The Stovebolt Site Forums The Shop Area Engine Shop TBI on a 1959 235

I have read a bunch of threads on this topic, but most have to do with using something other than the stock intake manifold to make it happen. My question is this, starting with the 4.3l TBI is it possible to use a 1bbl to 2bbl adaptor off of the manifold and then use a 2bbl to 4.3l TBI adaptor to mate the TBI unit up? I suppose you could even have a machine shop machine a plate that goes directly from the 1bbl to the 4.3l TBI.

Am I totally overlooking something that would keep this from working? I know there are a lot of other wiring and computer issues, but in theory would it work with the stock intake and the adaptors?

TBI is a very crude fuel injection method, but it's about 200% better than the best carburetor if the computer is given the right information. As long as it gets adapted to the intake with no vacuum leaks, I don't see any reason it shouldn't work. You'll need to do a LOT of adapting of the sensors, and it's a crapshoot whether the V6 PROM will work with the information from the stovebolt engine. Once the injector is adapted to the engine and supplied with the right pressure fuel, it's all a matter of tweaking the computer.
Jerry

I do a bit of Jeep tweaking as well, and the junkyard TBI has been a popular topic for awhile. Here is a thread with all sorts of good info on the project: http://www.viciouscustoms.com/TBI/junkyardtbi.asp.htm

I don't imagine it woud be much beyond the scope of this project on an Apache. Maybe I am wrong, but I am seriously exploring the possibility.

How much of an issue might there be between my engine, which is the 235, and the 4.3l which is a 265? I mean, having a computer that is dumping enough fuel for the 265 into a 235.

I have been reading up on TBI to try and swap it onto my '77 Jeep w/ a 360. There are a ton of articles out there but I think this guy has one of the best info pages on it, http://www.binderplanet.com/forums/showthread.php?t=47254

Blake,

Yeah, I e-mailed him last night. He definitely knows his stuff and is very helpful. If I go this route I will do a write up for the install. What is nice, while not cheap, is that if there are computer issues related to the swap, Bill is able to reflash the computer for the appropriate specs.

I found a guy on Craigslist with everything that I would need from the donor vehicle, including the distributor, for $250. I am trying to figure out what it would cost at a salvage yard, plus how long it would take me to pull everything.

4.3 is a 262. The slight difference in air volume won't be critical, as the O2 sensor will fine-tune the mixture once the computer goes into closed loop operation. You'll get a slight over-rich condition on full throttle acceleration, but that's also a good thing. Most of the race engines we checked on the dyno had a wide-open mixture of slightly under a 12:1 air/fuel ratio instead of the 14.7:1 stoichiometric ratio that the O2 sensor is looking for all the time.
Jerry

That's good news. I am getting pretty excited about this possibility.

I found a machine shop that will make the adaptor for the 1 BBL intake to the 4.3l TBI. I am sending him my carburetor gasket tomorrow for the mock up.

Went to the junkyard today down in Tulsa and got most of the parts I needed from a late 80s S10 with a V6. I even found the desired computer in another late 80s Chevy truck, number 1227747. All in all it was a good day, and tomorrow I will sort though what I picked up just to see where I am at.

I intend to put the pictures up on Photobucket as I go along and link them here.

My goal is to do this as inexpensively, and yet as cleanly as possible. Because of that I sourced my inline electric fuel pump from a mid 80s F150 (basically it is the interchange part that this guy in the link below purchased from Autozone), and I pulled the O2 Sensor with cost savings in mind as well.

My primary source for info is from this link: http://www.viciouscustoms.com/TBI/junkyardtbi.asp.htm

and

http://www.binderplanet.com/forums/showthread.php?t=47254

I may be wrong, but I think that fuel pump will put out wayy too much pressure for a throttle body set up. If I'm reading the specs right about the pump it says it has a minimum pressure of 90psi and a max of 100psi.

I think the GM TBI take a much lower pressure pump so you may want to check that out.

I looked at the specs on Autozones web site.

Roy,

Good question that I do not know the answer to. The E2182 is one of the recommended pumps on many of the discussion boards. After I read your post I double checked and noticed that I pulled what would be the E2000, a part number suggested on Binder Planet. The E2000 does flow less, 30PSI up to 90PSI.

