How to Put a Vortec Motor in a TBI Truck

[cheapevil]

You'll need the Vortec exhaust manifold, and the convoluted/insulated metal tube and fittings from exhaust manifold to intake manifold, to keep the EGR functional. That manifold may/may not have a threaded boss for the O2 sensor...but maybe your sensor goes in the pipe, not in the manifold. Dorman used to make an exhaust manifold that was "double-tapped" for both the EGR plumbing and the O2 sensor. I wasn't able to find it last time I looked.

The crank position sensor will not be used.

I don't know if the A/C compressor and alternator are in the same places as the TBI. Never paid attention. Wouldn't surprise me if you needed some rework to the wire harness or A/C hose routing to make it fit.

That intake manifold is double-top-secret expensive. Over $500.

So what about going with long tube headers and deleting the EGR and extending the O2 sensor lead to go over to the driver's side? Since that is where the O2 port is located on most of the
LT headers I have found.

 

[Schurkey]

I'm certainly not going to recommend deleting the EGR.

Extending the lead for the O2 sensor probably makes sense, but add the wiring needed for a 3-wire (heated) sensor. You'd need power and ground along with the signal wire; and the power wire should only be hot when the ignition switch is in the "Run" position.

 

[canadaguy5150]

Forgive me if this is a stupid question. Could a guy swap a complete Vortec engine (intake, accessories/brackets, complete harness with black box pcm etc.) relatively easily? I guess my main questions are why swap to TBI intake manifold and will the stock Vortec harness plug into a TBI trucks main plug at driver's side of firewall? Friend of mine wants to swap a complete Vortec setup I have lying around from a wrecked '98 Silverado into his '94 stepside with a seized TBI. Told him would be easier to just put another TBI motor in but he seems to have his heart set on a Vortec.

 

[Schurkey]

Could a guy swap a complete Vortec engine (intake, accessories/brackets, complete harness with black box pcm etc.) relatively easily?

Yes. "Relatively" easy.

will the stock Vortec harness plug into a TBI trucks main plug at driver's side of firewall?

I don't know, but I suspect you'll need some modification there.

Friend of mine wants to swap a complete Vortec setup I have lying around from a wrecked '98 Silverado into his '94 stepside with a seized TBI. Told him would be easier to just put another TBI motor in but he seems to have his heart set on a Vortec.

The engine with the front accessory brackets should drop right in. If this is going into a manual-trans vehicle, make sure there's a pilot bearing/bushing in the end of the crank.

He'll need some exhaust work--installing after-catalyst O2 sensor(s) in addition to whatever would be needed to connect the pipes to the Vortec exhaust manifolds (Might bolt right up.) I don't know about the small-blocks and the number of catalysts--the big blocks have two cats, so two post-cat O2 sensors. Small blocks might be different.

He'll want the Vortec air filter box and tubing including the MAF sensor.

Vortec fuel pump in the gas tank--higher pressure than TBI.

And I have no idea about the computer and wire harness, tuning for the axle ratio, etc. It "can" be made to fit, but I don't know details.

 

[canadaguy5150]

Thank you for your input. Exhaust, fuel pump, accessories, intake assembly etc. are not much of a concern. Mostly concerned about electrical. As I said I have literally every piece of a complete running drive train from a nice truck that was unfortunately side swiped. Just bought the write off for the trans, so the rest is up for grabs. My hunch is this "easy" swap will have a few snags that won't make it as plug and play as he is hoping.
Most likely will end up convincing him to find another TBI or at least swap only short blocks to make life easy. Too many projects on the go, don't need to spend days or weeks scratching my moron head trying to figure out a few wiring issues.

 

[Erik the Awful]

@Tim W asked for pics of my Vortec water pump in a TBI accessory bracket hose routing.

The top hose goes through the hole behind the tensioner.

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The bottom hose makes an immediate U-turn...

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...and goes out on the passenger side lower front. My hose had already been cut back a bit, so I used some conduit to extend it. At some point I'll hit up O'Reilly's and see if I can find a long heater hose with a U in it.

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[canadaguy5150]

Also, I was always of the belief that all TBI motors were roller blocks. I'm reading above this may not be so? Some blocks are roller and some are flat tappet?

 

[Erik the Awful]

As I understand it, the TBIs are all flat tappet, but some of the blocks have roller provisions. The original engine in my '89 did not have roller provisions. Vortecs are all rollers. When it comes to main bearings, the 1500s almost always have 2-bolt mains, and the 2500/3500s almost always have 4-bolt mains. In my humble opinion, the Holy Grail blocks are 4-bolt main TBI blocks with roller provisions. Fortunately my '89 has one, now.

 

[tpass]

I found this info on another forum

"The breakdown goes like this and be aware there are ALWAYS exceptions:

For 350 flat tappet blocks look for casting number 10054727, 14079287, 14088548, and 14101148.
For 350 roller tappet blocks look for casting numbers 10243880, 14011148, 14088526, and 14093638."

Also note the two very similar 148 casting numbers.. easy to get those two confused

 

[PlayingWithTBI]

As I understand it, the TBIs are all flat tappet, but some of the blocks have roller provisions

FWIU Caprices came with roller cams in a TBI engine, and the HD 4 bolt main truck engines put out less HP with lower compression? Don't hold me to it though