Inliners International Forums General Discussion Hi Performance Throttle Body Injection

Has anyone ever replaced their carb with a TBI unit....They say that you can easiely swap it and it is way more efficient...This doesnt make sense as i would think this unit requires a computer to control it. Either way any input would be great..

See www.lindertech.com for Jim Linder's shop in Indianapolis; his 1940 pickup with injected 292 (complete with computer) is featured in the "Rides" page of the Inliners website.

God's Peace to you.

d

its not EXTREMELY simple, but it is relitively easy...just have a discussion on this on another forum...here's the link. hope it works

http://fordsix.com/forum/viewtopic.php?t=16024

Hi Jason,

Wow, I feel like I could write a book on this....

I went from Rochester carb to multi-point FI and now to TBI.

Yes, a computer is required to run the fuel injection, and this part is a bit complicated. But, the upside is that the mechanical side of the TBI is way simpler than any carb.

On the computer side, you've got two approaches:
1) use a tunable computer that can be setup with a laptop or handheld.
2) use a factory, non-tunable computer and get a custom PROM made for your engine.

I went with option 1, as the computer side of this doesn't faze me at all.

However, don't underestimate the amount of time to fit up EFI to our inlines. There aren't many off the shelf parts to solve every problem, so a lot of thinking and fabrication is needed.

The eventual upside is much better starting and cold running (just like a new car).

I'm starting to think that dual TBI is the ultimate arrangement, because of the equal length runners to each port. Maybe I'll get here one day.

Greg

in the link i attached one guy said that the tempo, topaz and old taurus 4 cyl single bbl TBI's are direct bolt on if u can bolt on a carter YF(A) 1bbl...so if u only want to do 1 TBI in place of the carb, then it should bolt on..then u just have to worry about the computer and the fuel return line...i would get the fuel return line done at a shop, and DONT weld it.

with the programmable modules, do u buy a disk or something that allows u to tune up the module?

292C10

Why did you go away from the multi port FI and go to a TBI setup? I'm thinking the multi port would be cool and not that much harder to do. I ran into a guy with a multi port on a 292/th350 and he said he only gets about 10mpg. Not what I'm interested in.

Gael

The computer is tuned using software that is provided with the computer. There are loads of parameters to adjust, but the major item is a fueling table that has different load and rpm points on it. THe computer consults the table for where the engine is currently running and injects that amount of fuel. The extras add acceleration enrichment (accel pump), etc. that are needed for a real application.

Why not the multi-port? Seems like an obvious question doesn't it? Well, in my case, I ran across an unsolvable problem (2 years of screwing around). At certain load points, the engine would stumble for no reason, but if you moved the throttle at all, it would clear up and run on. I tried richening, I tried leaning, but no adjustments ever seemed to help. I'd already been over the manifolds to make sure they weren't leaking and that all injectors were working properly. Further investigation of the spark plugs and exhaust ports in the head showed that cyls 1 & 6 were running lean, but 2,3,4,5 were all rich.

I've since come to the conclusion that one of the following is happening:
1) air travelling down the manifold runs on the outer wall around the corner into 1,2,5,6 with the result that 1 & 6 are being ram charged to a degree, leaning these cylinders.
2) reversion is happening in the simamesed intake ports such that the air/fuel mixture is not ending up equally in both cylinders at certain rpm points.
3) the multi-point injection events are timed such that injectors 1 & 2 inject closely to when intake 2 opens, thus 2 gets more of the fuel charge.

I have further opinions on these 3 ideas, but the bottom line was that how could any of these problems be addressed?

So, for kicks, I grabbed a TBI off a 3.1L GM Lumina van for $25. I stuck it on where I had had the progressive 4 bbl air throttle body. I then changed the injector wiring to fire the TBI, not the MPFI. A bit of computer reprogramming later, and bingo, the engine was running again. Pretty quickly I noticed that the areas where I used to stumble most frequently were gone. This makes some sense since the original carb had never stumbled like the MPFI did. Also, I didn't lose my great EFI starts, so I'm pretty much sold on the TBI idea for these engines.

