Are you talking about grinding the mouth of the bores out bigger and blending/ polishing them?? That's bad? Just trying to understand cause I may have gone too far with mine?? Pics aren't the best but I think you see what I'm saying.

 

Don't you want the fuel cone to spray on the walls of the TBI bore? I thought you wanted it to hit the wall and run down. Then the air squeezing past the throttle plates atomizes the fuel at idle.

I read that in a PROM tuning article on why you want almost NO IAC counts at idle. Because the more air that goes thru the IAC the LESS the fuel is atomized because the air is bypassing the throttle plates.

 

you want the spray to hit ever so slightly above where the plates hit the bore, yes, so the fuel gets sucked through the gap.

astro, that looks sweet. thats exactly how everybody should model doing theirs. dont tell me you did that with a dremel!!
If i had an air grinder i would have radiused the edges more, and polished the whole thing to mirror.

 

:hail: Mighty Dremel !

 

I'm working on one right now that has sealed roller bearings on the throttle shaft. The bearings are set into the body of the TB and epoxied in place so the throttle shaft will spin, not the bearing. You should see the radius on this one! ALL done with the disc grinder and HAND FILES

I think me and Astro4x4 have a friendly competition to see who can make the most rediculous radius on a TBI

 

and what do you need roller bears in a tbi for? overkill?

lets see pics as soon as you got em.

 

Well, we figured that sealed (that's what I'm using) bearings would do two things.
1. Eliminate any chance of air getting past the cheap crappy felt seals G.M. used. Maybe only minor but the more air mixing with fuel the better, I say.
2. Eliminate throttle shaft binding as the aluminum wears and egg shapes, as my currently running TB has done.

It's also a durability thing, I don't want to tear this one down again for a long time. I also hope it will take some boost in the not to distant future.

 

blending/radiusing edges/polishing them is the ticket! Elimeinates as much of the turbulence as possible... Man, that tb is so friggin shiny! I love it... how long did it take you to do that? :hail:

 

A couple of hours max, on the bores and about an hour playing with the injector pod.

 

anybody measure or figure out injector cone spray angle yet?

 

I just baught an Injector Spacer for my TBI. It costed 19.99 from Jeg's its amde from Heat resistant ABS plastic it raises the injector about 1/8" more than the gasket does. with the gasket its 1/8" over the Blades and the spacer makes it 1/4". I rebuilt my throttle body (injector pod) while i was in the process but i had a minor problem with getting the fuel lines to go in properly. I noticed a bit of performance difference bbut maybe thats b/c I hadnt been bangin the gears for a whole week. but this is a very good topic. And all of this information will be benneficial to anyone who reads it even if they have a TPI. A good TBI site is http://www.goingfaster.com/spo/tbi.html
they have all the specs and performance mods for it "mostly" for a 305 TBI motor.

 

ya

On the return spring side of the throttle shaft, you have mill down the...umm...guide (?) that the spring goes around so you can cut a good seat out for the bearing. BUT that will allow the throttle shaft to "float" slightly. The throttle plates will probably stop that but it might end up making funny wear patterns. Sooo (here's where my "Missouri-ness" shows) I took a spent shell casing from a 10mm handgun round and cut it down so it acts like a spacer. It presses on the bearing on one side and the end of the throttle shaft on the other.

I epoxied the bearings in place so they don't leak, and so they don't spin in the bore.

http://communities.msn.com/V8AstroCa...to&PhotoID=126

http://communities.msn.com/V8AstroCa...to&PhotoID=127

http://communities.msn.com/V8AstroCa...to&PhotoID=128

http://communities.msn.com/V8AstroCa...to&PhotoID=129

 

ausome photos, i think i saved all of them to my HD. Anyway, i like the idea, but i was given a pretty good one that would be cheaper and replaceable. Plastic Grommets, They make all sizes you could ever need. You would just machine out a recess for em, and put em in so that they are a little tight on the throttle shaft, and when they wear down you pop em out and push in some new ones. This will help the wear on the aluminum. But ive got a tbi thats been on the car for 120k and the shaft still fits tight in the tb.

o and thanks for the info, i will see if my cones in cad need reworked.

