BrightRed93Z28

I was wondering if anyone knows what all is involved in a carb to TBI swap? I'm thinking about buying my friends 305 for my 81 Firebird, but I don't want to keep it carbed. I want a good, cheap fuel injection that will make decent power. Hence, the TBI Swap. I know that I could also do a TPI swap, but the kits are pretty expensive, and I'm not looking for anything special, just something to get me to school and back everyday and also some around the town BS but not bust my wallet on gas $$. So I was going to have the 305 heads ported and polished and stick in a stock LT1 Cam, some 22# injectors, and get a chip burnt for it and go from there. But before I worry about modifying it, what all is needed for the carb to TBI swap? Thanks!

dimented24x7

iTrader: (2)

The tbi will work fine. Youll want to at least get some 55 pph injectors and a good in-tank fuel pump. With the cam and heads, youll need chip work. You can purchase the equipment for not too much but there will be some time investment in learning to tune the system. I would not recommend getting someone to do the chip work for you. Theres just no way they can tune the car.

Youll need:
Any old laptop
Burner
'G2' adapter + flash rom chips
Some form of tuning software. I like tuner cats but it costs money.
Some basic mechanical stuff, like a vacuum gauge. I like to keep one next to my tach while im tuning so I can see where I am on the tables at a glance.

Do a search on the prom board and here. There is tons of info on this.

The tbi itself should be relatively straight forward to install. If you can, see if you can get a copy of the chiltons camaro/f-bird manual. Some copies floating around have the FULL reprint of the factory f-body wirng diagram manual rather then that crappy single line stuff that they like to toss in there. The wiring diagrams will make things easier for you.

BMmonteSS

You basically need the wiring harness, TB unit and related sensors, you'll also need a vss sensor which your bird might not have. On the fuel side alot will depend on what you can get for your 81 bird. I suggest an internal pump in the tank, but none were ever offered for 2nd gen f-body's. I'm running an external pump originally for a mid 80's ford truck with dual tanks. Hopefully your bird has a return line. If it doesn't you'll need to run one.

Hopefully your bird was set up for a ecm controlled carb like alot of the vehicles in the era were, my monte was. If it was then you'll have the return line, and vss sensor. It would be a wise investment in a datalogging cable and cheap laptop to scan your ecm while your swapping the system, this will let you see what the ecm see's and take all of the guess work out of the swap. Check out the DIY prom board for even more juicy things you can do with your ecm.

BrightRed93Z28

Thanks for the responses! Yes, my 81 bird was installed with the engine controls. They were a little basic, but the SES light and all that is there. I don't have a laptop, but I DO have a POS old Compaq in the garage! I guess I'll just drive (or push, lol) the bird in the garage and do it the old fashioned way with a big ol' PC. I do have some other small questions though, since I'm already posting a topic. I have a set of Summit Racing Headers for a 305 in a 70-81 Firebird. Those will still work with the TBI setup right? I'm not doing any of the emissions crap, I'll edit all that junk out, so I shouldn't need the old headers with all the heat riser tubes and stuff should I? Also, will the LT1 cam give the 305 a nice lope? I'm goin to run straight headers to an X pipe and then to some mufflers, prolly flowmaster 40s. Will that sound pretty good? I've never really heard a 305 with exhaust, so I'm not sure what to expect. lol Any other mods that ya'll can think of?

odddoylerules

I am thinking of doing a similar swap on a 455 with a 454 truck tbi and ecu. where can I find info on the sensors required to make the tbi operational? BTW, The tbi system is seperate from the ignition timing controls, correct? I am currently using a gm HEI. will this be acceptable to use with a TBI swap?

Fast355

iTrader: (2)

Nope the ignition is integrated into the ECM.

Fast355

iTrader: (2)

The LT1 cam makes next to no lope in a 305, it is a very smooth idling cam. 305s with exhausts sound good, just like a 350 though. You instrument cluster will have a TBI compatible speed sensor in it.

