Budget 350 TBI Build

[phantom309]

Hey guys, new to the forum here and hoping to get some help.
My brother and I are going to be rebuilding his TBI, and want to give it some extra pep. I've done TBI's and vortecs before but always a stock build. The plan is to build the engine that is currently in the truck, and does run but is old and tired. It s '94 K1500. Budget is $3-3.5k.
Ive done some research but have had a hard time figuring out answers for some things. Planning to keep the block, crank, pistons. Probably upgrade to vortec heads and a roller cam. Obviously upgrading exhaust headers and pipes. My biggest question is on intake and injection. Whats the best intake to use with vortec head and a tbi? Where do I need to go for tuning the computer? I also don't know anything about choosing the right cam specs.

 

[Schurkey]

Vortec heads are probably a mistake. They're a nightmare to get the EGR working. The intake manifold is over five hundred dollars--or--you use some generic carb'ed intake with an adapter plate.

Get the Summit TBI heads instead. OEM intake bolts right up, all the original accessories drop right on. No headaches aside from needing hardened pushrods and non-self-aligning rocker arms, or use the stock self-aligning rockers and don't install the pushrod guideplates.

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[Russ95]

Save some money n just use the stock heads unless you're really going for that much of a hp upgrade. Im doing a tbi refresh soon, just going down to the bare long block. New cam, springs n seals, rocker arms and intake manifold with 50mm tbi unit. Cam and rockers are roller. Already have full exhaust from manifolds back, 2000 stall converter n 3.73s engine mods will def give a healthy increase while keeping total cost of project around 25/2700. Not opening up the short block due to only having 130k on it

 

[PlayingWithTBI]

New cam, springs n seals, rocker arms and intake manifold with 50mm tbi unit.

Are you going to work the heads at all? It'll be hard getting it to idle well with a 50mm TB, especially with the 7.4L injectors. I have the Summit racing heads with a bored 46mm TB, stock 5.7L 61LB/HR flow matched injectors, running at 20 PSI.

I tried the 17084304 injectors from 91-94 7.4L and my EBL flash-II shut off the injectors completely at idle trying to get close to 14.7 AFR on a WBO2.

 

[Erik the Awful]

What's the purpose of the truck? Tow pig? Mud truck? Rock crawler? Drag race?

Budget $3000 and you might get in under $3500. If you're trying to keep the stock TBI, stick with the stock heads, do a cleanup porting on them, and get a slightly stronger cam. Keep the factory intake. I think your stock bottom end plan is perfect for staying in budget. If your engine has roller cam provisions, clean up a stock set of Vortec roller lifters, pushrods, dogbones, and a spider to put in it. Going roller cam this way only cost me $200 over a flat-tappet hydraulic cam.

Whats the best intake to use with vortec head and a tbi?

That's like asking, "What's the best sauce to use for the asparagus on my hamburger?" Sure, you can do it, but it's just a lousy match. The stock heads are your limiting factor, and if you go Vortec you can go way bigger on the cam, but then your TBI can't keep up, and Schurkey's right - it's a pain getting a TBI to work on Vortec heads. I went Vortec, went big cam, the TBI couldn't keep up, I ended up buying a Sniper and a Summit intake, and now I'm well over your $3000 budget. This is where it's good to know the truck's purpose.

Cam specs? Call your favorite cam manufacturer. Period. Anything else is just internet opinion, and that can make a dog of your motor.

 

[Russ95]

This is a bored small block tbi unit, think it's 50mm but might be 48 id have to get out the paperwork to see for sure. No head work at all, don't want to remove em. Just swapping valve springs and seals. Other than that, new oil pump and pickup, water pump, timing chain, cam, lifters and rockers. Edelbrock 4 barrel intake with adapter plate for tbi and 1" spacer. All told should give a good sized bump in power.

 

[TechNova]

This is a bored small block tbi unit, think it's 50mm but might be 48 id have to get out the paperwork to see for sure. No head work at all, don't want to remove em. Just swapping valve springs and seals. Other than that, new oil pump and pickup, water pump, timing chain, cam, lifters and rockers. Edelbrock 4 barrel intake with adapter plate for tbi and 1" spacer. All told should give a good sized bump in power.

These trucks do have head gasket issues, might be a good idea to replace them when that far in.

 

[Russ95]

These trucks do have head gasket issues, might be a good idea to replace them when that far

These trucks do have head gasket issues, might be a good idea to replace them when that far in.

Third tbi ive had 2nd small block 2 previous had far more miles than this one, never had a head gasket issue. Never overheated one though, my trucks almost always get what they need before they need it. Extremely well maintained. Also figured this upgrade will get me through the next 5 years or so until i have my shop fully set up at which point ill plan a full rebuild w/heads and probably a stroker kit

 

[phantom309]

What's the purpose of the truck? Tow pig? Mud truck? Rock crawler? Drag race?

Budget $3000 and you might get in under $3500. If you're trying to keep the stock TBI, stick with the stock heads, do a cleanup porting on them, and get a slightly stronger cam. Keep the factory intake. I think your stock bottom end plan is perfect for staying in budget. If your engine has roller cam provisions, clean up a stock set of Vortec roller lifters, pushrods, dogbones, and a spider to put in it. Going roller cam this way only cost me $200 over a flat-tappet hydraulic cam.


That's like asking, "What's the best sauce to use for the asparagus on my hamburger?" Sure, you can do it, but it's just a lousy match. The stock heads are your limiting factor, and if you go Vortec you can go way bigger on the cam, but then your TBI can't keep up, and Schurkey's right - it's a pain getting a TBI to work on Vortec heads. I went Vortec, went big cam, the TBI couldn't keep up, I ended up buying a Sniper and a Summit intake, and now I'm well over your $3000 budget. This is where it's good to know the truck's purpose.

Cam specs? Call your favorite cam manufacturer. Period. Anything else is just internet opinion, and that can make a dog of your motor.

The truck is staying pretty much stock aside from the engine and transmission. He just wants to get it going again and also give it a bump in power so it’s more fun and not the pig that these TBIs are from the factory.

How much of a HP increase could be expected with a setup like you are talking about with stock heads?

 

[Erik the Awful]

From everything I've read, the TBI heads are great for economy, but about the worst head for power. I cleaned up the original TBI heads from my truck and followed this video series for porting them. Note that I did not enlarge my combustion chamber as he shows. I haven't put the engine in anything yet to see how it runs.

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There are probably others on this forum who can speak more knowledgeably about how the TBI heads perform on the dyno.

Aside from the heads, your next limitation is the TBI itself. You'll need a tune to get any significant power increase.