90' 2500 5.7 to 350 Vortec HO

[haywire69]

I am swapping a very tired (300,000+) TBI 5.7 for a brand new Vortec 350 HO that I picked up for a song. What I need to know is what intake to use, so that I can keep the original TBI, and EGR. Do I need any special brackets etc. And last but not least, do I need to change my computer chip? Any mods you would do while the motor is out to improve the fuel economy?

Thanks my friends.........

[Tim Z]

GMPP sells a vortec TBi manifold, so you can retain your stock TBI. Im cant remember what to do on your egr, but just ask em at GMPP, MY bud put this same motor in his 91 4x4 and kept the TBI but he hade to have a custom chip burned cause of the cam i think.good luck!

[NITROUS]

haywire69, I made that swap before on a 92. I bought the manifold from Scoggin Dickey here in texas and used the stock computer and throttle body from a V6 with no problems. The vortec was a basic 350 with stock lower end. We made a 1" plate to go under the throttle body and added a 100 shot of nitrous. I purchased some 2000 fuel injection manifolds that came with exhaust manifolds, water pumps, and distributers and used the exhaust manifolds to take the place of the older ones. This little truck ran great compared to the stock 350. If you don't have the money right away, use what you have and then work your way to the chip for performance. Like TimZ said if you install a cam a chip will be needed for it to idle correctly.

Good Luck!

[haywire69]

haywire69, I made that swap before on a 92. I bought the manifold from Scoggin Dickey here in texas and used the stock computer and throttle body from a V6 with no problems.

Thanks for the Info guys....now I need to figure out how to get a hold of the people for the intake...
I had a mechanic tell me last night that the TBI would not work on the vortec HO motor, and that I had to install a new computer and the injection system off a late model truck to make it work.....I am taking him to the drug test place this evening....lol..... I know its been 25 years since I made my living as a mechanic, but logic tells me fuel + spark = fire...and I don't see why it won't work....

[Randy_M]

What was done about the distributor and EGR? I am assuming the stock (non Vortec) distributor was used by my concern is the Vortec has a roller camshaft and the stock engine does not. Roller camshafts are a different creature and require a special gear on the distributor, one that will hold up to the very hard material of the roller camshaft. I know this is the case with some TPI conversion when they are put on engines without roller camshafts.

Does the GM Vortec intake have provisions for EGR? It doesn't appear to and I would like to continue to use it so I can pass emissions. Your information and help is appreciated.

[NITROUS]

This will explain everything. TBI to Vortec manifold You'll still be able to pass emissions like I did because you still use the EGR like you asked. I even added a 100 shot of NOS to the stock engine to wake it up. I used the stock TBI distributor with no problems. If you're worried about the gear get you a different one.

[Randy_M]

I have been looking at that manifold and a standard Vortec manifold. With the standard manifold, I would use an adapter plate to mount the TB and an external EGR mount. Pricing the two, it appears the second option would be cheaper and possibly be using a better manifold.

I still have questions about the distributor gear. The original engine have a flat tappet camshaft and the Vortec has the roller. Everything I understand says the roller uses a different distributor gear. Even Scogging-Dickey list this information but no one has mentioned they changed this gear. Before I take a chance and shread a gear (and possibly destroy the engine) I need to confirm this one way or another.

[hummertech]

i did that same conversion, swaped out a 350 tbi for a vortec 350, use the gm tbi to vortec intake, a 96-99 left side truck exhaust manifold, and egr pipe. and resuse all of your tbi stuff, the distributer, egr valve, water neck, tbi all worked good. something is different in the timming requirements for the vortec heads. i cant remember what though... i used a turbo-city chip, they knew what to do. i'm sure somebody here knows how to cook up a cool chip, i also got the injector spacer, tbi spacer, & fuel line spacer. it ran great, passed emmissions perfect, the customer was happy, he only comes in for oil changes now. i think a bigger tbi will add a lot more power. but i didnt want to mess with it.

[haywire69]

Thanks guys......finally finished the construction project I was on, and finally started my swap.
All I have left to do is find the 96-99 exhaust manifolds to support the EGR. I would like to find a set of headers that was EGR ready for the Vortec engine, but have been unsuccessful so far. I will run it with the later model exhaust manifolds until I am successful in finding a set of headers that will work. I should be complete and runninning this weekend, and let you know how she runs.......thanks for all the help! You guys are the greatest!


HAYWIRE

[NITROUS]

I know Edelbrock and JBA make emission legal headers. Here are the JBA's I have on the motor I pulled out. You will be able to use your stock EGR tube with them.