whos done the TBI conversion? thoughts

[davidh]

I just want some after thoughts of ppl that have done it. any regrets or tips? what did you do for throttle cable? Lokar? Anyone keep their stock gas tank? If so where and what electric fuel pump did you use.? Where did you mount the computer?

My plan is to rebuild the short wheel base frame I got today put in the TBI/700r from my donor 88 truck then set my 68 cab/clip on it.

[ND_guy]

I did a tbi swap over the holidays and I love it. I had some drivability issues initially, but it runs fantastic now(Was a bad vacuum leak).
I Pulled the 400 out and swapped in the 305tbi. I will be able to get some pics tomorow.
The computer is in a 30cal. Ammo can on the fire wall by the brake booster. I used a stock in cab tank. I had to plum a low preasure pump to feed a external fuel reservoir with a high pressure pump in it. The high pressure pump in the reservoir feeds the throttle body.

The wiring harness took the longest to adapt I have quite a few hours tied up in research and modifing it.

I am getting a digi cam tomorow then I will post up.

[davidh]

thanks sounds great. Look forward to that.

[svgould]

I performed this swap.....best thing I've ever done. I love it. I used the Lokar throttle cable, walbro inline external pump, and original gas tank. I just a sending unit from 1972 truck....it has two line going into the top. I extended the one line into the tank and used it as my return.

Shane

[Ol'Rover]

I will be performing a swap! i thought i was the only person with this idea lol thank you for bringing this up! Sounds like its a realitivly easy swap to me.

TBI 305 700R4 into 71 c10 alriiight!

[clay68c10]

Did it last year on my 454, love it! Used the original tank with a return in the sender, inline fuel pump under the cab. I used a mechanical throttle linkage from here: http://www.bakerprecision.com/longacr53.htm
The ECU is under the dash just above my e-brake handle. The harness took some time to modify and loom up, but wasn't hard at all. I used a 7 circuit add on fuse panel from Painless to run all my power so I could leave the stock fuse box alone.
If you have a whole donor truck, grab the 5 lug voltage buss off the firewall and use it instead of the crappy 1 lug that these trucks came with. Then you're ready for other upgrades like relay headlights and bigger alternators...

[mtndewmaniac66]

I have a Holley 502-20s TBI conversion kit still sitting at home in a box. I have a rebuilt 327 with an output of (estimated) 350+HP. Apparently, it will not support any engine over 275HP due to its design. Even if the injectors were to be replaced with a higher flow design, its limiting factor would still be the limited airflow/fuel supply. (at least that is what the tech at Holley had replied) But I will still play with the system to see if I can get it perform at a higher output.
(Holleys projection unit is supposedly a direct replacement for the stock TBI unit)
I would love to perform an EFI conversion, but I still need more info for what will work for my engine.

[GlennBrittain]

I have a donor 89 GMC, that I plan on useing the motor for a rebuild with the TBI. I have been researching what I can and can not do with the TBI on the internet. Some of the sites I found was discouraging while others said the TBI was good and would work with a 30% engine upgrade. I would like to know if anyone has a TBI system working on a mild 383.

[ND_guy]

Just got my camera today will post up pics this weekend after I figure out how to use it.

[franky69c10]

i plan on doing this also,i have a 87 chevy TBI with a 700R4, i just dont know about all the wire's and if its gonna be hard.....

[qksilver]

I am in the process of doing this swap myself. I have everything figured out but the wiring harness and computer.
What have you guys done?
This would help everybody...............

[svgould]

Originally Posted by qksilver

I am in the process of doing this swap myself. I have everything figured out but the wiring harness and computer.
What have you guys done?
This would help everybody...............

I just hacked the harness from the donar vehicle......it took some time, but wasn't that bad.

Shane

[Blue_71]

gonna sound like a broken record here, but i did the swap on my K20 last january. mounted the ECM beside the brake booster, and spliced in a harness from a 87 C10. the harness was a pain, but otherwise its an easy swap.

[BarryB]

I am pretty sure you can get a wiring harnesses for such swaps from such places as painless wiring. I know there are others out there but their name is what rings a bell.

[HavinSomeFun]

I think the harness is $300 already set up. You can get the computer programmed for whatever setup you want. I was told you need a computer with 747 in the number...

[mtndewmaniac66]

Originally Posted by BarryB

I am pretty sure you can get a wiring harnesses for such swaps from such places as painless wiring. I know there are others out there but their name is what rings a bell.

The other name that comes to mind is EZ Wiring, Summit Racing sells this brand along with Painless wiring.

If some one is performing this swap, it would be best if you happen to pull all of the wiring harness from the donor vehicle, like svgould stated, and keep a Haynes or Chiltons manual handy for cross referencing. It is also wise to look over BOTH wiring harnesses AND schematics before hand and take down notes onto paper, this alone significantly reduces installation time and confusion.

And yes, the benefits of reliability and economy are well worth it.

[mtndewmaniac66]

I forgot to mention this, my involvement was when I was asked to help out a friend, who ended up just stepping back and allowing me to complete the swap. This was also done in a carbureted '85 Trans-Am, but still within the same field.

