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Unread 10-28-2007, 12:52 PM   #1
lost honda pro
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Bored my throttle body *pics*

So, I've read about people doing this, and after checking out how ridiculous the lip is inside the stock TB, I decided to get it bored by a shop.... but he wanted $50 to do it, and I'm cheap as hell, and Harbor Freight was running a sale...

So I bought a $44, 5-speed, 2" stroke bench drill press, a $12 60mm hole saw bit (that didn't end up working), a $4 1.5" sanding drum (50 grit), and a $3 pack of 120 grit finishing drums. (total of $51, if you negate the $12 hole saw that didn't work, more on that later)

So I started with this stock TB off the spare '99 motor I have.





First step is to remove all the sensors ( T20 Torx bit ). The IACV has four bolts, the MAP has 2 bolts, and the TPS has two bolts. Don't hesitate to just yank em off, there are no adjustments so you can't FUBAR it.

Next you remove the two T20 bolts holding the butterfly on. (You must hold the butterfly 100% open in order to slide it out.) Then you slide the spring/bar assembly out.

I used the stock TB gasket to draw a centered circle around on the BOTTOM of the TB, where I bored it out. Then just move your drill press table up to the proper height, and work your way around. I stopped pretty frequently to A) let it cool, because Al gets hot pretty quick, and B) to make sure I wasn't removing any material past the lip, because the butterfly is only 60mm, and once you make it to big, you have to get a new butterfly made.

Once I got enough material off, I switched to the 120 grit drum and smoothed it out. Then clean it up, and re-install all the sensors and whatnot.

NOTE: I didn't take any pics because this is a pretty simple procedure, and there are plenty of other write-ups if you need to see pics.

As for the hole saw bit: I thought this would be a quick and painless way to bore the TB, but it turns out that commonly available hole saw bits were NOT made to bore perfect holes in metal. In wood, it obviously doesn't matter if the bit is 0.03" out of round, but for metal, it doesn't work. I tried to go down from the top, where the TB tapers down to 60mm, but ended up scoring it pretty bad (you can see it in the top pic really well ). It definitely took more time, but instead of paying $50 for someone else to do it, I spend $51 and have a drill press too

Final pics:





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Unread 10-28-2007, 01:08 PM   #2
4.0H.O.XJ
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Looks good! ......WAAAAAY Better than mine turned out.

Mine looks like a beaver chewed it. No wait......the I.D. of my throttle body looks like something from the special education pottery class.

Yeah well, it flows better. Yours looks GREAT. Wish I'd done THAT instead of trying to use a die grinder and a flapper wheel.
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Unread 10-28-2007, 01:44 PM   #3
lost honda pro
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Quote:
Originally Posted by 4.0H.O.XJ
Looks good! ......WAAAAAY Better than mine turned out.

Mine looks like a beaver chewed it. No wait......the I.D. of my throttle body looks like something from the special education pottery class.

Yeah well, it flows better. Yours looks GREAT. Wish I'd done THAT instead of trying to use a die grinder and a flapper wheel.
lmao! dude you see that first pic? that torn up rim about 0.5" from the top? yea. tore it the hell up. i'm still upset about that.

anyway, thanks for the comments, but i have to give credit where credit is due, and the drum-sander-on-the-drill-press was not my idea, i found it on a couple other home-bored TB pages. it did turn out pretty good tho...

RESULTS!:

it definitely pulls. not pulls harder, but pulls. i could never say my jeep pulled at all before, so now i can say, mid to high end, it has a little pull to it. which is nice, except i don't spend a lot of time above 2,500 RPM.

