Converting older trucks to TBI

[Tommyd11730]

Ok, I'll admit it, I'm getting old.  Love me 91 K5 5.7 TBI setup.  Yes it's bone stock and only sees pavment.

So here is the thing.  I have a 1984 GMC 2500 4x4.  Also bone stock with 5.7 and 700R4.  Kicking around the idea of removing the carb, air pump, tubes, emissions, and fuel pump.  Then adding a TBI setup similar to the one on my K5.

I see "kits" for sale in the $900 range.  Just wondering people's thoughts on such a conversation.

Thanks

[jbrow1]

I eventually plan to do this with my 1980 k10.  It's got a 250 in it at the moment, once I get a 350 in it, I'll be looking for some kits.  Summit had some very reasonable kits, that looked easy to set up, and they then learned themselves as you drove.  I was kind of interested in what exactly they were learning (programming) themselves for?  The type of driving you do, or more the environmental factors like humidity/temps, etc.?  I've also simply been looking for the right 1987 whatever that would already have everything I want.. FI, pump, motor/trans, and all that. 

[Irish_Alley]

i see others paying good money for their setups. me i would much rather go to a junkyard and get the crap off that vehicle. but that 700r4 would need the tv bracket off the tbi. im not sure if theyre the same or not maybe someone could verify or you might have to do a visual

[Tommyd11730]

Agreed, if I convert I'm sticking all GM, like what's on my K5.  Funny side note, the fuel pump on my pickup just puked today!  Looks like it's going to be fun to change with that air pump in the way!

[Stewart G Griffin]

As much as i'm into being cheap and easy----(carbs), i really like the TBI system and i find myself leaning that way.   It's really a good system and if you think about it, fuel injection is actually simpler than carbs.    My other car has TBI and has gone 340,000 miles no problems (ok, well recently i think the pump may have gone out, but i think that was due to sitting for a while and besides---340,000 miles!)

Those new fuel pump sumps are going to make EFI conversions even easier.

i would lean towards buying a complete kit, such as the ones offered by howell:
http://howellefi.com/

As opposed to trying to find all the parts from a salvage yard.  Now, if you CAN find all the parts in a junk yard then fine, but when you go with a complete kit all the parts are new or remanufactured (which is as good as new).

i am also open to just buying a pre-existing and running 4.3 truck with TBI.

[Captkaos]

I would do it in a heartbeat, but I would get all the hard parts (intake, TBI, distributor, etc) from a donor.  I would get a stand alone harness from one of many wiring companies if you don't trust the donor harness.  Just make sure you don't  have some radical cam in it...

[werewolfx13]

I swapped the engine, harness, ecm, and fuel tank from an 87 v20 into my 76 k20. Not a terribly difficult swap, but it would be ideal if you had the donor nearby to pull parts off as you figure out what you need. In my case, I pulled what I thought I needed in a hurry, but missed a few things that would have been nice to have, like the steering column and instrument cluster, and the donor was already scrapped. The conversion from a TH350/np203 to an sm465/np205 was much more work.

[SkinnyG]

You CAN tune with a radical cam, but you need an ECU that will let you tune Alpha-N instead of Speed Density.

Speed Density uses a MAP sensor (engine vacuum) to determine engine load.  Typical engine vacuum is about 18inHg at idle.

Alpha-N uses Throttle Position to determine load.  Typically, more throttle = more fuel.  My engine idles at 8inHg at idle - Speed Density would think I'm at half throttle or more.

If your engine is mainly stock, and intends to stay mainly stock (or mild ecu-friendly cam maximum), Speed Density (the most common) will do you fine.  If you plan to build up more of a hot rod engine, you may want to look into an ECU that can tune Alpha-N.

I spend two years trying to get Independent Throttle Bodies working on Speed Density.  You open the throttles even a little bit, and you lose all your vacuum.  crusie manifold pressure and full throttle manifold pressure were so close, the ECU couldn't tell them apart.  Alpha-N was the win.

I have all the parts to convert my '77 to TBI, and intend to do so this winter.

[roundhouse]

I've done it
I bought all theTBI stuff from a running 305 with a cracked block
For $200



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[VileZambonie]

I bought 3 Suburbans for a total of $200 bucks. Two of them were TBI 350's, one was 4X4 one was 2WD with a 4L80E and the other was 2WD with a 454/4L80E. They make great donors for these trucks including the TBI system.