I still think that is too much for a GM TBI set up. Seems like they run closer to 18 - 25 psi or so. If you get one too strong, the pressure regulator could rupture and flood the engine.

It's been a while, I'll have to look up my notes.

9 to 14 psi spec for tbi systems except 94-95 454 trucks

From Bill at Binder Planet: "Pump has nothing to do with pressure, that's the regulators job." I will have to do some checking regarding a regulator as I have not seen anyone discussing that part of the swap.

Thanks for catching that!

Just found that the regulator is built into the TBI...

The regulator on the TBI set up will not handle that type of pressure. It will rupture and flood the manifold. Ask me how I know. LOL

Get the right pump with the right rating for the TBI and save your self some head aches. It will over whelm the pressure regulator in the TBI.

Roy, I asked about your question over at Binder Planet and got this response:

"...it has been used by thousands of people doing this conversion.

The answer lies in the system design.
The regulator is on the outlet side of the injector. So it maintains the pressure constant from the pump to the injectors.

You can see this http://www.binderplanet.com/forums/showthread.php?p=298293#post298293 for the details on how it is set up."

At this point I am going to move forward with what I have, and will describe any issues I may come across with this setup. Thanks!

Well sir, let me know how it goes.

Roy I definitely will. Know that I will appreciate any input along the way as well.

It's pretty straight forward. I've done a couple so far and it has been fairly easy.

Most recent I set on up on a 36 F... that I helped build. We did use a small block Chevy, but had to make the wiring harness, install all the sensors and so on.

Runs pretty good.

Only other advise I might give if you haven't already thought of it, use as much steel line as you can for your fuel lines. Keep rubber lines to a minimum, and make sure they are rated at the pressure you will be running.

Use good clamps on those rubber lines too.

I used an in line pump and installed a return line in the sending unit body so we could retain the original tank and sending unit.

Do you have any pictures of the return line in the sending unit body? I figured I would need to do something like that but I have not been sure how.

For fuel lines, are the braided SS lines ok?

"Edited by kjhibbs (Yesterday at 06:44 PM)
Edit Reason: The quote from Binder Planet came across a bit rudely."

Sorry if it came across that way.
I have been playing with GM TBI and MPFI for more then 10yrs.
I have just about everything documented for the DIY'r to successfully install and tune a system on just about any engine.
The fuel injection system really doesn't care or know what engine it is bolted on. So as long as you tell it the basics and install it "correctly" it will run.
Then the fun starts with the fine tuning. Most just get that glossy look in their eyes at just the mention of tuning EFI. But it's not as bad as you think.

The main thing to remember is if a guy selects a complete system from a donor that most closely matches his, then the system can be installed and driven without making any tuning changes.

The tuning optimizes the system to your individual engine.

There have already been a couple links to binderplanet.com injection forum posted on here so there's no need for me to copy and paste all the specific FAQ's I have put together to guide someone thru the complete conversion.
But I have used the same very basic GM tbi system to install on a 4 cyl classic minicooper with DIS-distributorless ignition all controlled from the ECM, to 500cid caddys with the BBC 454 throttlebody.

The stovebolt is a pretty common I6 and the TBI will work fine. Just like the Carb, the long manifold will cause slight lean on the outer plugs and slight rich on the inner.
A swap to a dual carb manifold and simply running 2- 1 barrel throttle bodies will definately help.

But they aren't race motors so 1- 2 barrel throttle body will work fine.

My next I6 project will be MPFI with turbo, just cause I can.:)

Oh, as for the fuel pump, I run the same type pump on my TBI and my MPFI projects and my customers. No problems, no issues. I run them external with a clear G3 style filter on the inlet side to protect the pump.
I have never had a pump failure.

The only way the regulator can ever see high pressure is if the return line gets pinched or restricted so the fuel returning to the tank gets blocked.
As the return line pressure increases then inlet pressure increases.

I recommend 3/8 feed and 5/16 return lines.

