TB porting tips? +big warning!!!

[John_D.]

Well, I decided to look at my filter after running the free ram air for a while. Sure enough I have a dirty strip where the opening is, so it must be pulling some good air up through there.

Then I decided to cut the divider strip from the outlet of my lid while I had it off. Then I decided to take the silencer off and try some dryer vent hose, just for the heck of it. While all that was off, I decided to take the maf screen off and straighten a couple of the openings where I had scuffed it about a month ago. Then of all things, I decided to take the tb off and examine it. Well, guess what, while I had it off, I decided to cut the post out of it... I mean, I was there, it was there, you know how it goes. ;)

So, now I have this sawed up tb laying on the bench, it's going on 10:30pm and I have to drive the old clunker truck tomorrow. That'll teach me to check my air filter!

Any tips on finishing the job? :eek:

My dremel quit working last weekend, so I guess I need to get another one to do the cleanup work left over from where I could only get so close with the hacksaw.

Is "polishing" really needed, and what grit(s) sandpaper should I plan to progress through? How much cleanup work should I plan on after the dremel work, even if I don't "polish" it?

Do the typical parts stores carry the tb gasket, or will I have to make a run to the dealership, or worse yet, special order it...?

How far off will the maf be, just for reference? I have the maft and autotap, so I will be adjusting the maf after I get it running, just looking for a sanity check on the delta. (ummm, Magnus, do I dare ask if the initial change should be on the base or the wot dial to get a good idle?!) ;)

How did everyone else ensure they got all the metail filings and dust out of every nook and cranny when done? I was going to take the throttle blade shaft out, but it didn't seem very willing, so I left it in there. I don't think aluminum filings in the bushings will be very good for it though. :(

And what's up with putting that little tit in the middle of the star opening on all the electronic attaching screws, so that my star bit won't fit in the hole... Pliers still work on them though! So, there, HAH, GM!

Anything obvious I am forgetting about doing this right and getting it back together right...?

(and yes, I did the dreaded search in case some helpful person was thinking of mentioning that... Do you know if you do a search on TB and Port, you get 320 hits... It's cute how STB matches TB...)


edit - I just realized this probably goes in intake/exhaust, as I was getting ready to shut 'er down for the night. But, at the same time, I also remember Magnus saying something in another post about not even looking in that forum anymore too, with all the repeated exhaust questions, so maybe if he can look at this question first before it gets moved...?!

[ June 06, 2002: Message edited by: John_D. ]

[ June 08, 2002: Message edited by: John_D. ]

[ June 08, 2002: Message edited by: John_D. ]</p>

[MidLifeSpeed]

You really should polish it some, if nothing else, just to smooth out where you were chopping on the post. Don't forget to COMPLETELY remove the MAF metering plate (behind the MAF assy, held on by two screws) or you will be running so lean (w/o the MAFT+) that you won't be able to drive it.

I used dremel polishing cones (little abrasive cones on a post) of different grits to polish mine, and had no problem.

I was also able to get a TB gasket from O'Reilly, but they had to order it for me (had it next day).

Those funky screws are "security torx" screws, meant for us "laymen" to stay away from ... :D
... however, like you said, pliers will work after using the edge of a pair of wire cutters to break them loose. (After doing all this, I found my security torx bit set ... :rolleyes: )

[Magnus]

This seems like a more advanced tech topic anyway.. I'll leave it here for now.

Pliers on the screws yes. [img]smile.gif[/img]

Dremel is needed to finish the job too.. Mine was a variable 5 speed but now all speeds are 5. :(

How much of the post are you removing? I only removed the bottom half of mine but I may go an remove the top half as well.. and as previousely stated, that rear bronze backing plate HAS to be removed.

WHen your polishing it up, I'd just grind it down smooth, and then use the dremel polishing compound with the soft tips they have.

As for the MAFT+.. I'd STILL leave the base at zero. You will run very rich on a cold start and the idle will search, but your MAF readings will be 100% precise when it comes to fine tuning the beast at WOT. [img]smile.gif[/img]

You may have to lean it out a little on the WOT end though.. -2 or -4%. Use autotap to verify.

Also, don't torque the TB down TOO tight.. espeicaly the lower bolt.. I broke that bolt inside the upper intake once.. it was NOT pretty..

Oh yea, to clean the TB I just ran water all throughout it.. made sure it was VERY clean.

- Keith

[John_D.]

hmm... how much of the post... I only did the bottom half so far. Hadn't even thought about doing the top half. Need to think about that one some more.

Seems like those little maf wires would be very exposed, but so what, nothing is going to be in there around them anyway, unless my maf screen disintegrates or something... The top half of the post won't stop small stuff from getting to the wires anyway. Man, I wish you hadn't asked that, I'm probably going to go cut it out too now! I'll end up being the guinea pig on that.

There is a little bit of a funnel to the top half of the post, so removing all the post would eliminate that funnel, so it will probably throw the readings off even further, since less air would hit the wires.

At the very least I will work the back side of the top half. Like where the top screw goes, it sticks out into the airflow. Make the back side the same size or smaller than the front (more aerodynamic...)

And maybe smooth off the ridge where the opening narrows in the tb.

Time to go hunt up a gasket and a new dremel, and start calling around...

[Magnus]

99+ TB's MAF sensor just hangs down all open.

I might remove my upper half as well.

Yea, it does kinda funnel air.. Wonder how much it would actually change by removing the post though.. perhaps it will pick up more air due to less obstructions.

PS. You certainly are making good use of Advanced Tech. ;)

[John_D.]

