Frank, YOU DA MAN! If you didn't live so far away
I would be over every day with a thousand questions
and just to hang out. And I know I"d have the fastest
truck on the DML. Bet your glad you live in Cali now
huh?...hehe.
GS -
Frank.T.Holloway@KP.ORG wrote:
Good questions, let me see if I can answer them and put some of the
other questions and statements to rest.
First, anyone that says they have the best TB for all situations is
either driven by greed or is smoking
something. The simple truth is that there is no one solution that will
handle all possible variables that you can
throw at these vehicles. They are no different than cams and can be
mis-matched just as easy. You wouldn't
select a cam that has duration figures that generate a powerband from
say 4,000 - 8,000 unless you had
something really special (weird) in mind. The TB's are the same. Dodge
actually did a fine job with these given
the goals that they had in mind. The engines are powerful and develop
their power down low, offer decent fuel
mileage and are emissions friendly. The variable venturi (the
restriction above the plates) was placed there for a
purpose and actually makes the machine operations from the factory more
complex. The restriction is placed
there to make the vehicles more docile off idle by shrouding the half of
the throttle plates that swing upward.
This i!
!
s all part of the power and emissions equation. Almost every change made
can have both positive and negative
results. What seems generally positive to some can be viewed by others
as obnoxious or down right
unacceptable. Removing the shroud above the plates with no other changes
will make the engines more jumpy
just off idle. Some like this and others don't. The other area that
everyone seems to be making a big deal about
is machine work. Honest truth, todays CNC machines are capable of
repeatability down to .0002 inch (a heck of
a lot better than the days where we cranked knobs). Putting down one's
machine work without knowing how
they are performing their work is just plane stupid. We send out our
throttle shafts to have them centerless
ground and they come back from the grinder with tolerances of plus or
minus .0002 inch (way better then you
actually need). Some have commented on attach methodology, whether the
plates are attached with countersunk
cap screws, buttonheads, w!
!
elded in place, staked in place, the list goes on and on. It really
doesn't matter as long as the plates don't come
loose. The bottom line is all of this is really moot. What is important
is the flow numbers and how our trucks
react to the changes. We have tried almost all possible combinations and
feel we have arrived at a change that
best addresses our goals and just as I says this, I am sure that others
have made changes different from ours that
make power in different areas. There is nothing magical here, just
testing and verification. The work that we
perform on these for our Stage I's is more complex then just punching
out the bores to a larger diameter, but we
know it works and increases power throughout the entire powerband. The
work on the TB is as follows, first
we locate the TB bore centerlines. We do this with a contact probe in
the CNC, four points are touched in each
bore and the centerline is calculated. This could be actually performed
with a dial indicator. On!
!
ce centerlines are known, then the TB is bored (variable venturi is
removed) and final diameter is set at .015 inch
smaller than the throttle body bores themselves. The boring head is then
moved .007 inch towards the back of
the throttle body and bored again. In essence, what this does is leaves
a partial shroud for the plate halves that
swing upward. Once complete, we then remove the air horns that rise
above the top of the TB. We do this on
the CNC and leave four tabs for the gasket. The next step is to machine
the air compression angle. This is
performed with a carbide end mill. The angle is 7 degrees and actually
starts .050 inch above the plates and
continues all of the way to the top of the TB. Two words of caution, you
don't want to start this angle any lower
than .050 above the plates and you don't want to intersect the holes at
the top of the TB where the hold down
bolts go through because you will allow unfiltered air to enter the TB.
In regards to the throttle shaft!
!
s, we make new ones. We chose this route for two reasons, we didn't want
to work with the factory one
because of the half shaft approach that we use, re-working the factory
would be a compromise and take too
much time, the second reason is that stainless steel wont rust. We
re-use the factory plates but we do tumble
debur them and ship them out to be anodized. Some people have commented
on the lousy machine work out of
Dodge in these, let me put this to rest. The factory plates are stamped
and tolerance on these are accurate to
within .001 inch. Bore centerlines have been accurate to within .004
inch and bore diameters have been accurate
to .002 inch. The bottom line on the above work is an increase in flow
of approx. 100 cfm and no loss in
velocity through the TB. I hope the above info helps, any other
questions, send a post.........
Frank
---------------------- Forwarded by Frank T Holloway/CA/KAIPERM on
12/13/99 08:03 AM
---------------------------
Mtbfed@aol.com on 12/11/99 09:38:00 PM
To: dakota-truck@buffnet.net@Internet
cc: (bcc: Frank T Holloway/CA/KAIPERM)
Subject: DML: Re: Re:Best throttle bodies?
Well Frank, first off thank you for this info. Now, seeing that the
stock
manifold flows around 650 CFM, and a worked over
stock plate TB will flow about the same, how much work are we looking
at? Is
this as easy as maintaining the lower bore
diameter up to the top, or is that 670 CFM reached by a thinner shaft,
countersunk bolts, and tapered bores...etc.
The reason I ask is that I have access to a shop that bores motorcycle
carbs.
What do you guys do to the $90 TB's
BTW, where are you located?
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