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I've seen some horrible Dremel jobs and I'm sure they have scared off some from doing it themselves. Awhile back I acquired one of these hacked TB's with a bunch of other parts. Sometime afterwards I looked at it and thought how could it have been done better.

The best tool that I found to open up the bore is a two inch flapper wheel. Shaping the radius was done with a combination of a mandrel mounted abrasive and a three inch shaped flapper wheel. The two inch flapper is the perfect diameter for opening the bores and eliminating the step.

Start by removing the throttle shaft. You can achieve a taper by working tool up and down taking a few extra strokes near the top. Be careful and do not allow the tool to go below the holes for the throttle shaft.

The radius is somewhat more difficult but I got good results by being creative. I made a simple rotary table of sorts by nailing a short 2x4 to a bench or you can nail it just about anything, kitchen table, patio post, etc. :joke: :jester:

This is where a friend would come in handy but I managed to do it by myself. Fasten the tb to the 2x4 with wood screws with the bore centered over the pivot point (nail.) Take the mandrel mounted abrasive and roughly shape the radius on both bores. After you have done that take the three inch flapper wheel and use a file or grinding wheel with the flapper wheel turning to shape the desired radius on the bottom. Then use the wheel to true up the radius.

The flapper wheels and other abrasives are available in various grits. Since most of the metal was already removed on my project I only used 120 grit to rough and finish the bore. The radius was done with an 80 grit but it took a lot of work to polish out the scratches.

Now I don't usually polish the TB when I machine them because I have seen no measurable difference. Let me just say that there is evidence out there that suggests texture surfaces can actually increase laminar flow. The important thing is have a smooth consistant profile. An irregular surface, even if polished to mirror finish will not flow as well as a smooth uniform 80 grit finish.

On this particular project the surface, the remaining two ears and boss for the airhat screw were ground off using a two inch disk in a right-angle grinder. Just before the final polish the entire TB was bead blasted. If you decide to grind off the boss for the airhat screw you will have to drill and tap it deeper and make an S-bolt. It's a little extra work and achieve little or nothing but it makes for a neater job.

Start- Hacked TB



The Tools-



The Process -



The Finished Product -

 

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G.F.Y racing president
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that 2 inch flapper sanding wheels does a nice job for the tb bore holes on the intake too. did mine on my dak a little while ago.. :banana2:
 

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Discussion Starter #4
realdeal7369 said:
that 2 inch flapper sanding wheels does a nice job for the tb bore holes on the intake too. did mine on my dak a little while ago.. :banana2:
That's the only one I'll ever do by hand again. Way too much work to get it that good. I just had to see if I could do it. I knew there had to be a better way than using a dremel type tool and router type tools.
 

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What is the completed diameter of the ports? (i.e. 50mm, 52mm). I would imagine the throttle plates no longer match up to the port size as well - is this a problem? Also, why not just taper the airhats?

Thanks for the info,
2000DakotaQC
 

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Wow, the finished product looks A+++++++. :biggthump Great work man! I wanna try this myself.
 

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DakotaQC2000 said:
What is the completed diameter of the ports? (i.e. 50mm, 52mm). I would imagine the throttle plates no longer match up to the port size as well - is this a problem? Also, why not just taper the airhats?

Thanks for the info,
2000DakotaQC
the plates should fit just fine seeing as that he made a note not to go past that point in the bore
 

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That Guy
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All that does is turn it into a true 50mm by removing the step inside the bore. Doing so will give it an increase in airflow which equals power.

Here is the first TB I bored out. Too big for my V6 but it makes a nice paper weight :jester:

 

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Very impressive! I always used a port & polish kit designed for doing heads with my die grinder, but I'm going to have to look into those flapper sanding wheels!

What size do you think I'd need to do a 4.7L throttle body?

There shouldn't need to be much of a radius shaped into the inlet on a 4.7 TB, but I'd definitely like to play around with a couple.

This looks like the beginning of a fun project!

One last thing...How fast do those flapper sanders remove material, and how long do they last? Will one do a complete TB, or should I get a spare?
 

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I would get 2 of them cause they seem to wear down fast or at least they did for me
 

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In the immortal words of Bo and Luke Duke...YEEEE HAAAAAAAAA!!!!!!!

Just came back from the shop where I ported my first 4.7 throttle body. Wow! What a difference!

I did the flapper sanding wheel trick with a drill, and finished it up with some fine buffing compound on a cloth buffing wheel that I had laying around that was the perfect size to fit the bore. I proabably wouldn't have gone so radical had I not found this sitting there doing nothing. Finished up with a little hand polish with some Nevr-Dull, and put it back together.

I also removed the little plastic "dimple" from the top of the intake manifold where the TB mates up to it. I just scored both sides with a razor knife, and twisted it off with a needle-nose pliers. Not sure if it'll do anything or not, but it looked like it was in the way of smooth airflow, so off it came.

Took it out for its initial road test (after finishing up my temper tantrum when I dropped one of the air silencer screws way down between the plenum and the head) and at first it seemed unimpressive. I couldn't really tell any difference in throttle response while cruising, though I did notice it being a little "crisper" when putting around the parking lot at the shop. Took it out on a back country road and planted my right foot, and it bogged and sagged miserably before it started to come alive. I guess I should have disconnected the battery so the PCM could re-learn. Once its initial fit was over, it started to pull like a freight train! I never realized how smooth a 4600# vehicle could be at 110 MPH! All the way home I couldn't stop kicking it down to 2nd (or is it 3rd, or 2nd Alt.?) at 60 MPH just to let it wind out to ~85 MPH and upshift, only to slow down, cruise a little, then do it again!

