help i cant find anything on carb to tbi swap

THERES ALOT OF WORK INVOLVED, FIRST YOU NEED A TBI SETUP, WIRING AND THROTTLE BODY, INTAKE OR ADDAPTOR PLATE. YOU WILL ALSO NEED TO GET THE FUEL PRESSURE UP DEPENDING WHAT YOU HAVE NOW FOR A FUEL PUMP. YOU WILL NEED A COMPUTER AND NEW DISTRIBUTOR, ALSO A WAY TO CUSTOM PROGRAM TBI CHIPS. A MILD CAM MOD WILL THROW THE STOCK COMPUTER WAY OFF. THERES ALOT OF WORK IN MAKEING THAT KIND OF SWITCH. BETTER DO A 350 TBI TO MAKE IT WORK YOUR TIME MONEY.OTHERWISE STAY WITH THE CARB AND KEEP EATING GAS

If you don't want to go thru a major mod of swaping everything out from the donor car, you can try the Holleys TBI see link Holley Performance Products Commander 950 Throttle Body Fuel Injection System*950-20S this is for application of 275 hp & lower, they have another kit for higher hp applications...

Good luck

I found this site and did alot of reading. It is a Scout site but they are using GM TBI systems for their conversion so everything is the same.
Did everything myself and had alot of fun learing something new.
The payoff is awsome, well worth the work. I am into the swap for less then 300 bucks.
Good luck.

Another option to consider as far as the computer goes is the megasquirt. MUCH more economical than Holley's setup.

MegaSquirt - Electronic Fuel Injection Computer by Bowling & Grippo * * ©2005

The learning curve is steep, but once your over it, you can fuel inject anything from a lawn mower to a boosted, n20, big block monster.

The tuning is more straightforward in this approach as well. Tuning the stock computer requires learning how that specific computer is programmed. All a megasquirt requires is a laptop with a serial port. Every bit of info you could possibly need is already organized in a FAQ on the site, so no worries about finding someone to tell you how to do something. All the needed software is free.

Just be sure to weight your options before making a descision. Keep in mind, no matter what option you take, you'll be dropping the fuel tank to install a high-pressure pump. I suggest the Walboro 190(mild) or 255(wild)

I'll play the devils advocate and say that the stock ECM is better than the MS.

You don't have to know computer programing to tune a stock computer, there is also a FAQ section on this site, and even a step by step walk through of how to tune your TBI motor on this board. MS does have less things to change, which makes it easier to learn. On the flip side of that MS is simpler which means it will never have the drivability of a stock computer.

The MS does have the advantage of being able to hook your laptop directly to your ECM. With the stock ECM you'll have to burn a chip and swap it in, or spend some money on an emulator that will tune real time like MS.

The MS is also much more expensive than the tuning equipment for a stock ecm. Once you make the investment in tuning equipment you'll be good to go for every GM ecm that came with a chip.

The last and most important feature of your stock ECM is the fact that you can get one at any parts store when it kicks the bucket. What happens when you MS wiring harness shorts out on your fire wall? Your stuck untill you can solder one together. I had this happen to me with my TBI ecm, and I was back on the road in 15 minutes. You just can't do that with MS.


Oh....you won't need to worry about programing if you stick with a relatively stock motor. You can just run the stock chip.

I beg to differ on the price. What does a brand new ecm plus harness cost? I'll be in for about $350 for the electronics related stuff for my conversion. That number includes: The latest MS, harness, and other misc. equipment(cables and such). I'm reusing the stock sensors(mine was L69) I don't know if the stock ecu can handle wide-band o2. That advantage alone is worth more than all the rest. It's bout $200 for either setup. With the upgraded map sensor, the MS can also read 3BAR(30ish psi) boost.

True that you must invest time to design your specific install and build your harness and such, but how many of us have more money than we have time. I sure don't.

The FAQ and tuning info on the MS site is so much better organized(please don't hit me). The MS team designed the MS from scratch, and therefore are intimitly familier with it. They also have a forum for assisting others and showing off new ideas.

For now, the MS is still in development, meaning it's still getting better day by day. It is open-source, meaning you can download the source and add ANY feature you would like. That would be another steep learning curve(Its programmed in C), but not entirly necessary. You don't need to be a programmer to use a MS. You could even hook up a computer activated nos system with little custom work.

From what I've heard around here, the stock proms leave something to be desired. Yeah its a starting point, but the MS guys give me one too.

MS offers free tuning and logging software. You can feed your datalog into a program and it'll spit out your new VE table.

And in the end, if for some misguided reason, you get something other than gm...well, I think the MS could even help it move under its own power.

Or even a lawnmower. That is flexablilty.

So...is this the info you were looking for. We came on kinda strong, but take some time to digest it before making a choice.

It's alottttttttttt of work did I stress a alottttttt ..... if you do it right with donor electronics it's even rough. I did my 82 trans am using every piece of wiring from a 1990 firebird, then you have the fuel line issues ... everything is a time consuming issue took me about 3 months to complete mine.