 

i can do the ultimate TBI mods for any of you for $40 plus shipping which is about $50 total. ask 91bird305 or his sn j007golden about the bad *** job i did on his

camaroracer1992@yahoo.com or camaroracer1992 on AOLIM

 

Hey Capt, that TBI is different than mine, but then again mine are both truck TBIs. I have return springs on both sides and that was the reason for the "thin section" bearings I had to get. Looks like you have it alot easier than what mine is turning out to be.

 

Return springs on both sides?? I dunno...all the TBI's I've worked on were from Astros. I have the small, round TPS opposed to the earlier flat TPS. Doh!

Are the truck TBI's setup to have the throttle cable bracket bolted to the side?

 

its just the tps difference, and springs on both sides if you ask me is a better idea, but... not needed though.

i just finished doing some mega grinding on my 454 tbi, mwahahaha. im evil arent i. and then gave about a .5" radius to my sb tb.

ill post pics later.

 

ok radius is better than fillet.

its on the car, definate gain in high rpm power, and definately easier to rev to 5k where it used to die at 4500 and therefor shift. now it keeps pulling all the way up

 

Hell yeah, Camaroracer1992 did an awesome job on my TBI. I recommend him to anyone.

 

Snuf - how did you come up with those TBI graphics? They look like CADKEY 98 stuff that I've been using at school. Most cool.

TP

 

they are autocad 2002i solids that i have plotted by measuring out actual components. I did this after i redesigned the tbi unit that im still dreaming of producing.

 

Awesome - My junior year I dismensioned out an aluminum C-rod and did that as my final project. coolness

TP

 

im a speech major. (organizational Communications) about 30 credits away from being done. as well as a business major (finance and banking = double major) about 45 more credits away

above = 3 majors, 2 degrees

ive learned cad on my own, and suprised a few engineering students and teachers. I would take a few engineering classes but i dont have time. I might get a bachelor or science in mech engineering after i finish these 2 degrees. along with teach some communication classes

then someday i would like to get a masters.

but I will always be an engineer at heart. :lala: <- happy cloud engineer.

 

what are you guys seeing for 1/4 mile times after doing these tbi mods?? Is it that much of a power increase?

 

Well im guessing about at least 50 or even 80 cfm increase



But not sure.

As for 1/4 again, i would guess a tenth or maybe a bit more with more mods. Since this would be one of those things thats increased power by a percentage of what you already had.

Those are my guesses

 

What Dremel bits do I need to do the work, including the polishing? I'm looking to pick up some above-4200rpm performance and this might help me out.

Thanks

 

its a drum that looks like a saw blade and its metal. it will take that ridges right down fast.. be careful not to take off too much, then after you get it down ok, use the coarse, then finer sanding drums.

again it looks like a saw blade, a really thick saw blade, a tubular saw blade.

 

Ok, I'll poke around Home Depot and pick up the thing that best resembles that bit...I will also pick up new sanding drums in a wide variety. What should I use for the final finish, after I'm done with a fine grain sanding drum?

 

Can someone fix the links to the pics. I can't see any of them. All I get is red x's. Thanks.

 

Yeah snuf if you could fix the links to the pics in this thread that'd be great. This was a really good post with a lot of good info. I think that some of these TOTW posts were really informative. I'd suggest making some kind of sticky that points all newbies to a link with a search on all the TOTW threads and get them to read all of them first before posting questions, many posts would not be repeated so often that way I believe.

 

How thin are you guys shaving the throttle shaft?

 

i did mine 2-3 mm just guess you know whats right.

 

this mite help

http://images.google.com/imgres?imgu...8%26safe%3Doff

 

GO HERE FOR A LOT OF MY TBI RELATED PICS.

HTTP://SNFLUPIGUS.TRIPOD.COM

CLICK PHOTOS. THEN TBI RELATED PHOTOS. THERE YOU ARE

IF YOU HAVE MORE TBI RELATED PHOTOS. SEND THEM TO ME PLEASE. EMAIL SNFLUPIGUS@***.NET

IF YOU HAVE SPECIFIC REQUESTS EMAIL ME.

NIC

 

the bit i used. about 14 bucks works like a charm at any speed on alum. i wore it down a bit grinding on my steel computer case recently. not a good idea. ran out of cutting wheels. should have waited.

 

Call it luck but i wound up with a larger bore TBI on my 305, its not the standard 1 11/16" much closer to 1 25/32 -1.78125" and this is a stock TBI.