[Scott68-93-97]

Go to http://www.tbichips.com the guy has all kinds of good info on tbi systems and he sells and re-pops the cpu's for performance he can get you a good 330hp off tbi even more if you bore or step up to a bigger throttle body he even has a setup for a 383

[ND_guy]

Here are the pics of my TBI setup. I haven’t put wire loom on yet I am leaving them unwrapped until I get a few more miles on it and get it in a heated shop. It has been below zero for about two weeks and working with wiring isn’t any fun when you can’t feel your fingers.

Was the project worth it? Definitely! I started this fall when my roommate’s father who owns a small scrap business was getting ready to crush some cars. He told us to come out and get what we wanted before it went on the “Iron Boat to China”. I pulled a complete 88 TBI setup off a 1/2ton 350 with a 1227747 computer. My initial intention was to put it on the 400sb in my 67, but that got pulled for a 72 Nova project. I put the rebuilt 305 back in the 67 and started the TBI swap.

The wiring took quite a bit of time. I am still not done with the wire loom but I have put on three hundred trouble free miles so far.

-EGR wiring is still in the harness in case I change to newer heads in the future.
-VSS is not connected(only needed if you have EGR)
-Cruise, AC and Air pump wiring removed
-P/N switch grounded
-Pulled all the instrument cluster wiring out(water temp, oil press, shift indicator, etc)
-Wired all the switched 12v sources through a 40amp relay(didn’t trust the 41 year old ign. switch to provide enough amperage without excessive voltage drop)
-Added extra ground straps to the engine.

The intake manifold center bolt holes had to be enlarged to fit on my 84 305 heads.

I tried to save money on the fuel pumps and it ended up costing me more money. I had a brand new in tank pump for a 2000 S10 in the garage and I mounted it inside that pipe reservoir on the fender. It is fed by a low pressure electric pump by the tank. I am not going to give more details so you aren’t tempted to try it.

I recommend doing a Blazer tank swap and use a TBI in tank pump, or get a Carter p5001 and mount it by your factory tank. It will save you the mess and hassle I have. I will change to a Blazer tank eventually, but I am a student with too much invested in this setup to change right now.

To plumb in the TBI I used:
-14mm o-ring to AN-6 power steering adapter for the return side
-16mm o-ring to AN-6 power steering adapter for the pressure side
Once you have them adapted to An-6 you can use any hose or barbed fitting you want.
I ran 3/8 inch hose in and out of the TBI

I used a new O2 sensor, knock sensor and CTS sensor.
Base timing to 6 degrees BTDC instead of zero because I don’t have new swirl port heads(I have crappy 601 heads).

The cammed 400sb with the Q-jet got an average of 9.1mpg. The 305 TBI just pulled down 14.3mpg going 60mph and 12.1mpg going 65mph.(All highway no warm up)
I usually drive 60 the 4.56 gears really make that small block scream.

THAT IS A 57% INCREASE IN FUEL MILEAGE!!!!!!!

I am definitely down on power from the 400, but this engine is so smooth with TBI. At this point in my life I am willing to sacrifice power for MPGs. I couldn’t afford to drive it at 9MPG now I can.

If I could only figure out how to save 57% on the $625 I spent on text books this semester.

THE WIRES ARE GETTING LOOM JUST NOT YET.

The Bad choice fuel delivery system

Here you can see my throttle rod adapter



The waterproof computer box

The victim

[qksilver]

So basically you get a wiring diagram keep what is need for the engine and disconnect everything else, tell who ever burns your chip the engine details and what you have deleted.
Keep the original harness of the truck the engine is being swapped into. Get tee's or what ever needed to mount the senders for the old style gauges.
I have the time and many TBI wiring harness ecm but not the $300 to spend just for a harness.
Cool, thanks for the info

[clay68c10]

I went from 8mpg to 11mpg (in big-city traffic) and the drivability is so much better. If you're handy with wiring, you can do the harness yourself. I also left my harness un-loomed for a couple hundred miles just to work out the bugs/routing. It's all taped up now and it was easy to hide most of it at the rear of the eng so it looks clean.
I haven't gotten a chip made yet, but I'm sure it will run even better when I do. I got the free WIN-ALDL software so I can log data and send it to the TBI Chip guy. This is also helpful if you want to peek in at what the ECU is doing or check for malfunction codes.
I'll second the idea of getting a wiring diagram, it would have been a huge pain to deal with the harness without it.

[svgould]

Instead of having somebody burn you a chip.....do it yourself. All the equipment can be had for ~$100....having somebody burn you a chip will cost almost that much. Go check out the thirdgen.org forum....pretty good bunch of guys and they have a section dedicated just to tbi......granted it is most camaro stuff but the concepts are the same.

[ddpaxman]

I am considering a TBI swap on my 71 Blazer! I have found some good information here http://www.rowand.net/Shop/Tech/GMTBISwap.htm

But I can't seem to find the all important wiring diagram for the ECM that will sow mi what wires I need and what wires I don't. Does one have one? Can I use a repair manual to get the wires I need?

I am terrified that I will not be able to hook the TBI back up after I take the pieces from a junk yard.

[sneakysnake]

Here is some info I have saved back.
http://www.automedia.com/TBI_Fuel_In...ht20001001fi/1

[1969stepside]

here is a link to a tpi site for the conversion if this helps




http://www.aztpi.com/home.php?xid=bd...fa036d5a83fc1c