5.7L Vortec build for the '94.

[94Sierra4x4]

Well the time has come to start gathering parts, things have been falling together quite nicely and I think it's time to pull the 350, throw her on a stand, and start the tear down.
Even better I was just given a free parts washer from work, too much paperwork for them to keep it there, lmao!

This will be my first engine pull/rebuild/swap..

I'll probably tear it down to the block and rebuild the whole top end, i'll check out the bottom end but if it's in good shape, she'll stay that way.
Definitely a few things I am unsure about, I want to throw in a little meaner cam, not sure what would be a good one really. I know I won't need much because this gutless 305 will make ANYTHING look like a hot rod. But anyways, it'll be a daily driver for the most part, eventually turned into a 4x4 weekend toy, so I'd like the low end torque for that aspect, but I do drive a bit of highway to work, (max, 50-60mph)

5.7L Vortec build..

So, any cam suggestons?
Will I need to replace lifters, push rods, rocker arms etc? (I'd like to anyway?)
Replace valves? I guess if they look worn?
Vortec to TBI intake manifold... (yeah, I'm staying TBI, for the time being)

Obviously pick up some good gaskets..
Long tube headers are on the list as well.. might as well right.

At the end, I'll do some datalogging and hopefully get tbichips or someone to fix me up with a tune to make it all wake up
As far as I know I can just unplug everything from my TBI, and plug it in the Vortec and she'll be good to go.. anyone know any better?

 

[dkennedy]

I just rebuilt the upper end of my 5.7, and one thing I would strongly suggest is that you take the heads to a machine shop and have them vatted and magnafluxed. They are bad about cracking at the middle head bolt area and in the exhaust seats.

 

[94Sierra4x4]

I just rebuilt the upper end of my 5.7, and one thing I would strongly suggest is that you take the heads to a machine shop and have them vatted and magnafluxed. They are bad about cracking at the middle head bolt area and in the exhaust seats.

Awesome I'll keep that in mind!

Looking for ~250hp/~300 ft lbs torque as a rough estimate, if anyones curious

 

[95Escahoe]

Mod the TBI unit

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[94Sierra4x4]

Mod the TBI unit

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Ultimate TBI mods?

Was thinking of going to 454 throttle body, bigger injectors. Necessary?

 

[95Escahoe]

Ya the ultimate mods and depending on what you do the 454 setup would help

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[94Sierra4x4]

Soo.. take the '97 Vortec motor, add the TBI+the manifold req'd...

I'm pulling out a 305..
Do I need a diff ECM?
Any different sensors?
Will everything be plug and play once the tbi system is bolted on to the sucker?

 

[woody80z28]

I did this a couple years ago and there are some things you need to know.

Stock calibration will not work. It will run, but will run worse than stock... You will need to tune the ECM. Since you are 5spd stock, I believe you got the slower ECM. Mine was originally auto and had the '7427 which is a great computer for tuning. You may want to look into converting your truck to the 7427. They are easy to find in any 94 4L60E truck and cheap. www.gearhead-efi.com has a lot of info on the swap.

Used Vortec heads are almost always junk. I got two pairs of used ones and every single one was cracked between the exhaust valves on 3-5 and 4-6. You can get brand new GM ones on ebay for about $550.

The Vortec 350 will already have a roller cam that is a little bit hotter than the TBI. An LT1 Camaro cam is a good upgrade. It gives you a little bit more duration with quite a bit more lift. Lift is still just low enough to be ok with stock Vortec valve springs. I would clean all the used roller lifters really good or just buy new ones. I reused some stockers and ended up replacing them a couple weeks later because one was ticking. LS7 Corvette lifters will work and they're a little over $100. Cheap insurance. Rocker arms & pushrods should be fine.

Keep your throttle body and get 350 injectors. Then just bump your fuel pressure with a TPI pump and drill & tap the regulator to be adjustable. I set mine to 20psi to feed 300hp.

