where to start with GM TBI conversion? (1 Viewer)

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what intake manifold do i use? can people just tap into the regular carb manifold and install the sensors in there appr. places? (edelbrock manifold) From what i've heard either the manifolds from carb to TBI's bolt holes don't line up or the angle is different on the heads... so what do i do? do i need some specialty intake manifold? I know summit sells adapter plates for this type of situation so what do you do with the sensors that need to be in the intake manifold?


whats the best vehicle to get the stuff off of? 88-9X truck/van/or suv???

I have a general understanding of TBI now that i spent a good deal of time studying a fuel injection book at the local book store...
 
Edelbrock might make a manifold but I dont think so... A TBI manifold sits just fine on a pre 86 block, you just have to hog out the holes because the angle of the bolt is different. your better off getting TBI heads that bolt right to the short block... I wouldn't waste my time with TBI but rather get an LT1 or vortec or newer engine

TBI is great but sooner or later your gonna want more power & TBI is not the way to do it.
 
my tbi 350 pushes my heavy ass 55 on 38's around the trails well IMO... and is easy to diagnose with the SES light.. add an inline fuel pressure guage and carry a spare pump... no issues on angles and the power is sufficient.
 
adapter

You could use your original intake and just put an adapter on it for the TBI . It might make it sit a little higher but only about 3/4" .The rest of the ports that you need you should be able to find or adapt.I haven't done it this way but I've built a couple of tbi setups from scratch for 2F's. The only other thing is the knock sensor and you can use the fuel pump block off plate for it if you want.You just have to tap it out to the correct npt size. You will also need to change the dizzy or you could modify the original one to a 7 pin module for the dist. hookup to the ecm ., When you find the donor make sure you get everything you need or think you might need .The esc box and the knock sensor are more important than you might think they control all of the timing advance.The wiring harness isnt that bad either if you wanted to build your own one . remove the looming, hook up all the sensors ;dist.,fuel pump and relay and the rest is pretty easy .Pink/Black -switched pwr ,Orange -to the + side of the Batt. and some grounds - Blk/wht , tan/blk or blk there are some variations but that should make it run . Also make sure you use metal filters for fuel they should be for Fuel injection.I always put at least one in front and one behind the pump when they are inline.hope this wasn't too much info and helps you out a bit.
 
Good post, I ran in Ables truck...... the thing was darn neer rolling over in a puddle and it purred like a kitten.

Kid knows how to wheel his junk...




too tall said:
You could use your original intake and just put an adapter on it for the TBI . It might make it sit a little higher but only about 3/4" .The rest of the ports that you need you should be able to find or adapt.I haven't done it this way but I've built a couple of tbi setups from scratch for 2F's. The only other thing is the knock sensor and you can use the fuel pump block off plate for it if you want.You just have to tap it out to the correct npt size. You will also need to change the dizzy or you could modify the original one to a 7 pin module for the dist. hookup to the ecm ., When you find the donor make sure you get everything you need or think you might need .The esc box and the knock sensor are more important than you might think they control all of the timing advance.The wiring harness isnt that bad either if you wanted to build your own one . remove the looming, hook up all the sensors ;dist.,fuel pump and relay and the rest is pretty easy .Pink/Black -switched pwr ,Orange -to the + side of the Batt. and some grounds - Blk/wht , tan/blk or blk there are some variations but that should make it run . Also make sure you use metal filters for fuel they should be for Fuel injection.I always put at least one in front and one behind the pump when they are inline.hope this wasn't too much info and helps you out a bit.
Click to expand...
 
bandy rooster said:
what intake manifold do i use? can people just tap into the regular carb manifold and install the sensors in there appr. places? (edelbrock manifold) From what i've heard either the manifolds from carb to TBI's bolt holes don't line up or the angle is different on the heads... so what do i do?..
Click to expand...

The easiest solution is to use the stock TBI manifold on your current heads. The only bolts which are different are the inner four. The TBI manifold is drilled at a steeper angle. What you need to do is slot the holes a bit and it will work. The intake is aluminum, and all you need to make this a 5-minute job is a cutter bit on a dremel.

