350 TBI build

[Marcus W]

I’m planning on building a motor for my truck, something I can drop into when I’m finished it because the truck runs as is, but not well so i want to build a motor that is more lively than stock, but budget in mind what’s the best way to go about it? Stock compression pistons? Mild cam? Heads? Intake? Ported throttle body? Fuel pump/pressure regulator? Chip? Which combination of these parts will show the best results? And I’m doing an exhaust and headers aswell, but I don’t know what headers or system I should go for, I don’t want it to be obnoxious just slightly louder than stock. Thanks.

 

[Erik the Awful]

How much money do you want to spend?

Your biggest hurdles are the stock TBI system and the cylinder heads. It sounds like you're not wanting to go wild, just a nice, little bump in power. The TBI should handle that, and even though the heads are crap, a little bump is reasonable. Big power will require an investment in either tuning tools or a new induction setup.

If you want to swap heads, the Vortecs are a great improvement, but it's not a straight swap - there's stuff you need to know. I did a post a while back, and I'll try to dig up a link for you.

My recommendation:
Do a mild port job on the heads. Do not remove the 'swirl' ramps, and just clean the castings up.

Put in some flat-tops to bump the compression to 9.5:1 - Schurkey has some ideas about quench and sizing it to maximize performance.

If you're hopping up a motor, always replace your valvesprings - a broken valvespring can destroy a motor. I like LS2 beehive valvesprings with Comp Cams 787-16 retainers. They're about 10% stiffer than stock while better controlling higher-rpm harmonics. They also allow big cams, but you don't want to go that route.

If your block has the provisions for a roller cam, but is flat-tappet, do not pass up the chance to upgrade. Sure, the cam is 3x the price, but it's worth it in both performance and break-in confidence. The factory lifters and alignment pieces are dirt cheap - if you don't have a Pull-A-Part handy I'm sure somebody on the board can nab that stuff for you for cheap.

On a 100% stock truck, the best upgrade you can make is the exhaust. What garbage! The pipes are less than 2" and crinkle-bent. If you can weld, you can build a great exhaust system for under $300. If you use the cash-wrench you can buy a nice exhaust for well under a grand.

 

[Erik the Awful]

Here's info on Vortec vs TBI differences.
https://www.gmt400.com/threads/how-to-put-a-vortec-motor-in-a-tbi-truck.49463/

Here's a video on porting TBI heads. I used this as a guide for porting my TBI heads, but I didn't open up the chamber - when I practiced on a garbage head I kept gouging too deep into the head. I did all the rest of the mods he shows. I'd tell you how it runs, but my motor's still in work.

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[PlayingWithTBI]

Stock compression pistons? Mild cam? Heads? Intake? Ported throttle body? Fuel pump/pressure regulator? Chip? Which combination of these parts will show the best results?

All of the above - each component effects the other. If you install headers and free flowing exhaust you need the top end to breathe better.

How much money do you want to spend?

^^^Exactly!

Another option other than Vortec heads are these made by Trick Flow. They flow better than Vortec heads AND have the TBI intake manifold bolt pattern. But again, how much do you want to spend?

https://www.summitracing.com/parts/sum-162109

I cheaped out on a flat tappet cam and lived to regret it. My Mr Goodwrench block has the bosses (drilled and tapped) for the spider and the holes for the cam retainer plate (but not tapped). It would have been an easy swap but the price scared me away.

What year truck are you looking at putting it in? If it's an earlier one that has the 700R4 or a manual trans, you can go with the EBL Flash-II and tune it yourself.

https://www.dynamicefi.com/EBL_Flash.php

Lot's of options, good luck and enjoy!

 

[b454rat]

I put headers n Y-pipe on mine, got rid of cat with 3" pipe, then already had a cat back, but that made a HUGE difference in torque, like swapped a big block in...

 

[Erik the Awful]

I should clarify, I'm a fan of reusing the stock rods and pistons, but my block needed boring, so I went with flat-tops on the new pistons.

 

[RPMerf]

I don't have experience with this, but I found this site. https://harristuning.com/Tbi/recommended-350-tbi-mods/

 

[PlayingWithTBI]

I don't have experience with this, but I found this site. https://harristuning.com/Tbi/recommended-350-tbi-mods/

Some of what he says is good information. It's a start but you should do more research before you decide what you want to do. I bought a chip from him maybe 3 years ago? It didn't give me what I wanted, it's always better to data log, tune, data log, tune, rinse and repeat until you get it right.

 

[Marcus W]

Thank you for all your helpful responses, at this point in still trying to decide if I will build a motor or buy a crate long block

 

[Erik the Awful]

I've said it before, you can build it cheaper yourself, but if you make any mistake, that second set of head gaskets will cost more than if you'd bought a crate motor. That said, I can't stand to see the old motor just sit there, and I'll end up building it anyways.