So im finally starting my 350 TBI Vortec swap. Just bought an 85' or so 350 engine from a local yard. Engine already has Edelbrock 4bl carb, intake, headers and camshaft on it, plus a set of aftermarket heads. My plans are to strip the engine down and rebuild it with the following:

Vortec heads casting # 062 off a 99' 350
GM Performance TBI Vortec Intake Manifold w/ EGR
Hooker 2055 Headers 3" collectors
LT-4 HotCam Camshaft
Holley 670CFM TB Unit w/ adjustable FPR
Swap V-Belt accessories for Serpitine Belt

Now i have no idea what kind of internals are already in the engine i have bought until I tear it down, but was told that the previous owner who built the engine was going to use it for his pro built El Camino but eneded up losing his job and selling the whole project to the yard owner who was also a close friend. He parted the car and was going to keep the engine for himself but couldnt pass up the deal i made him for it. But now that u all know my plans i do have some questions:

What year ECM or PCU should i use and from what vehicle?
I was told i can just have my stock computer from my 305 re-flashed and re-tuned to match my setup but is this true?
Will I have to run a different igniton setup for better spark advance?

If anyone has any advise from their experiences on doing a 350 vortec TBI swap please feel free to jump in and lend a hand. This will be my first engine swap so i have alot of questions. Thanks for looking all. I will post pics as i go as well.

 

From all accounts, that is true.
That is part of the computer tune. The computer controls spark advance.

This is really more of a TBI topic than Engine Swap, so let's move it there so the TBI guys can give you the attention you deserve.

 

well so i have run into a snag with my engine. The engine i bought ended up being a early 80's 305 and not a 350 like the yard owner promised. I talked with him and am swapping it for another engine with casting #3970010. Its a 350 block from the years 69-79 with a 4 piece rear main which means it either came from a truck or early Corvette. Also have decided to do away with TBI quite possibly and just go carburated.

 

I swapped to almost the exact same setup. I started with the 305 L03 TBI engine and a 700R4 trans and went to a 355 Tbi with vortec heads and the lt4 hot cam. The swap went great. I did a good deal of prep work before hand. For the fuel system, I started with the holley 670 unit and modified it to fit the standard gm tbi fuel injector pod. The old style holley injectors are terrible. I went through a few too many of them on a 350 tbi pickup before realizing they weren't any good. Holley has since changed the design. I'd verify which style you have if you do go the tbi route. Anyway, I blocked off the stock tbi fuel pressure regulator located on the injector pod and am externally regulating it with a Fuelab unit. You can get fittings that adapt from the injector pod to AN style. I used Earl's brand. I routed the AFPR downstream of the injectors and run about 30+ psi with the standard 61#/hr 350 injectors. I could use to switch to bigger injectors (at least 68's), but the 61's are making due for the moment. I'm also vacuum referencing the pressure regulator to allow for better control of fueling at idle. I'm also using a walbro 190 fuel pump in the tank.

You'll need to have the vortec heads machined to accept the lift of the hot cam. Lift is just under 0.5" with 1.5 rocker arms and 0.525" with 1.6's. I'm running the LT4 valve train (springs, retainers, keepers), which is good to 0.525" lift. I'm using the stock self aligning 1.5 rocker arms.

The block I have is from a 90 C1500 pickup. It's a two bolt main with a 1 piece rear seal and the bosses in the intake valley to allow the spider retainer to be bolted down in order to hold the dogbones tha keep the roller lifters from spinning.

ECU wise, I'm running the stock '746 computer with Craig Moates's (moates.net) Ostrich. It works great for real time tuning. It takes a little bit of soldering on the ecu board, but it is totally worth it. My tune needs more work, but it's driveable. I need to get a wideband 02 sensor on it to really dial it in. Get one if you want to save yourself a bunch of time tuning.

Performance wise, I've been pleased with the engine. I ran it on a dyno with a supervictor intake and a demon 750 before I put the engine in the car. It made 365hp @ 5700 rpm and 363 ft*lb @ 4200 rpm. I don't think it's making that much in the car right now, mostly due to the overly rich tune I have on it at the moment, but I think I'll be right about there once I swap to 1.6 rr's and refine the tune with a wideband.

For more details on the build: https://www.thirdgen.org/forums/tech...c-lt4-hot.html

I know the carb is tempting, but tbi has some great benefits. Even in the dead of Indiana winter, the car starts everytime. I can still get decent highway mileage (~20), and everything can be changed at the tip of my fingers. Let me know if you're looking for some tuning hardware. I have an old pocket programmer and UV eraser that I'd sell for cheap.