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73-87 Chevy _ GMC Trucks => Performance => Topic started by: 77c10diesel on November 23, 2010, 08:48:12 pm

Title: Carb vs FI, is it worth the money to swap?
Post by: 77c10diesel on November 23, 2010, 08:48:12 pm
I am looking at buying another 73-87 truck to use as a daily driver to replace my Cummins Dodge. I was thinking about the FI conversions out there and it got me thinking about some of the gas mileage posts. My truck will be mostly stock, 3/4 ton, but I do not know if I will go big or small block yet, guess it depends on what I find.
I was wanting to know if a conversion over to FI would be worth the money? I know someone here must have done it and can report on the fuel savings. However if the savings is only 1-2 MPG and the conversion is over $1000 it seems that the payoff would be a long time off. As apposed to a good intake and a well tuned carb and engine.
What do you think?
BTW I know a 3/4 ton with a gas engine will never reach the mileage that my Cummins gets, however when I drop the $380 a month payment and drop my insurance down, I can buy a lot of gas. Its only at 17 MPG anyway.
Title: Re: Carb vs FI, is it worth the money to swap?
Post by: Layne on November 23, 2010, 11:51:53 pm
Holley and edelbrock have a drop and go kit that might work with sbc vs bbc, but if you decide on either, Tbi is fairly simple.
Title: Re: Carb vs FI, is it worth the money to swap?
Post by: VileZambonie on November 24, 2010, 12:13:23 am
If you're going TBI just use a factory system from a donor. AS far as fuel economy goes, don't keep your hopes too high. These aren't economical trucks.
Title: Re: Carb vs FI, is it worth the money to swap?
Post by: Captkaos on November 24, 2010, 09:26:56 am
My 91 1T with a 350TBI and a 4L80E gets 14city/17highway.
You aren't going to exceed that by much with a standard SBC in a 3/4T truck with low gearing

My 87 1/2T with 305TBI and 700R4 gets 15city/22highway driving 65mph.

I would put a factory TBI on it if you get a donor.  I wouldn't waste my money on aftermarket TBI or EFI systems if you aren't after pure performance.
Title: Re: Carb vs FI, is it worth the money to swap?
Post by: fitz on November 24, 2010, 02:06:29 pm
As far as donor vehicles go do you guys recommend reusing the factory TBI wiring harness or would you go with an aftermarket kit like the one from Painless ($400).
Title: Re: Carb vs FI, is it worth the money to swap?
Post by: 84c20 on November 24, 2010, 03:40:12 pm
why not try find a diesel, the 6.2 is slow but very cheap to run from what i hear.
Title: Re: Carb vs FI, is it worth the money to swap?
Post by: 77c10diesel on November 24, 2010, 05:27:21 pm
Thats good to know. I had a 1989 Suburban 2wd, 454, THM400 and I think the best I ever got was 12 MPG and it was TBI.
I guess if I find a great deal on a donor truck, or happen on the right truck I will go with it, otherwise I will stick with the carb.
Title: Re: Carb vs FI, is it worth the money to swap?
Post by: polish pete on November 24, 2010, 07:25:13 pm
I am looking at buying another 73-87 truck to use as a daily driver to replace my Cummins Dodge. I was thinking about the FI conversions out there and it got me thinking about some of the gas mileage posts. My truck will be mostly stock, 3/4 ton, but I do not know if I will go big or small block yet, guess it depends on what I find.
I was wanting to know if a conversion over to FI would be worth the money? I know someone here must have done it and can report on the fuel savings. However if the savings is only 1-2 MPG and the conversion is over $1000 it seems that the payoff would be a long time off. As apposed to a good intake and a well tuned carb and engine.
What do you think?
BTW I know a 3/4 ton with a gas engine will never reach the mileage that my Cummins gets, however when I drop the $380 a month payment and drop my insurance down, I can buy a lot of gas. Its only at 17 MPG anyway.

why not just get an older 12v cummins instead, it will get great mileage and be fairly priced, just an option.
Title: Re: Carb vs FI, is it worth the money to swap?
Post by: VileZambonie on November 24, 2010, 07:28:28 pm
As far as donor vehicles go do you guys recommend reusing the factory TBI wiring harness or would you go with an aftermarket kit like the one from Painless ($400).

Use the factory harness ($FREE)
Title: Re: Carb vs FI, is it worth the money to swap?
Post by: Captkaos on November 24, 2010, 11:01:18 pm
ditto on what Vile stated.
Title: Re: Carb vs FI, is it worth the money to swap?
Post by: grinder1989 on November 25, 2010, 09:53:43 am
I agree with the others.  Factory TBI units are cheap and plentiful.  You can find a harness, injector and computer at any junk yard.  I prefer carburetors but that's just me.  Go to the junk yard and save yourself a lot of money.