I have one minor problem to fix (keep this in mind if you do a TBI swap). The injectors that come from the smaller TBI unit (model 220, regardless of injector size) with 1 3/8" bores (S10 trucks, all the 60 degree V6 stuff) are rated at 33 lbs/hr each. This isn't quite enough for my otherwise stock 250. When I was running MPFI, I was using 19 lb/hr injectors, or about 120 lbs/hr total. Now I'm at about half that. So, I can't floor it above about 2500 rpm or it'll lean out since the injectors have gone static. I'm going to swap in a set from either a 4.3L or a 5.7L (350). You could just swipe the TBI off a larger engine in the first place, but at my yard the small V6s are way more common than the V8s. Also, I'm not convinced that the smaller bores of the V6 are a problem. I think they still have enough area for the inline. The 4.3/5.7 use 1-11/16" bores and the 454 uses 2" if my memory serves.

Anyhoo, that's enough of that for this post.

Greg

instead of getting a V8 TBI would it work just as well to adapt 2 TBI's from a 4 cylinder engine and have them at the 2nd and 5th plenum, then just block off the main carb area in the center...also i was just thinking...what about kickdown...is that controlled the same way with the rod? If i were to adapt 2 TBI's i would definitely have to get rid of the kickdown rod thats there...any way of doing something with that, or will i just have to shift manually? I do that most of the time anyways. Thanks for sharing your knowledge guys.

An instructor and I were just talking about this a day ago. The TBI setup seems like the easiest way to go. What distributor are you using with the FI though? That's where we were kinda stuck. I do like the idea of multiple throttle bodies though. Would they just fire in batch, or....? Thanks. John

with multiple TBI's they would all fire at once...u can hook up to 3 TBI's to 1 computer module without a problem. so using the offy tri carb setup on the engine would be very good for something like that...How about the 2 outer TB's oked up in synch and the middle one as a progressive? that may be better for a larger power band and less off the line lag...when i bored out my carb, i had to enlarge thejet twice the size and set up the accelerater pump to shot a fair bit earlier...i think it would sorta be the same with the TBI setup...it would need a larger amount of fuel being shot and result in not too great gas mileage...any professional opinions?

I have a 54 GMC PU with a 302 in it. I have been running a TBI system on it for a couple years now. It works very well. I took a complete system off an Astro Van with a 4.3 V6. I took the entire wiring harness out of the van and laid it out on a piece of plywood. Then I took a wiring diagram for the van and cut out what I didn't need. I used the computer from the van as it was. I found an externally mounted fuel pump that is a replacement for the TBI in-tank pump and mounted it on the frame. I got a 4BBL intake from Patricks and modified it by cutting out the dividers in the plenum and making an adapter to mount the TBI out of a piece of 1/2" steel plate. I had to modify the distributor off the V6 to fit the 302. That was the hardest part. I think you could use an HEI distributor with the 5 or 7 prong module if you knew how to wire it up, but I didn't know how. It would have been much easier because I was already running HEI. The only problem I had was a fairly frequent lean backfire. I replaced the 4.3 throttle body with one from a 350 and it works just fine. I guess I may have done it the hard way, but I don't know much about computer systems as far as changing or reprogramming, or about lbs.per hr. injectors or any of that stuff. The best part was that it was all free except the fuel pump and intake manifold. It is also simple--all parts are available from any parts house and diagnosis is the same as the stock vehicle. Oh, I forgot, I also bought a speed sensor to hook up to the computer. Maybe this will help. Joe

Sorry for hijacking the thread but I love simplicity and lack of electronics. The FI setup would be great for a converted (12V) truck, however this is the setup that I'd want under the Christmas Tree.

K.I.S.S.: I had a setup on an old 280Z like this. What a hoot. Not the easiest to tune with the cam I was running (too much!) but when it was run hard it really pulled hard.

http://www.piercemanifolds.com/Images/Catalog/K353
.htm

Back to your regularly scheduled program with my sincere apologies.

Tom

Blazing Saddles:
I don't suppose you've got any idea what the cost of that would be? Went to the website and parused, bbut for the life of me I can't find any referance to price. (hope I didn't miss the obvious)

Thanks:
Paul

Unfortunately, it won't be cheap. The last set of these I bought was nearly 25 years ago and it was pretty hard on the wallet. I made an inquiry and can pass along the information when I receive it from Pierce.

Best regards,

Tom

I agree that two single bbl TBIs could be used in place of a single 2-bbl. I may try this eventually. The easiest way to do this on a chevy is probably with a dual 4-bbl intake. With the aftermarket computer I'm using (Holley Commander 950), it can drive up to 4 TBI injectors.

Trueslayer, you'd probably have to fabricate some kind of setup to attach the kickdown cable to the TBIs. Although, this may not be too hard because the GM TBIs already have an attachment point for the TV cable used with the 4 speed autos.

bigchevy, I'm just using a stock HEI distributor, since the aftermarket computer doesn't require an electronic distributor. It can, however, utilize crank triggers, etc. if you want it to control the spark timing as well.

