95 Chevrolet K1500 5.7 TBI to Carb Swap

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LC2NLS6

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I think so, should be able to use the factory computer to trick it into thinking it has rpm, map sensor and tps sensor. I'm in the same boat buy ditching factory TBI for Holley Sniper.
 

Erik the Awful

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I like both carbs and EFI. I understand both arguments.

It's incredibly easy to bolt a carburetor on an engine and get it running good enough to get you to work and back. Getting a carburetor to run perfect requires carburetor-specific knowledge and a fair bit of artistry.

A stock EFI on a stock motor is incredibly easy to get running right - if every part works. Setting up EFI to work on a non-stock motor requires system-specific knowledge and expensive tools.

You're going to need a bypass fuel pressure regulator. A cheap deadhead FPR won't work, I tried. Here's one for $43. https://www.summitracing.com/parts/mrg-2015
 

Flextx500

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You will definitely need the TPS to make the 4L60E work. I helped my son install a Fi-Tech on a ZZ4 crate motor in his 94 GMC K2500 last year. Hi truck has the 4L80E still controlled by the factory computer. We just made a Y-Harness and tapped it into the existing factory TPS plug. We also connected the tach signal and MAP sensor. It's been working good.
 

badco

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LOL No it won't, it will be an improvement but not quite 2x.
Want to head to the dyno and see it for yourself? I have enough parts to put together a stock tbi engine and i have vortec parts too. The tbi struggles to make 185hp because of head and injection design. The carbed vortec will make close to 390 with flat tappit cam and my old std bore 350 made 428hp with vortec heads, hp car. and a lt1 cam
 

badco

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I didn't used to just shadetree build engines, i worked at a performance engine shop so when the slow season set in i got to do some r&d. The 081 head from a tpi engine, a knock off performer 4bbl intake with a tbi adapter and a 454 throttle body add close to 90hp without tuning.
 

badco

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Beat me by a minute!


Carbs can be tuned to run leaner than stoich at part-throttle/cruise. They have the potential to get BETTER fuel economy than feedback fuel injection that's tuned to run at "14.7:1" if the carb and engine are tuned to run at 15:1 or leaner. But guys are still trying to correct full-throttle fuel ratio on Holley carbs with the MAIN JETS, so it's not likely that you'll find one set up for lean cruise. Carb tuning in general is still apparently a skill that most folks don't have, even for plenty of folks who think they do.

The biggest problems with hard starting are
1. Folks who can't properly adjust the four things on a choke system that need to be correct;
2. Gasoline that may no longer be blended for proper vaporization in cold weather, and
3. Empty float bowls after the carb sits for a period of time--overnight, or a few days. The engine won't start until the float bowls have gasoline; and that takes considerable cranking unless you've got an electric fuel pump that can "prime" the empty carb.

Get the four choke adjustments (choke coil, choke pulloff, unloader, and choke-blade-to-fast idle cam) set properly, get the carb float bowls filled with fresh, winter-blended gasoline BEFORE you start cranking, and a carbed engine will start at -20F. MAYBE it'll even start at -40. In the early days of fuel injection, a properly-set-up carbed engine was MORE likely to start than a fuel injected one when the temperature went to the wrong side of "zero".

The properly-tuned carbed engine will probably need a faster idle, and is less-likely to meet emissions targets especially during warm-up, when the choke is on. That's where FI shines.



Complete agreement.
I could start my holley hp in cold weather and it doesn't have a choke provision at all. The hp is so tuneable with air bleeds all i did was put a fast idle noid on it to up from 900 to 1200 rpm idle. Was on a toggle switch. That engine made 644hp on dyno and even with 456 gears, 5100 converter in a two speed powerglide it would get 8-10mpg doing 4200 rpm at 65mpg on highway
 

Schurkey

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I could start my holley hp in cold weather and it doesn't have a choke provision at all.
I don't doubt this. I've heard similar testimony from other Holley users who don't have chokes, and the engine is claimed to start and run good when "cold".

Many Holley carbs are PIG RICH at idle and low speed, and of course they've got plenty of accelerator pump-shot too.

Of course, these same folks don't define how cold "cold" is. Show up here in January with your no-choke Holley, and see how well it starts in the morning. I have--on rare occasion--seen carbureted cars parked outside, no engine heater (block heater, tank heater, etc.) fire and run at -40. Betcherass they had chokes. By comparison, starting and running at -20 is not such a big deal. In fact, it was pretty routine.
 
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LC2NLS6

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Enginemasters on motortrend on demand, season 2 episode 24. Bone stock cheapy cast bottom end treefiddy. 235 @ 4000 hp 334 @ 3200 tq to 364 hp @ 5600 / 397 @ 4000 tq. The curve gained was huge compared to the stockish swirlport junk when they slapped vortecs on it.
 

Leonidman63

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Make sure you can get a throttle cable bracket that works or you are going to have to build/modify your own. I had bought several that claimed to fit but didn't, I ended up cobbling one up using the original and parts from an aftermarket bracket on my 92 5.7 carb conversion.
 
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