Yes I know thats along time but keep in mind I also replaced the fuel tank and all fuel lines, dash had to be removed and new dash harness installed, had to put in the 1990 heater box. I even installed vats in my car as well. which meant column replacement ..... then when you update the dash harness all the other older harnesses are useless that includes tail light harness and headlight harness. And when you do that then you wind up with headlight motor changing, yours being a camaro wouldn't be a issue though nor would the tail lights. .... it goes on and on ...... but worth every hassle for a better running and driving car and one that won't be a electrical nightmare. And if you ever plan to seel the car nobody will want a car that it's electrical system has been hacked to make a TBI system work .. and this is my primary reason for doing my car this way.

best bet for you is to just buy a painless harness and go that route or take your berlinetta dash and put it in a later model car either way your in for a nightmare ... like changing sensors, distributors. etc. etc.

KEEP your car carburated guy thats even better advice

I just wanted to stop in and make a few comments, I don't really want to start a MS vs. the big bad OEM argument, but I think your ignoring a lot of the facts.

I'm sure if you went to GM and asked for a TBI ECM and harness it would be well over $2000. The key here is there is an endless supply of ecm's at EVERY parts store that will sell you one for less than $100. As for a harness, you can use a stock junk yard harness or go to painless for a direct plug and play. With MS you'll be making your own, which is a LOT of work.

You are correct when you say that the stock programing leaves alot to be desired, the thing is it's way more advanced than MS software. MS is pretty crude in a lot of ways. This also works in it's favor in that it's very simple to tune, you just have a few tables and modifiers to mess with. Unfortuanately simplicity isn't always better when comes to making an ecm control an engine. As for "add ons", Rbob recently released his EBL system which fixes every issue with TBI and give you every performance oriented code doodad that you could ever want.

BMmonteSS, I'm not trying to badmouth OEM(I see how it looks like that though), I just enjoy the discussion. We learn things by discussing. I'm actually quite unaware of exactly what the OEM ecm is capable of feature-wise, and I wouldn't mind learning.

I didn't know the cost of an OEM convert, but with used or non-factory parts it appears it could be done cheaper that way. Just make sure to include the cost of chips and burning equipment as well if you want to change anything.
And besides, if you've decided to do this kind of conversion, you're already in for a lot of wrench/wire time. What's wrong with a little more? I think that's the second funnest part(driving being the first). To me, paying somebody else to do something I can/want to do is just wrong.

I haven't mentioned the fact that MS can actually piggyback onto other systems. This means you could run a vac. advance dizzy to control spark and get a downgraded MS unit for cheaper. I'm running a dizzy from a L69 carb car. It's got electronic advance the the MS controls.

I think they both have their own high and low points, but I went the MS route.

Didn't some famous philosopher say, "The simplist solution...something"

Once I had the harness out of the "DONOR" van, I cut all the unecessary circuits out and made a TBI harness. I then combined the TBI harness into my vans original harness. Some looming tape and some wired looms cleaned everything up. I used the donor vans fuel tank, fuel lines, harness, distributer, ECM, wiring, TBI, etc. I originally left the stock carb intake on my old 305 and used a stock GM 454 TBI and GM TBI-Q-Jet adapter. I had an o2 sensor bung added to the driverside header and installed a 3-wire oxygen sensor. I bought an add-on 3 fuse, fuse block and added the necessary wires to the existing harness. I soldered all the connections. From start to finish it took about 1 month of spare time. The actual down time was about 3 days working 10 hours a day.

HOWELL TBI

This is how it sits today, with the addition of a Weiand 142.

Sorry to dig up a dead topic. But, I was searching on Google and came across this post and several others. MonteSS, you seem to have something against the MS. the stock ECM from GM is NOT superior in any way to the MS currently available. It uses a slower processor and is not nearly as flexable as the MS. You say with MS you will be making your own harness, thats not true at all. A 6' MS harness is $60 with the ECM connector already attatched. I dare you to show me a custome TBI harness for under $200. You can't.

Secondly, tuning a MS is MUCH simpler than tuning and burning chips. I have tuned everything from TBI, to TPI GM computers, Holley Commander 950, ACCEL Gen 7, f.A.S.T and Megasquirt systems. The MS was by far the easiest and most intuitive to tune. Have you ever tuned with the MS software? Maybe your bias is based on lack of experience.

Then theres the whole other issue of expandability and added features. Something which is non-existent with stock ECMs. The added features alone make it vastly superior to the outdated stock ECM. True a stock ECM has it's place, on a stock motor you are not looking to modify.

There are even adaptor boards now to allow you to simply mount your MS board into an empty 746/747 TBI ECM shell. Plugs directly into the stock harness. Now how much more simpler does it get? You obviouslly have something against MS calling it "crude". Whats crude is clinging onto burning outdated chips and having to swap them in and out everytime you wish to tune. Plugging a USB cable in as you're driving and tuning is the obviouslly more refined choice. Unless you like doing things the hard way?

MS has proven itself to be very capable as earlier mentioned. Powering everything from single cylinder lawn mowers to 10 second LS1 turbo and nitrous powered trucks, to 16 cylinder diesel pulling trucks making over 3,000 horsepower. Now show me a GM ECM capable of that.