snflupigus

that slants the bores like the eddlbrock spacer, to compensate for the rear cylnders getting more fuel from it dripping off the blades there?

Thoughts, suggestions, ive had this idea of redesigning it and having a prototype machined, it really is a simple hunk of metal. all the complexity is in the injector pod.

Andy89RS

Don't forget about all the passages under and inside the TBI body. It is a little more complex than it looks from the top, but it shouldn't be too big of a problem for a good machinist.

Pablo

iTrader: (1)

ive thought about this too

first you want to ensure the injectors are spraying right at the edges of the throttle blades.. this wil ltake a spacer of the pod and some grinding so that the front of the spray cone is just getting past the front edge instead of sliding to the back

i think you could mess with adapter plates rather than the actual TB like the holley adapter seems to have taken this into account or some 'turtles' on the manifold floor etc etc

snflupigus

Well i was also thinking of maybe a single oval blade. Just something different.
Id never heard of having the injector spray outlining the blades. what if its to large, how would you get your injectors closer?

Also, the passages inside are either straight line holes that interconnect or something that could easily be cnc machined. Any experienced machinist should be able to cope. By the way. Ive looked at the tbi plenty, in fact i have one sitting right in front of me at this moment. My old oem.

And if i could study the injector pod a little more i would consider changing that too.

Pablo i know we kinda talked about this in a past post, when you and i somebody else were argueing how the regulator worked.
could you make a simpler one that was just a one way feed to the injectors. one line in. with an external regulator.
To me there just seems like a lot of room for improvement that wasnt taken by gm or anybody else because of the advent of tpi and others forms etc..

------------------
Gestapo?

ENGINE SPECS:
305 TBI,Open Element,K&N 14x3,Hypertech Stage I,160 Deg. Thermostat,454 GM TBI

STEREO SPECS:
JVC Kalmeleon kdlx3,Infinity Kappa 2way 6x9's,PPI 4x6 Coaxials,PPI PC2400 AMP @ 2ohm
DEI Studio 12" 4ohm DVC,Custom Box:Exactly 1 Cubic Foot

Pablo

iTrader: (1)

ive actually done a few improvements to the tbi and im still working on, like i said before you want the edges of the injector spray cone right at the edges of the throttle blades this will require an injector pod spacer and some grinding of the back of the casting

as for the regulator, i too have thought of a better injector pod, something less invasive to the space above the tb with no regulator just passages to the injectors and the actual injector holders. Currently i have an external regulator so on my motor i only have one fuel line to the tbi unit.

i wouldnt go with a monoblade unit if i were you and were gonna go all out id design a 4 barrel unit and some sort of hybrid injector pod to use gm injectors, or just machine it to use the holley 4 barrel injector pod even though those injectors bite
machining an injector pod could take some work though

Pablo

iTrader: (1)

oh and about the cone being too far out and hitting the sides of the bores

i think the main concern there is that under slight throttle opening the spray cone gets pulled off the sides of the bores if its not then its probably too far out

other concern is that the fuel could hit the side of the bore and bounce back to the center like when you take a leak into a urinal and get **** ricochet on your jeans

you probably want it just above the edges of the blades for the best performance
i have to play with it some more myself

FastBroker

Yeah, like Pablo says, just raise the injector pod until the spray is just at the outside of the throttle blades. Works really well. Just add another gasket (use two) and have to grind-up the housing in back to get the fuel fittings to go upwards...

Ever see a Holley 2" TBI? You will have a heart attack. The spray on those is so blatantly on the flaps it is almost funny... Sprays all over the place. Needs injector/pod spacer BAD!!! I guess the OEM/454 2" would do the same spray thing, eh?

Pablo

iTrader: (1)

yes the spray is horrible on the holley, it hits the middle of the blades so blatantly you see fuel drips bouncing off and out of the throttle body

the GM 454 TBI actually comes with a plastic spacer but im sure it could use more since i doubt they changed the casting for that purpose

snflupigus

Just to let you know, ive started measureing stuff out and drafting in autocad. In a week or two i should have a 3-d rendering of a brand new tbi, and injector pod.