I converted my 1977 350 this way. I have no leaks whatsoever around the elongated intake holes. I cut the holes slowly, re-fitting the intake to the heads after removing a small bit of material until the bolt holes in the heads lined up with the intake. Use the TBI application intake gaskets when you reassemble.

BTW, I am using a mild gring comp cams camshaft, and had my heads lightly reworked - 305 intake valves (bigger) and some bowl work to increase burn efficiency. I also run stock TBI exhaust manifolds. My #1 factor was reliability, and wanted to use mostly stock replacement parts for ease of repair (if ever needed).

I think the stock TBI intake is a good unit, if you don't plan on a whole lot of mods. It does have flow issues with high-rpm motors. But who drives a 4x4 with high rpms, maybe mudders... It works great with mine. GM designed this intake with the TBI in mind. This makes me believe it would be better than converting a carb intake to use the TBI.

To tune I use WINALDL with a cable that connects to the ALDL. I have adjusted my fuel pressure to 17.5 psi, and run a custom chip from Custom TBI chips. I have great throttle response, and can run mid-grade, or blend it with the 85 octane stuff here in Montana without any knock problems. The reason I had to tune is because the '77 motor with the cam, valves, and slightly higher compression. It ran OK with the stock chip, but after I got the custom chip and fuel pressure, it was like "WOW" what a difference.

I still get around 12-13 mpg (4.88 gears and 36" tires).
 
My preference for the harness is to use a GM harness. The wire quality is second to none. Yes, its better than Painful's. Careful prep is key. Label wires as they are removed.

Only 3 or 4 will go to the firewall bulk head. Those wires will be 1. ignition power (12v), 2. timing wire (tan w/white stripe - has a connector to disconnect to set timing), 3. fuel pump power, 4. fuel level sender signal.

The rest of the engine harness will go directly to the computer.

If you don't run AC, find the dark green wire that goes to pin B8 (assuming your using a 7747 computer). Hook it to a switch that has 12v power and it will idle the engine up 50-200 rpms when turned to "on". This is good for winching etc. That circuit is the AC sensing circuit. I did this with mine and does work. I think the chip could be modified to increase the idle even more, but the guy who burned my chip didn't know how...
 
I'm running a 92 setup on a 96 vortec rollerblock with vortec heads. I run a stock gm harness, it is great, just get the hole thing .Clean it up get a big table and a contnuity tester and label, label, label. Go to TBI chips.com and read some of his pages. He burned my chip for me and did a bang up job right out of the box. He has since burned me some new chips after datalogging. I love my setup, will run on its lid.
 
76 PTO said:
I'm running a 92 setup on a 96 vortec rollerblock with vortec heads. I run a stock gm harness, it is great, just get the hole thing .Clean it up get a big table and a contnuity tester and label, label, label. Go to TBI chips.com and read some of his pages. He burned my chip for me and did a bang up job right out of the box. He has since burned me some new chips after datalogging. I love my setup, will run on its lid.
Click to expand...

I'll second that vote for www.tbichips.com. Brian is a genius and his service is second to none. Your current manifold is better that the stock TBI manifold, so are your heads. Buy or make an adapter for the throttle body. I made two, they don't look like much, but I would be happy to send you one free of charge, just send it back if you don't use it, PM me if you want it. I used a stock harness form an '89 suburban, it is very good quality stuff to start with, it has aged well, I had no issues. If you are making (or planning on making) more than 250 horse, the stock TB from a 350 will be too small; they only flow 450 CFM. The options are get one from a 454 (750 CFM) or get a 350 TB rebuilt and bored to a larger size. I wenty to 47mm (up from 42mm) that will flow 600 CFM. I used RV Morse machine in CA, there is a link on TBI chips' website.
 
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Since you are converting to EFI anyways why not a TPI system.
There are lots of units on Ebay with plenty of aftermarket support.
Can go MAF or MAP, more power than TBI.
 
I used these guys for the TPI install into my PU.
Picked up his MAP harness, & computer w/chip for $375.oo
He carries harnesses for TBIs as well.
http://www.larryselectricsite.com/
 
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