Vortec intake gaskets suck, so get the metal FelPro "PermaDry" ones. MS90008T if I remember correctly.

Any other questions, let me know. My build thread has a lot of this stuff in it, take a look.

 

[94Sierra4x4]

I did this a couple years ago and there are some things you need to know.

Stock calibration will not work. It will run, but will run worse than stock... You will need to tune the ECM. Since you are 5spd stock, I believe you got the slower ECM. Mine was originally auto and had the '7427 which is a great computer for tuning. You may want to look into converting your truck to the 7427. They are easy to find in any 94 4L60E truck and cheap. www.gearhead-efi.com has a lot of info on the swap.

Used Vortec heads are almost always junk. I got two pairs of used ones and every single one was cracked between the exhaust valves on 3-5 and 4-6. You can get brand new GM ones on ebay for about $550.

The Vortec 350 will already have a roller cam that is a little bit hotter than the TBI. An LT1 Camaro cam is a good upgrade. It gives you a little bit more duration with quite a bit more lift. Lift is still just low enough to be ok with stock Vortec valve springs. I would clean all the used roller lifters really good or just buy new ones. I reused some stockers and ended up replacing them a couple weeks later because one was ticking. LS7 Corvette lifters will work and they're a little over $100. Cheap insurance. Rocker arms & pushrods should be fine.

Keep your throttle body and get 350 injectors. Then just bump your fuel pressure with a TPI pump and drill & tap the regulator to be adjustable. I set mine to 20psi to feed 300hp.

Vortec intake gaskets suck, so get the metal FelPro "PermaDry" ones. MS90008T if I remember correctly.

Any other questions, let me know. My build thread has a lot of this stuff in it, take a look.

Fvckin' rights man thank you for the info! I'll be all over that build thread like a dirty shirt!

So yeah I believe my ECM is a bit of a slouch, was brutal getting set up for datalogging because I couldn't find vehicle def files for my ecm.
Simply swap out the ECM with a 94, 350/4l60e truck, does it matter that I'm a 305/5spd and not a 350/5spd?
Of course need to tune out the auto tranny afterwards, but may aswell get a custom tune done at same time to wake her up a little more?
Is it going to be a cut/splice/solder show for the ECM switch? I'm really not sure..

So if I wanted to do a bigger cam, i'd have to go with different roller lifters, valve springs,rocker arms & pushrods, right?
I'll most likely go with the LT1 Camaro cam and LS7 Lifters as you suggested for the simplicity.
This will be my first engine pull, let alone my first engine overhaul

TPI pump as in, Vortec fuel pump? Regulate it down to 20psi via the adjustable fpr.. werd!

I will have the heads checked out by a machine shop and if necessary they will be replaced with new ones.

Do 305/350 injectors flow at different rates?
Sounds good on the intake gaskets, FelPro PermaDry it is.

 

[woody80z28]

Here's a link about the ECM swap. Take a look to be sure your ECM is one of the 8746/6965/7747/299. You will definitely need a custom tune. Without question. The auto-to-5spd part is the easiest of the whole tune though...just one checkbox for "manual trans". The fueling and spark tables are where it will need the most work. I used the spark table from an LT1 6spd Camaro because the LT1 heads are similar to the Vortecs and the manual loads the engine differently. I originally had an auto LT1 spark table that sucked.
http://www.gearhead-efi.com/Fuel-In...with-Wiring-Pinout-Directions!&highlight=7427

For a bigger cam, you'd need better valve springs, but the LS7 lifters and stock rocker arms should be fine. Remember you will need to use the Vortec rocker arms because they are self-aligning, and the Vortec pushrods because they are the correct height for the roller lifters. An LT4 hotcam would be an option that still should be pretty torquey and EFI-friendly.

TPI pump as in 90 Camaro TPI. And there is a how-to online for converting your stock regulator to be adjustable. I think I even have pics in my thread. Yes, 350 injectors flow more, and you will need it for the build. 350 injectors and 20psi will feed about 300hp.