Converting to TBI .

[f.monroe]

Does it help any with gas mileage and has anyone done it using the existing intake ? I have a chance to pick up a 91 Suburban and the only thing I want is the fuel inj. if it isnt a hard swap . The truck is a 4 wheel drive with the latermodel front clip and descent interior so I am sure I could part it for what I can get it for making the injection free . Seems like it would be easy . Anyone on here done it and have any insight into the job . Frank

[krue]

Here's a link someone posted today.
http://www.automedia.com/TBI_Fuel_In...ht20001001fi/1

[Srubydo1986]

youll need the heads and intake. along with the tbi and wire in and computer. but its easier just tto use the hole block cause the cam is deffent from that of a carberated.

[krue]

You don't have to have the heads, you can even buy an adaptor and use a carburetor intake.

[Mickey_D]

But you will need to drop the tank and put the injector's fuel pump in....

[MylilBowTie]

If its a stock cam there isnt any need for a change either. Starting out I would stay stock. Then I would get into tuning the ecm and data logging. To get a feel for what its like and twist a little more fuel mileage. Its much easier to start out stock then get better upgrades.

Just in what I have noticed car tbi engine are more likely to have roller cams vs trucks in the early years. I seen 87 91 93 truck tbi engines all had flat tappet cams.

My 92 Camaro has a lo3 tbi 305, I just got 25.8 mpg on the highway @ 70.

[Captkaos]

My 87 R10 with 305 TBI got almost 22mpg on the last trip I took to Maggie Valley.
Why not use the complete motor?

[Russell]

I think you'd be best off switching the whole engine over. The TBI engines run higher compression, different cams and are calibrated for as much. It will run reasonably well on a stock engine, but it will always have a bit of a surge at idle, and a tendancy to perform a bit poorly at lower RPMs

[gotit]

I switched my 86 to tbi, with a 89 stuff. it was not that hard to do. i need one of those engines that your not gonna use!

[rfmaster]

Converted my 75 C20 from Carb to TBI and never looked back. Short video on youtube.

http://www.youtube.com/watch?v=sfxuOOliRdg

For a near stock 350 a lot more throttle response, much smoother idle, etc etc. Factory chips for SD based systems work well on stock to mild engines. Even though TBI can be adapted for wilder cam, but that takes time tuning and burning your own chips.

Still plenty of work ahead:
In cab wiring harness (you saw that mess didn't you??)
P/N switch mod
TCC mod
TV cable check

[navybear70]

I just stripped my TBI out of my '87. The "rebuild" motor that was purchased, three owners ago, for the truck is not TBI ready I don't think.

[Russell]

Looks almost like it belongs eh?

If I was to do the swap again, I'd delete the EGR valve stuff, and put both the MAP sensor and fuel pump relay on the other side of the firewall so I didn't have any clutter.

Fuel system was a saddle tank sending unit from a 90 crewcab with a TBI pump, and a set of stock 89 TBI stainless braided steel lines. They were practically the perfect length to reach the factory saddle tank with the new sending unit, just needed about a foot of EFI pressure rated fuel line to go from the sending unit down to the frame. Took me an afternoon to run the fuel system.

Electrical was nice and easy, took me an evening using the stock 89 wiring harness, then adding half a dozen new wires to the stock 77 harness, no major modifications required. I simply wired the park neutral wires for the starter together, and used the switch for the ECM, check engine light I tied into the factory idiot light on the right behind the speedo, and installed a Service Engine Soon lense from the 90 crewcab's cluster.

Swapping the actual intake over was another afternoon, she fired almost immediately, and ran pretty nicely

Unfortunately, didn't seal the rear of the intake properly, and it leaked oil like a seive. It ran reasonably nice once I started driving it, but I had some issues with the stock timing curve on the prom, the engine always wanted way more timing, but if I advanced the distributor to where it ran good in the top end, the idle quality really suffered. If I set it so it'd idle perfect, then it really became lethargic in the top end.

I was daily driving the truck as I did the swap, and didn't suffer any unexpected downtime, took me three weekends, while driving the truck every day during the week. I'd swapped in a 700r4 prior to doing the TBI swap, and just used the old style TCC stuff I'd put in from an 84 - 86ish truck instead of using the TBI ECM. It averaged 17 - 19 mpg on the freeway in 3rd gear at 65 mph. I regretted the 700r4 swap due to the 3.08 gears, really made it kinda useless. If it had 3.73s or 4.10s, then overdrive would have been more useful, lol

As far as I know, it is still be driven like this today, I sold it to a forum member earlier this year.

[beaterC10]

Russell,

Did you mount the stock ECM in the dash? I have considered installing TBI on my 86, but putting the ECM in the stock location looks like I would need to replace the 86 dash harness with the 87 which would mean tearing apart the entire dash.

[Russell]

I actually bought some 1.5" wide industrial strength velcro, then stuck two pieces to the back of the ECM, and two peices on the air box just above the tranny hump. It held it there extremely well, and gave great access to the prom chip.

Here is a pic where you can see the ECM hanging out When you were sitting in the truck, you couldn't see very much of the ECM, this camera angle makes it look like it sticks out way further than it did.

TPI ECMs sit in the same spot very nicely too

[Captkaos]

If you have the CCC or ECS, you can also mount the ECM in its spot. That is where I am putting it on my TPI Vette.

[watahyahknow]

on my old opel GSi the brain was mounted above the glovecompartment you had to get the inside of the box out to get to it under the top of the dash or against the firewall.
it might be too hot a place under steel and in the american sun another place they put it in european cars is inside the kickerpannel on the passenger side or next to the passenger seat

[f.monroe]

Thanks for the info . I have been working a lot lately and havent had a chance to call the guy and tell him I would take it . I am going to try tomorrow . I will let yall know if I pick it up . The only reason I wanted to know about using this on my stock 77 engine is because it runs soo good . Well , all except for me having to disassemble the carb yesterday because it developed a nasty vibration and miss under 1000 rpm last weekend . I determined it was in the carb and found one passage clogged . I cleaned it and reassembled . Smooth as can be again . The truck doesnt get driven enough and the carb dries out ,I guess , leaving some residue that built up . I never really thought about a total engine swap but I have a GM reman 700r4 from a 2wd sub and this one has the computer for a 700r4 . It is 4wd but I wouldnt think it would be very different .
Frank

[gchemist]

Everything you need to know!!
http://www.california.com/~eagle/howell.html

[Russell]

The 4x4 vs 2wd doesn't make any difference in the ECM, it doesn't know or care if it is in 4x4 or not. The newer PCMs that control transmissions to need to know if it is in 4lo so it can shift the transmission different, but yeah, older setups don't care either way.

That 700r4 should work nicely too, good chance it will be a direct replacement for your current TH350 (at least it was with my 77). Make sure you look into getting lower gearing though, at least 3.73

Swapping an engine out is no big deal, but if that one is as good as it sounds, I'd just put in a TBI friendly aftermarket cam, and get an adapter plate for the carb intake