The more I drove it, the better it got. I've had the "air bog" before when I did TBs on 5.2s so it didn't make me too nervous. It just takes some time to learn the new amount of air that it's inhaling.

I'm certainly not going to get any MPG on this tank!
 

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Mopar Mike said:
In the immortal words of Bo and Luke Duke...YEEEE HAAAAAAAAA!!!!!!!

Just came back from the shop where I ported my first 4.7 throttle body. Wow! What a difference!
I did the flapper sanding wheel trick with a drill, and finished it up with some fine buffing compound on a cloth buffing wheel that I had laying around that was the perfect size to fit the bore. I proabably wouldn't have gone so radical had I not found this sitting there doing nothing. Finished up with a little hand polish with some Nevr-Dull, and put it back together.
I also removed the little plastic "dimple" from the top of the intake manifold where the TB mates up to it. I just scored both sides with a razor knife, and twisted it off with a needle-nose pliers. Not sure if it'll do anything or not, but it looked like it was in the way of smooth airflow, so off it came.

Took it out for its initial road test (after finishing up my temper tantrum when I dropped one of the air silencer screws way down between the plenum and the head) and at first it seemed unimpressive. I couldn't really tell any difference in throttle response while cruising, though I did notice it being a little "crisper" when putting around the parking lot at the shop. Took it out on a back country road and planted my right foot, and it bogged and sagged miserably before it started to come alive. I guess I should have disconnected the battery so the PCM could re-learn. Once its initial fit was over, it started to pull like a freight train! I never realized how smooth a 4600# vehicle could be at 110 MPH! All the way home I couldn't stop kicking it down to 2nd (or is it 3rd, or 2nd Alt.?) at 60 MPH just to let it wind out to ~85 MPH and upshift, only to slow down, cruise a little, then do it again!

The more I drove it, the better it got. I've had the "air bog" before when I did TBs on 5.2s so it didn't make me too nervous. It just takes some time to learn the new amount of air that it's inhaling.
I'm certainly not going to get any MPG on this tank!
deffinately reset the computer. once things are disconnected, the computer throws a fit. also...

:needpix:
 

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blue2000sport said:
All that does is turn it into a true 50mm by removing the step inside the bore. Doing so will give it an increase in airflow which equals power.

Here is the first TB I bored out. Too big for my V6 but it makes a nice paper weight :jester:

nice damn tb man!... sweet :biggthump
 

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As much as I like my ported TB, I'm going back to a stock one. The performance gains were impressive, but for the basic commuting that I do, it's a little too touchy. I see now why they have that ridge in the upper bore...It allows the throttle to be more "progressive" at light openings, and by removing this, it now becomes more of a "hair trigger" feeling when just driving lightly around town.

I'll probably keep it around just for the sake of saying I did it, or maybe put it on my dad's Dakota sometime and scare the crap out of him the first time he floors it! :drive: :biggthump
 

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Mopar Mike said:
In the immortal words of Bo and Luke Duke...YEEEE HAAAAAAAAA!!!!!!!

Just came back from the shop where I ported my first 4.7 throttle body. Wow! What a difference!
...
All the way home I couldn't stop kicking it down to 2nd (or is it 3rd, or 2nd Alt.?) at 60 MPH just to let it wind out to ~85 MPH and upshift, only to slow down, cruise a little, then do it again!
There has to be a name for this affliction. I have the same "problem". It pulls SOOO strong from 60-90 that it feels twice as strong as it actually is. Really fun stuff! It pulls really strong at lower speeds with the OD off.

And I haven't noticed any tip-in. The thottle is pretty controllable. This is not to say that I don't find myself generally running at either idle or WOT, but it is through no fault of the TB ;)
 

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just wondering if this would work good on a 3.9 V6. Don't want to start ripping things apart and doing modifications then ending up not being able to use my truck untill I order in a new TB.

Thanks
Chris
 

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Discussion Starter #17
Katalyst said:
just wondering if this would work good on a 3.9 V6. Don't want to start ripping things apart and doing modifications then ending up not being able to use my truck untill I order in a new TB.

Thanks
Chris
Works the same way. This wasn't written as encouragement to do it but advice on how to do it better. If you don't have faith in your ability to do the job then it is best not to start it.
 

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Off topic.

N56629 - I like you OTHER Dakota! I have flown a bunch of Warriors and Arrows, that is a nice one you have.
 

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Discussion Starter #19
Thanks, it just had a new paint job. I would like to get rid of the Hersey bar wing tips but don't want to give up the fuel. 82 gals. lets me go a long ways.
 

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N56629 said:
Works the same way. This wasn't written as encouragement to do it but advice on how to do it better. If you don't have faith in your ability to do the job then it is best not to start it.
Understood. I do all the modifications to my truck so everything I do is a risk.....plus the only way to really learn. Ordering in a new TB to try it on first so we'll see what happens. Thanks for the info.

Chris
 
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