So after much debating and thinking, I've decided to swap to a single TBI unit. The swap seems straight forward. Remove old intake, add new. I'm thinking of getting an edelbrock performer TBI intake and using a 454 TBI, however I heard that the 454 doesn't have a TV cable provision so I may stick with a 350 and bore it out. Does this seem plausible? Also, can I use my current crossfire injectors in my new TB? From what I understand, changing the injectors, throws off the Computer tuning, however I'm uncertain if the injectors will fit or are capable of supporting the 350 or 454 TBI

 

Prob get better answers over here

http://www.thirdgen.org/techboard/tbi/

 

I did that swap about 10yrs ago, you can use the tbi unit for 87-89 chevy 350 trucks, get one at a junkyard & do the ultimate tbi mods. I went w/ the holley tbi (same appilcation), used their tbi intake too. It comes w/ throttle brackets & other hardware. The eddy intake is barely better then stock, it has those different inake bolts in the middle.. Or use a 4bbl. intake w/ a tbi adapter. All the wiring will work w/ that tbi & the ecm will run it, if you change the cam use one that makes good vacuum for the map sensor.

 

Power wise I doubt you will see much, the really only positive thing is a faster ECM. For all the trouble why not just go TPI? That takes no more electrical work to install and you will have a much better power and torque advantage.

I did the 7747 ecm swap on my 82 vette many years ago as well as a thermostatically controlled electric fan swap and keep operating temps at around 205 degrees and my CFI responds much better.

 

"Much better" than what? The ECM you swap that you did nothing for "speed" as it has been proven to be no faster than the stock unit. And MY CFI ran 170-180 with a 160 stat and a Taurus electric fan...and it responded much better than stock to that too. Proven with objective data at the drag track.

To the OP; I think doing the Single TBI mod is the right way to go (vs. the recommendation above to use costly-AND-gutless-TPI); it offers way more options and performance at a much lower cost, than a "TPI" looking system will. I would definitely go with the TB>4bbl adaptor route as opposed to the "Performer TBI" intake, b/c the former give you nearly unlimited options. The latter, you have just the one barely better than stock option and that is it.

454 TBI: All of the 454 TBI's that we used to have at work had TV cables. I don't think that TB will do anything for max power on a stockish motor based on my observations going to 2" bores on stock CFI TB's on stockish CFI motors, other than skew the throttle results lower down in the range of travel. In other words, the throttle will become more responsive off idle, and 3/4 to full throttle will likely do little to nothing.

The ECM doesn't know or care what injectors it's driving -as long as they're GM TBI injectors. The way they "calibration" gets "thrown off", is that since the injectors are way larger in the 454 TBI (~75pph compared to ~55pph), and the ECM doesn't "know" that, then on a stock or stickish long block, the thing would run WAY too rich. I would definitely start out with stock CFI injectors, or stock TPI 350 injectors and adjust as necessary from there.

All GM TBI injectors are identical on the outside, and are interchangeable, from the "Iron Duke"/2.5L to the 2.8L TBI v6 all the way up to the TBI 454. Same same. Only difference is the orifice size in the injector that regulates how much fuel escapes when the injector fires...and that can be used by you, as a tuning tool.

-Tom

 

So the 87-89 truck TBI is much better than the CFI? Is that true on a stock engine? Do you have to swap the ECM? Are there any wiring issues? Is it a difficult task or can just about anybody do it? I have a CFI and am curious about this also.

 

If you put a 2bbl. tbi on a crossfire intake it would perform about them same, the advantage is in the intake you choose. You'll see why when you take off the crossfire intake.
You can use the stock wiring & ecm to run the tbi, the only thing extra is a iac connector that is unused. I'd get an adjustable fuel press regulator for that tbi unit.
As far as how difficult it is, if you have swapped intakes on 350s before you should be ok.