Pablo

iTrader: (1)

Neat

88'camaro305TBI

iTrader: (2)

cool, let me know if you need some help with cad, i'm an archie.

------------------
Mods:Hooker Aerochamber 3" exhaust, gutted kitty,
March 2 piece underdrive pullies, smog pump gone,;these two made a very noticable difference.
14x4 K&N open air element filter-the best mod so far
Eibach springs with KYB's all around.
Appearance: Harwood cowl hood, Z-28 wing, painted black(7/20/00)-original color was light blue
*All these mods were made this year
Stock Options:117,000 miles on motor, 5spd, TBI, 305, T-tops
Run a best of 16.7 @85mph with traction problem. Have to try again sometime.

FastBroker

Pablo, in my experience with the Holleys, there is one thing you can fix/check to help the spray. If you'll notice, the injector spray hits right at the phillips head screw area on the blades. This causes the fuel to BOUNCE up and out of the phillips heads "hole" and out of entire throttle body. I have exhchanged injectors a few times in several throttle bodies just to get two injectors that do not spray out of the TBI. I have also used different (flathead) screws to hold the flaps on, which helped A LOT!

You may not have to worry about this w/your GM pod and/or raised pod, but for others that have plain-old stock Holley TBI's, it may help.

Pablo

iTrader: (1)

Yeah fast broker you are right on there thats a good point
fortunately with the GM injectors i dont get any fuel hitting them and bouncing up and out but i DID notice it with the holley injectors


Hey i found out some interesting new stuff you all might be interested in on this fuel distribution problem. IM gonna experiment with it some more i think i can clear it up substantially without a fancy tb check this out http://www.diy-efi.org/gmecm/papers/747Iac.txt

go down to "Mechanical effects"

I think i know whats happening now. At idle the air pulling the fuel past the throttle blades is real important, and if most of your idle air or alot of it is coming from the IAC hole then you arent getting a whole lot of air sucked through the throttle blades. That sucking past the blades is what shears/atomizes the fuel at idle and if there isnt any sucking past the blades then you can imagine that the fuel is just dripping off the blades onto the manifold floor. Im almost positive thats what is occuring on my car it seems like half of my idle air is coming from my IAC no matter what I do but that article shows alot of stuff to change to help the situation that im gonna try out


Pablo

snflupigus

i was thinking of eliminating the iac, i know gm engineers would disagree with me here, but i dont think air should ever bypass the tbi bores. i think the throttle blades should be adjusted automatically by the same sort of mechanism instead. isnt that how the holley works, doesnt it have a sort of small linear actuator to adjust the throttle blades instead of an iac. i dont know ive never seen one, just going off what i think i heard somewhere. I want to completely simplify the tbi, i think gm decided it would be easier for them to add the iac passage instead of clutter the throttle linkage. they could have made the tps both a sensor and a mechanism to either adjust the throttle blades themselves, and or monitor them and fuel all in one device. if you look at your tbi i think the iac looks like an afterthought anyway.

just my opinion. well see how everything turns out.

and Pablo, i got the same main idea from that article too. it totally follows what i just said. i just held my old tbi up to the light, and you can see that there is a small gap between the blades and the walls. when you open the blades a little, you see more light. i just dont like the iac passage and design. air just sneeks by, and sharp angles, in a completely different place from where the fuel is. it just doesnt seem right. they should have done it the way i described. and thats how im going to do it.

i cant stop thinking about redesigning this damn thing.

Pablo

iTrader: (1)

yeah actually the early holleys have a "kicker" i dont think the kicker is the best way i think the iac is actually better cause its more reponsive that nthe blades

i think the gm engineers have the design pretty down its that when we start modding our IAC counts go to hell


i managed to get my iac counts REAL low just now the motor is idling really nicely i think i just made a giant leap in my fuel distribution problems ill check the plugs in a few and let you know

that article describes ways to get the iac count down and they work, good stuff

snflupigus

is the iac strong enough to act as a kicker if moved to push or pull on the throttle linkage?
it moves about 3/4 inches total. if set up on the right axis it could open or close the throttle blades as much as you wanted, if it were strong enough.
To adjust idle you would want a pretty short axis (close to the center line of throttle blades), so that even if it moved all the way out, it would never push open the blades more than say a 16th of an inch rotation.
You would also have to have it push from the front of the tbi on the linkage so that it wouldnt get in the way of pulling on the cable.