i also got a whistle... whether that's because i opened it up too much at the butterfly is anyone's guess, but i've read that radiusing the openings for the IACV and MAP can alleviate some of the whistle. but since i just got it back together, that will have to wait till next weekend.
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Unread 10-28-2007, 02:41 PM   #4
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I have been thinking about doing this myself. I wonder how a cylinder hone would work
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Unread 10-28-2007, 03:19 PM   #5
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Quote:
Originally Posted by Bowhunter46563
I have been thinking about doing this myself. I wonder how a cylinder hone would work
i think it'd take WAY too long. a cylinder hone is meant to remove minimal material, just enough to smooth the piston cylinder (or brake cylinder) walls. you will be removing almost a full 2mm of radius from the TB, and while the area is small to begin with, it gets above 0.5" when you get close to 60mm. also, the surface is not flat, and once the honing stones are not parallel to the axis of the bore, you may have trouble straightening it. but thats not to say you couldnt do it...
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Unread 10-28-2007, 06:25 PM   #6
4.0H.O.XJ
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Quote:
Originally Posted by Bowhunter46563
I have been thinking about doing this myself. I wonder how a cylinder hone would work
Though it might be the PERFECT way to finish it off. I would have smoothed mine with a stone cylinder hone if I'd thought about it.
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Unread 10-28-2007, 07:36 PM   #7
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I can't find that drill press that you have... what is the part number? I was thinking about buying one also.
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Unread 10-28-2007, 08:01 PM   #8
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Quote:
Originally Posted by 4.0H.O.XJ
Though it might be the PERFECT way to finish it off. I would have smoothed mine with a stone cylinder hone if I'd thought about it.
wow... i didnt even think of that... must still be feelin the effects of jax this w/e...

Quote:
Originally Posted by Goldenknob
I can't find that drill press that you have... what is the part number? I was thinking about buying one also.
Drill Press 38119 Link

it's Central Machinery # 38119. i called the closest store to me (45 mile drive) and they were running em sale ($44 w/ tax down from $70). so we made the trip, and stopped off at winghouse on the way back
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Unread 10-28-2007, 08:09 PM   #9
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how bout a ridge reamer and then a cyl hone?
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Unread 10-28-2007, 08:24 PM   #10
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if i were to get a spare TB, i would have to get certain years to match up with the certain manifolds right? Like, i can't use a one from a 99+ because the manifold on my 98 isnt the same?
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Unread 10-28-2007, 08:32 PM   #11
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Dont quote me for sure,

But I just swapped an intake from a 99 to my 96, and the throttle bodies were flippin' IDENTICAL on both.

I swapped my 96 TB onto the 99 intake and drove away like Mario Pimpdretti.
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Unread 10-28-2007, 09:56 PM   #12
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Quote:
Originally Posted by 4.0H.O.XJ
Dont quote me for sure,

But I just swapped an intake from a 99 to my 96, and the throttle bodies were flippin' IDENTICAL on both.

I swapped my 96 TB onto the 99 intake and drove away like Mario Pimpdretti.
TB's are the same, but electrical stuff & assoc. plugs may be different.

1: my '97 TB uses a different IACV plunger plug than the '99 TB i bored. but the actual valving for the two IACVs is the same, so i just pulled the plunger assembly off and switched em.

2: i know at some point in the early 90's they went from a firewall mounted MAP to a TB mounted MAP. im guessing it was '93?
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Unread 11-04-2007, 09:26 PM   #13
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So I had some issues with a cruise control vac line, and since it happened when I changed the TB's, I feared it might be a TB related problem, and switched back to the OE 56mm version.

The problem was a vac plug for the cruise came off, and the check valve on it leaks, so it was behaving like a TPS with a dead spot around 2100 RPM. I found and fixed the cruise problem, and figured since I had the bored TB off, and it whistled a bit, I might as well try radiusing the IACV/MAP ports a bit, to see if it helps....

Notes:
1) use Dremel to smooth the ports out
2) clean/dry the TB
3) grease the needle bearings
4) insert butterfly oriented as shown
5) no light showing through around butterfly
6) final assembly showing details

















I'm gonna install it after class tomorrow, I'll post results then....
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Unread 11-05-2007, 05:17 AM   #14
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As far as matching TBs, the 91-95 don't have the nipple for the MAP in the front of the TB.

The 96-01 does have the front nipple.

You can use a 96-01 on a 91-95, you just have to put a vac plug over the nipple. You cannot use a 91-95 on a 96-01 sinse it doesn't have the nipple.
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Unread 11-05-2007, 06:23 AM   #15
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thanks for straightening me out, balloo!
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