask
> because if $20 worth of dremel bits will buy me some more ponies, I'm
> game.
>
> -Toby
>
>
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