Well bummer, it looks like I was in a rush at the junkyard and ended up pulling everything form a 2.8L V6, not the 4.3L. From what I understand the difference is in the injectors and the TBI bore. Taken from Bill's website:


Injector sizes-
Color code Black/White
Engine 2.8L
Flow lbs/hr @ 13psi 33
TBI bore 35mm
GM part # 5235430

Color code Yellow/Blue
Engine 4.3L
Flow lbs/hr @ 13psi 45
TBI bore 43mm
GM part # 5235203

Is this going to be a deal breaker? I believe the wiring harness and the sensors should all be good. But I may have to get a different TBI...

Or you could just go ahead with what you have. After you get it installed and running well you can consider adding an additional TBI unit to make the mixture more even, or look around for the slightly bigger TBI unit from the 4.3. I expect you'll find the single smaller unit to work just fine. It supported 125 HP in the S-10 application.

regards,
Leon

That's a question I had re fuel system compatibility... Is engine displacement the comparable number? Or is engine output a more accurate measure of what is needed?
IE is a system for a 120hp engine going to be a closer match to a basic Stovebolt than one from a 235(ish)ci engine that puts out 225hp? I would think that putting in the fuel needed for the output hp would be more accurate, but I've been (very) wrong before.

Both are used.
The injector need to flow the required amount of fuel to support a maximum HP while maintaining an "on" time of not more the about 80%. This keeps them from going static or on all the time.

The engine displacement also comes into play when calculating the proper BPW-base pulse width that the computer uses as the baseline injector pulse. Then it adds and subtracts from that.

Now it's fairly easy to make a larger injector from a smaller one by simply increasing the fuel pressure at the regulator. (see the link earlier in this thread)That way the injector sprays more fuel each time it open for the same amount of time. It also helps with the atomiztion of fuel.
GM did just this in 1994 when they changed the 454 TBI fuel pressure from 13psi to 25psi.
In doing so they went from a 80#hr injector to a 50#hr injector. But by increasing the pressure it now flows the same as the 80.

But like I stated earlier, chose a system from a donor that most closely matches yours.
The big 4 or small 6 can go either way but then the netres chip comes into play if you want an accurate limphome.

I have decided to swap the TBI out for the appropriate 4.3 TBI. Fortunately the salvage yard has a 30 day exchange period, so should not be an issue as long as I can get down there.

I am working on getting the intake / exhaust back on the engine (which is pulled, and nearly rebuilt), and then I am going to pull the cab and its internals off of the frame tomorrow. Once that is done, I am going to start working with the wiring harness. Bill has some helpful stuff over at Binder Planet, and there are other good resources that should help me sift through that.

Here is a link to my truck and the progress I have made thus far. I will ad picks to this album of the TBI swap along the way.

http://s1130.photobucket.com/albums/m537/kjhibbs99/Apache%20Rebuild/

I know this might be branded a heretic for this suggestion, but why not look in the Ford direction. The 3.8 V6 in the Fox body LTD's and TBirds used a 2 injector TBI setup. I believe it used a 2bbl Holley mounting flange. Another one to consider may be the 84-87 Tempos and 4 Cylinder Taurus with the CFI injection. They had a single injector setup that mounted to the manifold with 2 bolts, similar to a 1 bbl carb. The fuel pressure regulator was integral to the throttle body also. It may be on a 4 cylinder car, but I don't see any reason it wouldn't work on a relatively stock 235. Instead of using a factory tune, It would probably be really simple to use something like a MegaSquirt to adjust the pulse width and ignition timing.

One handy thing with the gm TBI set up is that with a scanner you can see a data stream of what is happening with each sensor that's on the engine as it is running.

On the Ford system I don't think you can. Or at least my Snap-on scanner doesn't. Even the earlier port injected engines for Ford only give me trouble codes, no data stream.

I like to see what each sensor is actually doing.

Roy, that may be true on the early Ford OBD1 systems. It's been a long time since I wrenched on any. The good thing about them is that they were relatively simple. You didn't even need a scan tool, you could actually hook up an analog multimeter to the OBD port to get all the codes. You could also check the resistance across the sensors to see if they were functioning properly.