 

This sounds really great! Will the tbi fit on the later stock 350 truck vortec heads? I guess with using the tbi, there would be no hood clearance problems?

 

You can get a tbi vortec intake but they are pricey, might get a used one on the internet. Or you can run a vortec carb intake w/ a tbi adaptor. You'll have to get creative with the air cleaner, I used a 2" open element air cleaner but I've seen guys used those filter hats(Spectre makes them) with cone filters. An intake with a slight angle at the carb mount will help clearence. Cafefully measure your hood clearence before you slam the hood. The fuel lines that screw into the tbi fittings have a special flare w/ an o-ring, you can get these at the parts store under the Dorman fuel line repair kits. The tbi runs at the same fuel pressure so your stock fuel pump will work, & your fuel filter will be ok too. You can reuse you stock hei too.
The only trouble I had was with the air pump bracket, on the original intake there is a bolt hole for the bracket, the intake I put on it didn't have that hole. No biggie if you get rid of the air pump & run an 85" belt.

 

My bad. I was thinking the 87-89 tbi truck intakes were vortec. I am still interested in going tbi as you were advising and I am trying to go the most economical route for a little more power for the buck. That's why I was asking about the vortec heads. I am thinking about somewhere around 300hp or a little less with extra torque. I really appreciate the great information.

 

I disagree. The larger the intake runners, the more possible power. So as long as I get a higher flowing intake, I'll have more power. As to the fans, 84 model is controlled by a temp switch and I prefer to keep mine below 185 so I can advance the timing.

What's a good 4 barrel carb intake to use with the adapter?

 

You can accomplish that goal w/out swappping to a differnt intake system. Thoroughly porting the stock CFI intake will put you in a position to reach your power goals, air flow wise. After that most other changes will be the same as you'd need to do to any mid '80's Vette.

 

What's the rest of your combo? What are your goals?

 

Thanks Tom. Looks like I am going to give porting a good try and start looking for reasonable priced heads if there are such a thing. I really appreciate the information and also want to thank the OP for starting the thread.

 

Well I picked up an entire intake out of a 90 350 truck for $85. It will take some adapting to get the throttle lines to hook up. I plan on getting a 4 barrel intake still tho. But for now the TBI intake seems to be a better option already because the intake runners are bigger.

My goals are 300 BHP and so far I have 1.6 Rockers.

Also, a 1990 K1500 has the same TPS as my 84 Vette. The TPS is different in 91. However, the 4 inner bolts are straight not angled.... Not sure what to do

 

I have run the 2 barrel TB unit now for a few years. With the stock ECU the IAC settings will be off as the CF uses 2. Your resulting idle will be off as in too low but there is a work around for that. Other obstacles to overcome.

Holley projection tbi manifold

[IMG][/IMG]

 

Well I got the intake in. Took a lot of grinding so that the bolts would go in at the correct angle. Now if what you're saying is true about the IAC, how do I fix it?

 

Ok heres what I did, I know its kinda ghetto. I got a iac & housing off of an 85-87 camaro 2.8L, cut the excess down & tucked it into the harness. It idles good.

 

I'm not seeing how the IAC would be a problem? I mean yeah, crossfire has two, but they run on the same wires. Plus, you have a base idle already.

Thought I'd go ahead and share what's been done. So I picked up a 1990 K1500 TBI intake from a local junkyard. Removed the old intake and sat the new one in to find that in 87, center intake bolts on the heads were changed to a more straight angle. So I took it back off, and with a drill bit, bore the hole to the correct angle. Then I put the intake back on and tightened it down. Afterwards I hooked everything up to find out that i broke the in-fuel line on the injector pod. So I'm waiting on a new throttle body as we speak. As for the air pump problem, I had already remove it and ran a shorter belt, so no worries there. And for the air filter, I have about an extra 3-4" of clearance because there is a hole in my hood underneath my hoodscoop for fresh air. Anyone want a crossfire intake?

 

If its free, I would come and get it.