EFI Conversion

[Goodle17]

I’m looking at adding an EFI to my 350 as opppsed to the LS Swap. I’m essentially looking for better fuel economy. For the guys who have done this… is it worth the additional cost? I’m seeing units between $900-1500 so I’m curious if it’s worth the money or if I just go ahead and opt for the swap. Any insight for info would be appreciated. I also have duel tanks if that matters? I’m not much of a mechanic lol

 

[Ricko1966]

I'll put a link to a modded tbi truck, You didn't give us much info year,transmission,gearing. TBI could be sourced pretty cheap from the bone yard. But IMHO a properly tuned quadrajet is going to be less trouble less money and almost as good mpg wise. Milage I'd go long tube headers,electric fan,and under drive pulleys. Overdrive transmission and conservative rear gears. Here's the link for the tbi truck

PLUM CRAZY TBI | TBI

 

[DrvnDrvr]

Ive been looking for the same upgrade to my 78 350 4WD K20.

I think Rick is spot on with properly tuned quadrajet is going to be less trouble less money and almost as good mpg wise. Overdrive transmission and conservative rear gears.

There is no quick fix to better fuel mileage on these squares.
10-12 mpg is all your gonna get.

Any mod IF IT WORKS is expensive and a poor return on your investment. MPG wise.

Squares are what they are.

 

[Goodle17]

I'll put a link to a modded tbi truck, You didn't give us much info year,transmission,gearing. TBI could be sourced pretty cheap from the bone yard. But IMHO a properly tuned quadrajet is going to be less trouble less money and almost as good mpg wise. Milage I'd go long tube headers,electric fan,and under drive pulleys. Overdrive transmission and conservative rear gears. Here's the link for the tbi truck

PLUM CRAZY TBI | TBI

Thank you. It’s a 1981, with a 350, K1500. It’s stock and stock can get minus headers. The old boy I bought it off used it as an everyday farm truck and it’s been parked for the last 10 or so years. I’m not even sure what transmission is in it yet. What I do know, is she’s a gutless 350 which is in desperate need of a tune up. After doing some reading, I started looking into the LS Swap, or the EFI route. I’ve definitely considered a new carburetor as well. I didn’t realize there were so many options when it comes to these things.

 

[Ricko1966]

I don't think an ls swap is cost effective for mpg.

Gas Mileage of 1986 Chevrolet Suburban

Search by Model. Search by make for fuel efficient new and used cars and trucks

www.fueleconomy.gov

Gas Mileage of 2002 Chevrolet Suburban

Search by Model. Search by make for fuel efficient new and used cars and trucks

www.fueleconomy.gov

 

[Ricko1966]

Thank you. It’s a 1981, with a 350, K1500. It’s stock and stock can get minus headers. The old boy I bought it off used it as an everyday farm truck and it’s been parked for the last 10 or so years. I’m not even sure what transmission is in it yet. What I do know, is she’s a gutless 350 which is in desperate need of a tune up. After doing some reading, I started looking into the LS Swap, or the EFI route. I’ve definitely considered a new carburetor as well. I didn’t realize there were so many options when it comes to these things.

First get it running and tuned then we'll see what we have to work with.

 

[SquareRoot]

I put sequential port EFI (Edelbrock Pro-flow 4), an NV4500, electric fans and much more on my 85. Cheap? Hardly. But, it starts and runs like a modern vehicle. The OD trans shifts silky smooth and cruises 70 mph at 2300 rpm. On average the mpg is 10 city, 15 highway. Was it worth the money....nope. But it was worth the experience. Would I do it again.. nope. I'd put a factory LS with OD in it and be done with it.

 

[75gmck25]

If you don’t want to use the stock Quadrajet, the Edelbrock AVS 2 carburetor has a good reputation for a daily driver, and is supposed to be a big improvement in low speed driveability over the older 1406.

I’m not knocking Quadrajets (I have one on my truck), but by the time you buy a high quality rebuild kit and do a full rebuild (throttle shaft bushings, etc,) it gets close to the price of a new Edelbrock.

 

[Ricko1966]

If you don’t want to use the stock Quadrajet, the Edelbrock AVS 2 carburetor has a good reputation for a daily driver, and is supposed to be a big improvement in low speed driveability over the older 1406.

I’m not knocking Quadrajets (I have one on my truck), but by the time you buy a high quality rebuild kit and do a full rebuild (throttle shaft bushings, etc,) it gets close to the price of a new Edelbrock.

And when his qjet is right its right its not a one size fits all and works okay. All quadrajets are not the same,they are set up for the application. Lots of variables with a qjet. Kinda like they correct distributor vs. A one size fits all distributor.

 

[memo43]

Agreed with all the responses.
I Installed a summit max efi system to my 85 k20
"was" stock 350/th400 combo with 4:10 gears.
I had the stock Qjet tuned and optimized.
Issue I had is I live at 4300 feet and work at 7200, I was getting about 10-12mpg.
After my 350 was getting tires I swapped an L31 along with the EFi. Now my rig starts every time and is as reliable as my 09 silverado.
I now avg 14-15 mpg my 09 gets 19-20 (has a 4L60 trans)
Do I recommend it, "Yes". Is it as good or better than an LS "Depends". It definitely is a cheaper alternative I'm all in for roughly 1300.
an LS would have been 3500 (all the nickel and dime.)
Ways to improve get an OD trans and gear appropriately.
Don't let the MPG discourage you
look at new trucks an see what they are getting.

Any more question just ask

 

[TPISly-C10]

love my 20mpg $500 6l LS so easy to swap and so much power and reliablitie!

 

[Rumbledawg]

depends on where you live. being out in the flatlands, a well tuned carb would do fine.
i put efi in my truck cause i live in the mountains, doesn't matter if i'm at sea level or 8000ft up, runs the same all day whatever the altitude. plus being a 4x4, i have no off camber starvation issues that i used to get with a carb, plus vapor lock is nonexistent with fi.
doubt you'll see any significant mpg's increase, what you will see with efi is a better all around driver. no pumping the throttle or choking it, just reach in and fires up like a modern truck. efi will also start faster and easier in sub zero weather than any carb. i've made the cost worthwhile in my truck caused i fuel injected my truck 20 yrs ago, so i imagine it's prob paid for itself by now....
only time i would go back to a carb would be for a period correct build, other than that, fi all the way