This is going off topic for this thread but you would need to spend some time studying the system to know why.

I am a blue oval guy and I have been playing with converting carbs to EFI for over 10yrs. If the ford was easier or better then I would have used it.
Yes the throttle body bolts on easier but that's where it ends.
The GM computers are hacked by the aftermarket/auto nerds so everything is avail for free to tune them yourself.

I am not a big fan of aftermarket computers like fast or megasquirt due to availability.
If you break down who can fix it and where/when do you get parts.

The GM TBI was used on about 4 million vehicles and is everywhere including the parts stores and junkyards. So "if" I ever break down I can get the parts I need right then.

i do use a couple ford parts. I convert my old distributors to electronic using the ford duraspark pick up and reluctor. Same as the MSD probillet distr.
I also use the 4.9/5.4 yellow injectors for my MPFI conversion. They are everywhere and cheap.

And yes with a little knowledge you can read each sensor with a meter. But you can also pull into the local autozone and have them plug the scanner in and just tell you what is wrong. Or just jumper 2 pins on the aldl connector and count the flashing on the SES light. Just keep a little cheat sheet in the glove box.

HTH
Bill USN-1

Sorry for the glare, but pretty much finished up the engine:

http://i1130.photobucket.com/albums/m537/kjhibbs99/Apache%20Rebuild/803817dd.jpg

I am just waiting on the TBI adaptor...

Got my adaptor today, it is made of Phenolyn, and is highly heat resistive. I will fit it to the intake when I get a chance.

http://i1130.photobucket.com/albums/m537/kjhibbs99/Apache%20Rebuild/fd518c29.jpg

http://i1130.photobucket.com/albums/m537/kjhibbs99/Apache%20Rebuild/d022d107.jpg

http://i1130.photobucket.com/albums/m537/kjhibbs99/Apache%20Rebuild/7d4f3e94.jpg

I hope you don't intend to use the generator with the tbi system

Was planning on it, any info as to why that's a bad idea would be appreciated.

Said and done I want the system to look moderately stock, so I pulled an air cleaner from the donor vehicle and chopped out the mounting base and did the same on the base of my 235 air cleaner. I welded the two together, sealed the inside gaps with Copper RTV, and now will be looking for an air cleaner element that fits inside. Here are a few pics of the process:

The air cleaners side by side:
http://i1130.photobucket.com/albums/m537/kjhibbs99/Apache%20Rebuild/d091f763.jpg

Donor mounting base next to the 235 air cleaner:
http://i1130.photobucket.com/albums/m537/kjhibbs99/Apache%20Rebuild/1290fa22.jpg

The two welded together:
http://i1130.photobucket.com/albums/m537/kjhibbs99/Apache%20Rebuild/5596d1cc.jpg

Painted up and sitting on the TBI unit:
http://i1130.photobucket.com/albums/m537/kjhibbs99/Apache%20Rebuild/86d771a7.jpg

The generator is not know for a very stable voltage output.
If you can tweak the regulator to maintain a constant 13.8-14.2 volts at the battery then you should be fine. O zero out the voltage compensation table in the ECM's program so it won't compensate when the voltage drifts.

The 10 and 12SI is better if set up properly. Use the info at www.madelectrical.com for those. Read about the proper setup of the sense wire.
The newer CS series of GM alternator was designed for the newer EFI systems with a much cleaner voltage out. They can be a direct swap for the SI series.
So the CS is the preferred. The standard is a CS130 so there is plenty of amps there to play most any accy.

Looks great, are you using a stock 1 bbl manifold or a four bbl manifold like the ones from clifford?

i doubt a generator can keep up with the current requirements of the fuel injection system and anything else on the truck

Keep in mind that an EFI system does not use much current.
That's really not the issue. A clean constant voltage is a concern.
The injectors out put can vary with a change in voltage along with the fuel pump output. So at low voltage you get less fuel. This can play havoc with trying to tune the EFI. But, the GM system is capable of learning and will adjust and compensate for some of the variables.

The biggest draw is the electric pump and the ignition. So if anyone with a carb has installed an electric fuel pump then it's really not much different.