What style fuel injection to use

[luvbowties]

Been pondering converting my carb'd, 1996-1998(?) stock 5.7 Vortec with headers to fuel injection. My truck is a 1966. [I've got in storage a complete tbi system from like a 1989-1990(?) pickup with 5.7 engine--all sensors, wiring harness, & computer. Guess I'd have to call it a 2-bbl f-i unit.]

Anybody converted a stock 350 to fuel inj. and been happy with it? Also, another question is what does it do to power and useable torque range? Present power is really good for what it is, and it starts & performs flawlessly, cold and hot. MPG is about what they all do when set up with carb & headers: 11.5 to 14.5. Expect a long I'state run would do better than those numbers, as I have a 700R4 and 3.73 gear, and have the lockup functioning superbly.

I like the simplicity & clean look of the newer all-in-one units that include the tps, temp sensor, and other sensors built into the tb-unit. I also like the self-tuning capability of some systems, as I do not care to design my own mapping/tuning.

I also like the cheap cost of using a donor-tbi unit like I have--or a similar one from a donor car that may deliver better performance/economy than the exact one I have. Really don't wish to spend $2-$3K on one of those all-in-one's! But if they really "deliver the goods"--as may be attested to by some of our forum members who have used them and are happy--I may just bite a $2k-bullet.

A general question: what happens to the original power & low rpm torque in a 1996-1998(?) 5.7 Vortec when going from the 'spider system' to the 4bbl-and-Edelbrock Performer RPM? I am curious if changing to carb usually increases or decreases power and low-end torque? I'm sure driveability and economy will be equal or prolly better; just don't have a clue about torque/power.

Any experience I will appreciate you guys sharing with me.
Thanks,
Sam

[tincan1966]

For what I think is the simplist, I like my OEM TBI system. It retains the look of a carb'd engine, is really pretty maintenance free without alot of parts.
Performance- very smooth throttle response/accelleration. In most setups, will be very efficient because the computer is controlling the fuel mixture.
depending on how your engine is built and the fuel it requires, you may need bigger TBI. The 305 and 350 units are the same but the 454 used one with a few more CFM and bigger injectors.
My Painless harness was very simple to install. I have pics in my build of how I built my first intank pump/return setup, using the stock tank. I have since used my Suburban tank and mounted in the rear, making my own intank pump.

I went this route mainly because I had the car and al the parts I needed, but finding a donor TBI car or truck isn't hard or expensive when compared to aftermarket fuel injection. Nothing wrong with any of those, either, stating strictly from an investment standpoint. I've used the Edelbrock system and the FAST before. Both with very good results.

[luvbowties]

Originally Posted by tincan1966

For what I think is the simplist, I like my OEM TBI system. It retains the look of a carb'd engine, is really pretty maintenance free without alot of parts.
Performance- very smooth throttle response/accelleration. In most setups, will be very efficient because the computer is controlling the fuel mixture.
depending on how your engine is built and the fuel it requires, you may need bigger TBI. The 305 and 350 units are the same but the 454 used one with a few more CFM and bigger injectors.
My Painless harness was very simple to install. I have pics in my build of how I built my first intank pump/return setup, using the stock tank. I have since used my Suburban tank and mounted in the rear, making my own intank pump.

I went this route mainly because I had the car and al the parts I needed, but finding a donor TBI car or truck isn't hard or expensive when compared to aftermarket fuel injection. Nothing wrong with any of those, either, stating strictly from an investment standpoint. I've used the Edelbrock system and the FAST before. Both with very good results.

Thx for reply, tincan. I've looked at the FAST system on Summit for around $1800, w/o fuel pump, but I have several pumps that I can use. But it appears the system does not control engine timing--did the FAST you used control it, or was it just like Summit's? How about the Edelbrock you used, did it control timing? I think this would be an almost 'must-have' to truly get the most from a f-i system, do you?

I also foresee problems when compared to oem tbi: if/when a part fails, you'd hafta stay broke down during ordering parts. Or are the FAST or Edelbrock or MSD systems so bulletproof that this would not be an issue?--I cannot imagine anything that reliable??!!

Does your 454 system have a throttle body that resembles a 2-barrel carb or more like a 4-barrel? And does it still use just 2 injectors?

Thx again for your help and advice.
Sam

[tincan1966]

At the time I installed the Edelbrock, it was a fairly new system, I did this in 2006-07 and I believe it did not control timing, either. The FAST system I did was just like what you looked at-no timing control either. I think the reason for this is on a performance engine, you can tailor your timing to come in slower or faster, seperately,either mechanically or thru the use of controls like MSD, etc. I am going to integrate a MSD distributor and 6AL control box in the future.
I like the fact that mine uses over the counter parts, too, that any parts store carries.
I am using a stock 305, as it was set up. I referred to the 454 because i have seen guys use these for engines with more fuel demand, but the early 454 computers will not control a trans, like a 700R4 because they all had TH400 behind them. Most look like the two barrell version on the 305/350 but I think there are some 4 bbl out there.
With a stock air cleaner from a '94 Suburban, mine looks like a carb'd engine at first glance.