1981TTA

I've just (mostly) completed a similar swap for my '81 Turbo TA. Depending on what you're swapping out (301T/301/305??) of your bird and what's coming with your buddy's 305, the list should be as follows :

To be used from your existing CCC setup :
- Coolant Sensor
- MAP sensor
- VSS sensor (this may need some modification)
- Distributor (or if you have a Pontiac engine and are swapping in a Chevy, use the computer controlled HEI distributor from the Chevy). This will have a 4 pin connector with no mechanical/vacuum advance hardware.
- TPS sensor connector. (I had to re-pin mine to get it to work correctly with the TBI.)
- EGR solenoid/wiring
- SES light

To be added :
- Wiring for Injectors
- Wiring for IAC
- Knock sensor / wiring for knock sensor. The sensor you'll need will depend on the ECM you choose. It will very likely be different from the one that's already on the vehicle.
- Fuel pump relay/ wiring
- Fuel pump
- ECM from a TBI application
- IAT/MAT sensor (depending on chosen ECM)
- Adapter plate to mount a TBI on a carb'd intake manifold unless the new 305 is alread a TBI setup.
- Fuel lines/adapters to go from TBI Saginaw fittings to whatever you're using to go to the tank.
- Under dash ALDL connector

I scrounged virtually all the additional connectors (Injectors/IAC/MAT/etc) and lots of harness wiring from various junkyards in the area.

As has been mentioned, you'll need a laptop and PROM modification hardware/software. Lots of choices can be found on the boards.

If you're going to use headers, you'll have to make accomodations for an O2 sensor. Another thing you might want to consider is modification for a heated O2 sensor while you're there.

I would be hesitant to use any of the existing return lines to the tank as a TBI return line. The existing lines are very small in diameter. This would likely cause problems getting the fuel back to the tank. I would (and am in the process of doing) run new return lines to the tank to be safe.

Depending on how you'll use the vehicle, there are a few choices of fuel pump / fuel tank routes you can go. Ideally, you'll want a fuel delivery system that is tolerant to gas sloshing around in the tank without killing the engine. Original FI vehicles have gas tanks that are baffled to make sure gas is always available to the pump. Some people resign themselves to using the non-FI tank as-is and keeping the fuel level above 1/4 tank at all times. Other options include adding a sump to the tank and using an external fuel pump or installing some sort of in-tank setup. You can take a look at Competition Engineering's sump kit here http://store.summitracing.com/defaul...2.asp&N=400079 . For this you'd just cut some holes in the tank and weld this to the bottom. Fuel feed/return ports are already there. For an example of an in-tank setup, take a look here http://www.chevythunder.com/fuel%20i...%20pg%20BB.htm and here http://www.tanksinc.com/index.cfm/pa...prod/prd84.htm . Keep in mind these are just examples. I'm sure there are other options/products around to do this.

That's about all I can think of off the top of my head. Let us know if you need help or have more questions.

1981TTA

Take a look at the wiring diagrams for a TBI ECM (like the 1227747) to see what sensors are needed. (Take a look here ftp://ftp.diy-efi.org/pub/gmecm/manuals/1227747/ )

The TBI ECM includes ignition control as well. The ECM gets engine speed/position information from the computer controlled HEI distributor. So, it becomes something of an all-or-nothing kind of deal regarding fuel and spark control. If you really don't want ignition timing controlled by an ECM, you might want to look at something like the Megasquirt system.

Fast355

iTrader: (2)

I used my existing 5/16 return line for months without a problem. I used a ford truck frame mounted fuel pump. Van fuel lines have connections right at the rear of the engine on the frame. A FF508 used for a 2.8 TBI S10 has a hose fitting barb on it. The other end screws straight onto the van fuel lines. The other end gets connected to the original van fuel line. My stock carbed tank was baffeled and had a booster pump in it similar to the LG4 camaro.

odddoylerules

Can a gm HEI be modified to work with the computer? the engine is an oldsmobile, so I am not sure how I would make a chevy distributor work.

dimented24x7

iTrader: (2)

I dont know the details but its been done before. Search maybe?

RBob

iTrader: (1)

A lot of 307 Y motors came with the CCC setup. The distributors are large cap ECM controlled. Have no idea if they will fit the 455, but if they do. . . Or if the guts swap into the 455 distributor.

RBob.

1981TTA

About half way down, there's discussion of how a non-computer controlled Pontiac distributor was modified for ECM control. You might be able to do something similar with the Olds.

https://www.thirdgen.org/techbb2/sho...hreadid=309530