Tbi 350 to Vortec 350

[PlayingWithTBI]

Selecting parts and tuning to make the engine run rough instead of selecting parts and tuning for power will get you LESS power.

^^^X2 - I will try to quote a very knowledgeable person who has designed and built ECMs for years "When it sounds and acts smooth, you're developing HP" or something like that,LOL.

I've had big block engines with 320* duration and .625" lift (Isky 320 in a GTX 440 tri-power) that wouldn't idle under 1200RPM when I was a kid, couldn't drive it in traffic but, DAMN, it sounded cool! I also realized after 3 builds, it won't turn 7000RPM without scattering, expensive lessons...

 

[Trigger_guard]

Agreed. Choppy idles sounds good. But usually come with a gang of other problems. Low vacuum, no low rpm torque, finiky cold starts, ect...

You can achieve a similar effect with a mild cam and very low rpm idle. But that will depend on how strong your oil pump is, and if your efi will let you

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[Blanco_obs]

I’m considering just building a 350hp sbc. When people see my truck they don’t expect it to run. I’m kinda considering the fact that everyone says no chop lol. Although it sounds bad ass hahaha


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[b454rat]

My TBI 406 had an awesome idle, had good brakes, and had gobs of torque off idle till I let off. Even if you put a roller cam from a vortec motor with some headers it will make a difference. Building an engine can spiral out of control so fast. Best is to KISS. Keep It Simple Stupid lol

 

[Erik the Awful]

Blanco, I went a similar route as you, only my truck has a 700R4, and if I'd been a little more far-sighted I probably would have ditched the TBI without spending any money on it and went with a carb for a temporary fuel system.

I decided that if I was rebuilding the motor, I wanted to cam it, so I did. In doing so I discovered the TBI is pretty limiting and costs nearly as much as a bolt-on EFI.

When it comes to manifolds, the Holley TBI Vortec manifold is $400, and limits you to the TBI. The Vortec squarebore manifolds are adaptable to most anything and can be had for well under $200 - which is why I went that route. Also, my end goal was a bolt-on EFI system.

I finally figured out the TBI was a dead end for me and my best option at that point was to make the jump to a Holley Sniper, and I'm glad I ripped that bandaid off. It took about four hours to install and I finally drove my truck.

 

[Blanco_obs]

Blanco, I went a similar route as you, only my truck has a 700R4, and if I'd been a little more far-sighted I probably would have ditched the TBI without spending any money on it and went with a carb for a temporary fuel system.

I decided that if I was rebuilding the motor, I wanted to cam it, so I did. In doing so I discovered the TBI is pretty limiting and costs nearly as much as a bolt-on EFI.

When it comes to manifolds, the Holley TBI Vortec manifold is $400, and limits you to the TBI. The Vortec squarebore manifolds are adaptable to most anything and can be had for well under $200 - which is why I went that route. Also, my end goal was a bolt-on EFI system.

I finally figured out the TBI was a dead end for me and my best option at that point was to make the jump to a Holley Sniper, and I'm glad I ripped that bandaid off. It took about four hours to install and I finally drove my truck.

I was looking at the fitech which I guess is a little more afforded then the other ones but this is what I’m looking for info like this.


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[Blanco_obs]

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[Gramps]

The tbi motor I built left the dyno making 300hp/385ft-lbs. using the stock GM intake manifold, slightly modified tbi unit, and stock ECM.

There’s still some power that was left on the table I’m sure with some tuning could squeeze every bit out of it but that wasn’t the goal, a good bump in power and driveability was what we were after.

TBI’s have their limits but those limits are well beyond what the engines came with. Just have to combine the right combination of parts.


But if you just want to “sound cool” put a huge cam in, plop on a carburetor, and idle around rumpety rump. Don’t forget to hack off the exhaust somewhere before the cat and straight pipe it.

 

[Kris901]

I’ve gotta 94, I just recently swapped in a vortec .030 over with a decent cam, I’m running the dual plane pro comp intake with a Holley 4160. Got my first fire last night. Shoot me a message if you have any questions. I also retained the TBI pcm to keep running my fresh built 4l60e

 

[L31MaxExpress]

I’ve gotta 94, I just recently swapped in a vortec .030 over with a decent cam, I’m running the dual plane pro comp intake with a Holley 4160. Got my first fire last night. Shoot me a message if you have any questions. I also retained the TBI pcm to keep running my fresh built 4l60e

Same engine would run better with a big block TBI and some PCM tuning.