[jayoldschool]

Go to the junkyard, and get the TBI setup off an early 90s TBI truck or RWD full size car (Cadillac Fleetwood/Caprice/Roadmaster). Get the wiring, sensors that you need, and the computer. Grab the in tank pump, too.

[Doktor Hug]

Originally Posted by jayoldschool

Go to the junkyard, and get the TBI setup off an early 90s TBI truck or RWD full size car (Cadillac Fleetwood/Caprice/Roadmaster). Get the wiring, sensors that you need, and the computer. Grab the in tank pump, too.

apparently here in omaha there's some sort of TBI underground...all the junkyards remove them before putting anything out on the lot.

I've seen whole tune port setups (got one myself) show up on craig's for $200, with everything you need to drop it in. Sometimes whole motors for not much more. You could probably go that route and resell some of the stuff you don't use.

[blazins10]

i did a tbi from carb swapo on my 331 sbc and couldnt be happy
im using 454 throttle body (2 in bore) with 350 injectors
and all stock parts from a 1990 truck , the 7747 computer is
what everyone is using and then i had a custom chip burned from old school efi
davis is a genuis !!!
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[66Submarine]

I think your current carb setup is leaving a lot to be desired. 11.5-14.5MPG with 3.73's and OD? My one ton with 4.10 gears and no OD gets about 14MPG. That's with a shot-out 283 and stock jetted two barrel. YMMV, but I'd expect to get about 17-18MPG from your setup with a carb jetted for economy. (My father gets about that in his half ton. Flat top 350 with vortec heads and an out of the box Edelbrock 1406, 3.07 gears and Saginaw 4 speed.)

[66Submarine]

Also, I'll say that me and him both run much more timing than GM tells you to. Retarded timing hurts power, and as a result economy. I haven't done any A-B-A testing to see how much you lose, though.

[luvbowties]

Originally Posted by 66Submarine

I think your current carb setup is leaving a lot to be desired. 11.5-14.5MPG with 3.73's and OD? My one ton with 4.10 gears and no OD gets about 14MPG. That's with a shot-out 283 and stock jetted two barrel. YMMV, but I'd expect to get about 17-18MPG from your setup with a carb jetted for economy. (My father gets about that in his half ton. Flat top 350 with vortec heads and an out of the box Edelbrock 1406, 3.07 gears and Saginaw 4 speed.)

I'd say my reported mileage would probably be much more nearly expected--as well as accurate--than what you reported if driven under same conditions: close to 95% of my driving is in town in 35 mph speed zones and almost never in od--lotsa time spent in 2nd even. Thus, the reason for my original inquiry about f/i--carbs spend too much time in power mode (around this rpm/speed-range)and hoping maybe f/i would yield more 'early' torque along these same speeds, also reaching a cruise mode, and quicker higher gears, at earlier rpm's.
*I have a 3.08 gear, but not going there as I do not want a 'dead dog' in 3rd and od with this automatic.*
BTW: Tell your father to weld his hood shut, lest someone mess with his tuning! That's fantastic mpg IF he's actually getting that under my described driving conditions!
We don't see that mpg in any of the retro's around here--only in SOME of the newer pickups, mostly all hwy. driving, and which use the newer f/i systems.
Sam

[66Submarine]

He's getting that or he'd be on the side of the road, LOL. He used to drive back and forth to Atlanta, seemed even then he got upper teens. He does drive easy, but not insanely so IMO. He has the 3.07 now with no OD, I agree that with OD I think 3.73 is a lot better all-around.

Now, here's the thing I have trouble believing. My totally worn out 250/3 speed/3.73/31x10.5r15 tire half ton. He drove that truck for several months, and I checked the mileage as he did. Driving 50-55MPH on the rural (but hilly) highway to Rome, GA, that damn thing got 18MPG every time. I don't know how, but it did. Also seemed real good in town, pretty close to that.


The one ton does OK, too, IMO. Recently I went on a trip in it to get my '63 dually. Only supposed to be 105 miles round trip. Left out with a mostly full tank, only 105 miles, so no worries, I thought. Thanks in part to my fathers expert map revisions, and the lack of road signs in south GA, it took much longer than expected; about 160 miles. Over half of that was with the dually in tow. It rained real hard, and I had to drive real slow several miles, in third a lot of the time. Ran it hard as it'd go on hills, used the engine to slow it down on the other side, downshifted to every light. Rig weighed over 12,000lbs GCW. Pretty F'ed up. When I got home I still had a few inches of fuel in the tank, or a few gallons. It only holds 18.5 gallons, so you tell me.

I don't know, my luck's always been pretty good.

[Captainfab]

A TBI conversion is fairly simple, and not too spendy, with a lot of aftermarket summort. However, IMO they are a bit outdated anymore. If I was going to go to all the work of converting to EFI, I would go MPFI. That would be either TPI or aftermarket. If you do some research, you can piece together an aftermarket MPFI cheaper than buying the complete kit. There is also the Marine Vortec injection conversion for the Vortec 350's. Those are acutally a MPFI system. Just my .02