Hey all,
Bernd is right on! Dont go near the plates and bores around the plates and
you will be much better off. You need to keep the amount of air going in
the TB at idle the same, which means the plates have to mate with the bores
the same way (they dont touch, but they are close). The riodges that you
want to remove are there to linearize the response of the butterfly valve.
A linear response is much easier to use for programming, and will give a
smoother off idle performance. The first 15 degrees of rotation of a
butterfly valve provide the largest amount of airflow rate change. The
ridges shroud the first 10 or so degrees of rotation, blocking the flow and
reducing the flow rate increase per degree rotated. In theory, it shouldnt
block flow at WOT, but thats theory...Its hard to machine a really effective
venturi in that short a space. Sooo... remove the ridges and you will get a
larger air flow rate at WOT (+25% more or less) and a much faster off idle
response. Make sure to radius the inlet of the bores as much as possible!
Removing some of the shaft diameter by flattening it with a grinder is good,
but leave the teflon coating on it at the central bushing/bearing. Try
painting it with a thin layer of a good etching primer to keep it from
rusting. Make sure you block off the bearing bores to keep stuff from
getting in the bearings during the whoel procedure. Also, its not the
surface finish that gets the flow rate. As long as there are no "chunks"
(+.008" high = chunk) the flow rate should not improve very much with mirror
like polishing. Looks nice though...
Bruce
----- Original Message -----
From: Bernd D. Ratsch <bernd@texas.net>
To: <dakota-truck@buffnet.net>
Sent: Wednesday, January 17, 2001 8:23 AM
Subject: RE: DML: RE: TB modifications
>
> Liability.
>
> One word of caution...if you've never done any porting work...don't try to
> modify the TB by yourself. All it takes is one slip with the
grinder/dremel
> to really screw up the bores. If you can, take the TB to a local machine
> shop and have them do the milling/grinding for you.
>
> (I do have experience porting/modifying carbs and heads so please be
careful
> with the hand grinders on your TB's...one slip and $100+ later for a new
TB)
>
> - Bernd
>
> -----Original Message-----
> From: owner-dakota-truck@buffnet.net
> Subject: Re: DML: RE: TB modifications
>
> So I have a question... If smoothing out the throttle body makes such a
> good difference, how come they don't come that way out of the factory? I
> can understand it being too expensive to produce them with an ultra smooth
> finish, but couldn't they make 'em closer to what we're doing to them?
What
> are those ridges supposed to do anyway? Someone said they are
> over-engineered... For strength I assume? Or for sound baffling? More
> like Tod baffling...I can't figure it out. Is there some risk in taking
> them out?
>
> Anyway, this mod sounds like something I want to try.
>
> This list sure is expensive... I wasn't planning on doing any mods. Now
I
> have a growing list of them...and I don't even *have* a Dakota yet!
Twenty
> days since my order...and counting.... -Tod
>
>
This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 11:58:36 EDT