Well, I did it. Went home at lunch and cut the top half of the post out too. Man, it looks so much better. I went back and looked at http://www.carolinafbodyclub.com/iro...rted-f_jpg.htm and if you think that looks good, just imagine that top post gone plus all that excess at the top, above the post.

Now all I have to do is a little bit of clean-up work in there. (ha, little bit, yeah right...)
:(

Dealership had the gasket for $6, not bad. [img]smile.gif[/img] None of the parts places around here (Advance, Autozone) can even get it.

I'll keep you all posted on how it runs (idle and wot), and what I get reported back from autotap and maft tinkering. I'm wondering what the new flow rates will be...?

[John_D.]

If you take the upper half of the post out, DO NOT try to remove all the material in the front to be even with the rest of the throttle body.

You WILL penetrate to the outside, on the two front corners where the post once was attached. And this is still with 1/8" or more to go, to reach the tb inner diameter.

The penetration points, looking from the outside, are at the base of the maf sensor mounting, on the outside edges, right up next to the ridge at the opening of the tb.
:eek: [img]graemlins/crybaby.gif[/img] :eek: [img]graemlins/crybaby.gif[/img] :eek:

I'll try to get a picture later, though I don't have a place to post it. (after I go find some jb weld or something to try to patch this up...)

I'll probably fill the corners on the outside, the corner of the maf sensor ridge and the air intake ridge, letting some of the patch mushroom into the inside. I think holding a seal under vacuum won't be too bad, because I can gob the sealer into the corner from the outside, and there is no way it is going to get sucked in. But holding a seal under boost has me worried. Hopefully I can get a little mushroom/rivet-like bit of the patch inside, so it can't be blown out either. Although it will be sticking into my freshly ported/smoothed/polished tb insides...

The other thought is rtv sealer. Haven't decided yet.

[Magnus]

Damn.. Real sorry to hear that.

E-mail the pics to me at magnus_dx@hotmail.com.. I'll host them for you. Please take as many as possible for future referance.

You could call up some junkyards or places like speedautomotive and see if they have any.. or possibly post in the for sale section.. I know several people buy complete 3.8 motors that come with a TB... so they might have a spare they are willing to part with.

I would not trust it under boost.

[John_D.]

Good point about extras floating around. I'll check and see what I can find. In the meantime, to get this thing running again, I'm gonna patch 'er up and go on with it for now. That will buy me some time to find one and start porting all over again...

Do you know if anyone has compared the mounting surface of the 99+ to the '98? I know there is the by-wire vs. cable aspect to consider, but that might be swappable. But if the mounting surface is different, then it's definitely out.

hmmm, also if the wire vs. cable is swappable, then I could go with the whole intake manifold and the tb, and not have the angled tb anymore.

Well, off to Advance for some jb weld...

[Magnus]

I'm pretty sure the bolt hole locations differ on the 99+ vs the 98-.

Also, to convert to a electronic TB, you have to switch PCM and the throttle pedal setup.

[John_D.]

I was talking about taking my 98 throttle cable rotating assembly and attaching it to the 99+ throttle shaft, if it's the same diameter shaft, with the same 2 flats. The only other problem area would be the mounting holes for the throttle cable bracket. If that would work, then all my cable, pedal, etc would still be in place.

Got some pictures on the new camera I bought while I was out... Just sent them to you, they bounced, too big, I'm cropping them now... Ok, that's done, sending them now.

Well, they bounced too, message said you've exceeded your storage limit... The email is 900K. Let me know when I should resend. [img]smile.gif[/img]

[ June 08, 2002: Message edited by: John_D. ]

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[John_D.]

It's all back together, and it even runs too!!

I did not put the dryer vent on. Discovered it has pinholes throughout. Plus it just doesn't look too hot...

Can't tell yet, exactly what difference the p&p makes. Feels stronger in the middle, and about the same on top end. I need to get it to the track. (oh yeh, I ordered the nos5175 kit last night too, so that will be another factor at the track next time...)

It hunted at idle in the beginning. I had been running the maft at -10 base, +0 wot, and left it there for the initial start. Reset it to +0 base, +0 wot. Idled better. Drove it around a while, and it got even better. But, I was getting .95 o2's at wot. So I reset the base to -5, left wot at +0.

After logging for a few miles, found that the averages look really good, and I hit all of my targets dead on. Cruise lt's were -2. wot o2 was .88, kr was minimal (same as before the p&p).

But I also found that the wot o2 varies by speed, so the average does not tell the whole story. It was good around 40-60mph (in the .88-.90 range). The faster I got, the more it leaned out. I think this is what magnus has been trying to tell me about getting "consistent" o2 readings. At 90 it dropped into the .82-.85 range. I don't know if it did this before the p&p or not...

So the next step will be to go back to the zero setting on the base, and see where that puts the o2's at various points across the mph band. If they are more consistent, then I can tweak them with the wot setting after all... (yes, I believe it must be that non-linear maf response you wrote about in another post, sir magnus!)

[John_D.]

Ok, here are the results from setting the maft back to zero....

The maf sensor must have been designed to work in an open air setting, because it is dead on now. .90/.89 wot o2. It leans out just a little from 90-112 in 3rd, about .88/.87, then goes back to .90 when it catches overdrive.

Hey, magnus, when you free up some space on that hotmail account of yours, let me know, and I'll send you those pictures.

[DominusEtDeusNatus]

Why don't you just post them?

[Magnus]

Dom, you cant just upload a pic to the message board, you have to host it on a website.

Also, call me.