The programing of the iac would work exactly the same. Only reversed so if lean it would extend instead of retract.

Could that be done, by reversing wires?

are you following me?

i know you think that the iac is a better idea but does what im saying make sense. isnt it smarter to have the air and fuel always interacting directly so as to increase atomization, and prevent fuel from just dripping around the blades and falling to the manifold floor.

note: edited to remove old pics

[This message has been edited by snflupigus (edited November 04, 2000).]

snflupigus

I think i just solved my problem of not wanting to use an iac passage with twists and turns, and seperating the fuel from the air.

Here is a first design thought



The idea would be:
The iac would pull comletely back into the wall of the bore,as a smooth wall(because the face of the pintle would be blended into the face of the bore), when the blades were opened. I could do this with the chip programing right? When at idle/blades closed completely, the pintle would move out to close the silloette (of pintle) hole cut into the throttle blade. and would work normally opening and closing to adjust idle.

I dont want to have to redesign a shaft,etc for the iac, so i think i would first build it as shown in the above picture.

Big question!
Would i get a lot of turbulance if i had a notch like that cut out of the throttle blade. And if i had an irregular recession on the bore wall where the normal pintle retracted into it?

Is that pintle just screwed on or what? anybody know? Because ideally, the above description of a new pintle that matched the side of the tbi bore would be better, and i could just screw a new one on.

GIVE ME YOU THOUGHTS. THIS IS MY LAST PROBLEM TO SOLVE BEFORE MAKING THIS THING.


[This message has been edited by snflupigus (edited November 04, 2000).]

snflupigus

Good news, the pintle does just screw on so it could be remade to match the throttle body bore.

Bad news, I think it rotates when it moves in and out.

Wait or not bad news, if it is a round hole in the tb bore, and the pintle's, radiused-bore-matching-face, is aligned when retracted the borewall will still be smooth with the blades opened. hmmm. It would also have to be aligned when it is fully extended(within the programing)so that it matches the hole cut out in the blade.

So the Iac's pintle could be remade so that it conforms to the tb bore and makes for a smooth bore face when the blades are opened and the pintle is retracted.

Ive taken apart my spare iac, and it looks like the shaft moves a total of 5/8 inches

And i think im going crazy right now, too much thinking. AAAAAAAAAHHHG.
Bare with me im thinking while typing here.

I would want to install the iac before the blades so that i new how to cut the blades. And i would like to have a chart of how the programming effects the length extension.

Number=length extended.

100 positions / (5/8)total extension length right?

If that is right i wouldnt have to install the iac first. I could calculate how far in to cut the blade so that the iac would be aligned with the cut, and i would want to make sure that the total area cut out of the blade would equal
a 3/8dia hole's area, (which is how big the iac's air opening hole is) which = pi*(3/16)^2 = .11 sq inches

Hope this is making sense to whoever is reading.

So ive solved a possible problem of have turbulance because of an iregular tb bore wall. but what about a notch cut out of the blade, they do this with carb right? so im assuming no turbulance because of it?

Gona go draw all this up. Ill repost dont you worry. he he

[This message has been edited by snflupigus (edited November 05, 2000).]

snflupigus

Ok, to anybody who read my very last post, I just realized that im retarded. That would only allow air to enter in on one side of the tbi, feeding only half of the motor with air. This would be bad im assuming.

But Feedback would be appreciated.

Im still thinking.

Also i was wondering if people would buy a casting that hadnt been machined at all, so they could build/machine their own? CHEAPER?

Grumpy

snflupigus

THE REDESIGN IS DONE.

Some Quick Specs:

1. 2" bores.
2. IAC relocated so it won't EVER interfere with your EGR again.
3. 1/2 inch tbi spacer built right in.
4. Two peices. Huh you ask? You'll See.
5. Injector spacer also built in.
6. Uses newest tps.
7. All vacuum lines are on the front.

Thats about it. After shes built I'll have pictures and hopefully some reasonable prices for resale.


[This message has been edited by snflupigus (edited November 06, 2000).]