One other thing that is messy about the multi-port setup is the location of the cyl 3 & 4 injectors. There's not much room between the throttle body and the head!

Tom, there are times when I definitely agree with you, and that multi-carb setup looks great. However, for that cost you could go EFI. So then it's just a matter of which you're more comfortable with, and I'd rather tune EFI than that carb setup!

Greg

All
Good reading and a timely find for me.

I am adding FI to a Chevy 250 for my son's 72 Ventura. I am using a self-built control board/interface from a group of experimenters (MegaSquirt). I initially wanted to go Multiport but realized that I would need Cam & Crank position sensors and added programming to get around the shared intakes. The results 292c2 saw verify my research. So for me, a single TBI is the plan. I have a spare supercharger laying around and eventually want to adapt that. When I do, it will be easy to modify the setup using a laptop.

Engine is still in pieces so I will let y'all know how it goes when I get it done. I really like the build/learn it yourself situation. (Cost is nothing compared to commercial ontrollers...if you know a little electronics/can solder/wire one of the experimenter boards/systems can be fun/effective.)

Rock

Hi Rock, and welcome to the board. You know, if the MegaSquirt had been around when I started on EFI, I definitely would have used it. I'm a sometimes electronics junkie and I had starting contemplating building (designing) my own EFI controller, but time meant it was never going to happen. So, I went with the off the shelf solution.

For the TBI, you've probably found on megasquirt's page a listing of the different injector sizes. If not: http://home.earthlink.net/~jcgebhart/msindex.html

I'm still using the 33 lb/hr 2.8L injectors, but I want to switch to the 55 lb/hr 5.7L (350). I still had lots of growth room with the multiport injectors at 6*19 lbs/hr. So, the pair of 55s will give me 110 lbs/hr, which is enough to support about 220 HP (ya, right). However, I am going to switch to a 292 as soon as my 250's had enough (I'm starting to wonder if that'll ever happen, as the thing is 30 years old this year), so I want to have enough flow.

What intake are you going to use?

Oh, and swipe the air cleaner housing and fuel lines off the TBI you use. It will make things a bit simpler.

Greg

I found a price for 3 45 DCOE's at roughly $1435 US. I've done a fair amount of carb business in the UK and they always seem to have a good supply of Webers and Dellortos plus parts. A Clifford manifold is another $320 so it's not going to be cheap (just like I said) . We'll see what Pierce has to say. It should be better, especially considering shipping and the fact that the dollar is in a pretty sorry state vs. foreign currencies.

Good luck,

Tom

Here's another interesting site:

http://www.twminduction.com/

Tom

Blazing Saddles:
Thanks for the info and the new website.

Sincerely:
Paul

Rock, would it be possible for you to do a write up on your FI conversion? I know everyone on here would greatly appreciate the shared knowledge. I'm planning on FI, but I'm thining about multiple TB's and eventually a turbo. At least the multiple TB's for now.

I'm also very interested in the Megasquirt setup. I've been to there site, but I'd just to here from someone who's done it already. This is some great info, guys. John

EDIT: This would be a nice setup for TB's.
http://www.twminduction.com/ThrottleBody/ThrottleBody2900-FR.html

Hi, I don't want to hijack someone else's post, but I am also considering a 2x2 TBI set-up. It all seems pretty straightforward except for connecting the two TBI units to one computer (ECU). It seems like using two GM TBIs from the 2.8L V-6 would be just about right for my application for fuel flow and air flow. This set-up would allow me to use my Buick factory dual carb manifold which has much better flow distribution and also dual exhaust than the single carb manifolds.
I'd like to know if it is at all possible to use two GM TBIs with one GM computer? I am planning not to use spark control due to the costs involved in modifying a distributor to work with my straight 8. What options do I have for sensing engine speed? Can I connect to the original distributor if it is equipped with points? Petronix module?

Jerry Woods Enterprises has been playing with these systems on some pretty high strung 911 Porsche engines. He's making some horsepower.

Tom

A must if you're going to play with TBI...

www.thirdgen.org

A wealth of info...

Chevytown fo life!

Just got back from a trip with limited web access so I was not able to reply earlier. Appreciate the info and I will try to come up with an article on my FI "experiment". I am currently on the road a lot and my boys keep filling my free garage bay with other "emergency" projects. Will let you know when I start to make progress.
Thanks
Rock