How to Put a Vortec Motor in a TBI Truck

[alpinecrick]

Another difference is the roller cam plate on the front. My TBI motor had these provisions and used a different sized plate than the one I had from my Vortec block. There was only 2 sizes if I recall so it's easy to tell which one you need.

The TBI 195-210 hp/300 ft lbs, the Vortec 250-255 hp/330 ft lbs.

The Vortec had the cast iron version of the 'vette aluminum heads and are probably the best flowing heads Chevy ever put on a SB.

 

[Erik the Awful]

Doh! I remember there being a problem with using the retainer plate from my Vortec on my roller TBI block.

Now I'm wondering if there's a difference between the thickness of the upper timing gear, or if the thickness of the cam retainer is machined off the front of the block? I don't have a roller block handy to compare.

Sorry, alpinecrick, but they're a whole different head.
"Starting in 1996 on several GM Trucks and Vans, the L31 Vortec heads came on the scene. Not just a modification of existing heads, but complete redesign using the 1996 Caprice/Impala SS LT1 cast-iron head castings as a base. The biggest change GM made in the new design was revising the water jacket so the new Vortec heads could be used on conventionally cooled small blocks. The idea of using the 1996 LT1 cast iron head as a starting point for a new performance stock head came from the fact that it was the highest flowing LT head used by GM. The 1996 Caprice/Impala heads outflowed the Corvette Aluminum LT1 heads by as much as 20 cfm on the intake side. The cast iron Vortec head was in development six months longer than the aluminum head, and during that time, GM engineers tweaked the intake and exhaust ports for additional flow."
https://www.onedirt.com/tech/engine/a-guide-to-vortec-vs-oe-small-block-chevy-heads/

 

[Casey Price]

So Question if I wanted to put Vortec heads on my tbi block I would just need the heads, 4 Barrel carb intake and adapter plate? Also I'm sure there would be some fabricating of lines involved..
I already have a Modified Throttle body with 18LB spring and a chip with EGR delete.

 

[Erik the Awful]

If you put Vortec heads on a TBI block, you would also either need to drill the bypass passages in the Vortec heads or run the Vortec water pump. If I were to do it again, I'd drill the heads. Routing the Vortec bypass on a TBI truck looks funky and not-stock.
View media item 32348View media item 32318

 

[Casey Price]

If you put Vortec heads on a TBI block, you would also either need to drill the bypass passages in the Vortec heads or run the Vortec water pump. If I were to do it again, I'd drill the heads. Routing the Vortec bypass on a TBI truck looks funky and not-stock.
View media item 32318

So where do the bypass lines run to is that for the heater?

 

[Schurkey]

So where do the bypass lines run to is that for the heater?

Post #14. There are no "lines" in the pre-Vortec bypass on small-blocks.

 

[Casey Price]

Post #14. There are no "lines" in the pre-Vortec bypass on small-blocks.

I should of worded that differently. What is the purpose of the bypass lines?

 

[Schurkey]

There are no "lines" in the pre-Vortec bypass (small-block).

The bypass allows some coolant circulation when the thermostat is closed.

 

[Erik the Awful]

You get funky temperature spikes without a working bypass. I didn't know about it when I built my engine, but it originally went in my '99 Suburban, so it didn't matter. When I swapped it into my '89 Stepside I had to switch to the Vortec water pump. If the heads ever come off I'll drill the passages.

 

[Shawnstockham]

"Can I swap a Vortec motor in place of my TBI motor and does it just bolt in place?"

Yes, you can swap a Vortec motor in place of a TBI motor, but no, it doesn't bolt in place. So, what does it take?

Head and Intake Differences:
The Vortec manifold has eight bolts, two on each corner, drilled vertically, higher on the head, versus the TBI intake that has two in each corner, drilled perpendicular to the mounting surface, and an additional two in the middle of each side. You would need to drill and tap holes to physically mount a TBI manifold to Vortec heads, and that doesn't fix the problem of covering the intake ports. You might get away with using the Vortec mounting holes to "clamp" the outer edge of the TBI intake, but I'm not stupid or desperate enough to do it. The Vortec intake bolts are significantly smaller, and you'll be putting them in shear as well as tension.

View media item 32351Pic: Note the differences in bolt holes.

The Vortec intake manifold has taller ports, and the TBI manifold doesn't cover the openings. Some people have proposed welding to build up the top outer edge of the TBI port and then porting the inside to match the Vortec port, but that's a lot of welding on an aluminum intake. Good luck with that. If you're sane, you'll want a Vortec-specific intake.

View media item 32352Pic: Intake sitting with TBI head on the left, Vortec head on the right. Note the gap at the top of the intake port and the bolt holes above the manifold mounting surface

The Vortec heads are missing the coolant bypass hole that the TBI and earlier heads have. Without a coolant bypass circuit you will get weird overheating events.

View media item 32348Pic: Note the bypass hole in the TBI head at left, missing on the Vortec head at right.

The exhaust gas crossover port through the intake manifold is blocked off on Vortec heads.

The valve covers on Vortec heads have a narrower PCV baffle. It's almost unnoticeable, but if you switch to aluminum roller rockers, the Vortec valve cover will sometimes fit when TBIs won't.

The missing center holes preclude the ability to mount the engine controls on the passenger side of the intake. I relocated mine to the valve cover. I mounted my coil off the back, driver's side of the intake. It has long enough leads to put it anywhere out of the way.

The TBI intake gaskets often have a piece for blocking off the rear coolant passage through the intake. Some intakes have a rear coolant passage, some don't. I don't use the coolant block off in the gasket. If my intake has a coolant passage, the coolant will flow. If it doesn't, the coolant won't flow. Simple as that.

Block Differences:
The big difference in blocks has already been mentioned - the coolant bypass. TBI water pumps have an internal coolant bypass built into the pump, block, and heads. The Vortecs changed to an external coolant bypass that runs from an extra port on the water pump to the intake manifold. If you put Vortec heads and a Vortec block in a TBI and want to keep the internal coolant bypass, you will need to drill a hole in the front of the passenger head, drill a hole in the block and run the TBI water pump. I suggest also drilling the rear of the driver's head to prevent future problems if you swap them around.

If you use the Vortec water pump on a TBI block you must plug the coolant bypass port on the block. The port in the block is between sizes for a standard bolt thread, so I tapped mine metric (M10x1.5) and found a bolt that would thread in it. I cut the head off the bolt, put a slot in it for a flathead screwdriver, put some RTV on it, and threaded it in until it was flush.

View media item 32347Pic: Note the untapped coolant bypass hole below the water pump bolt hole.

The fuel pump lever hole is likely undrilled on all the Vortecs, and is usually undrilled on TBI blocks. It's immaterial for most of us.

All Vortecs have roller provisions. TBIs likely don't, but there are exceptions. Having the provisions means upgrading to a roller cam pretty cheaply. Without the provisions you have to buy higher-dollar retrofit roller lifters if you want a roller cam.

The Vortecs have plastic "Do Not Re-Use" timing covers that are missing two bolts from the traditional timing covers. Most people don't have any problems with leaks from leaving those bolts out when swapping between timing covers. You can re-use the Vortec timing covers. Just be sure and put a dab of silicone in the corners.

The Vortec timing cover has a hole for the crank sensor. You'll want to plug that hole or use a TBI cover on a TBI motor.

View media item 32349Pic: Note the missing bolt holes and the crank sensor hole.

The balancer is shorter on a Vortec than a TBI, to fit the reluctor wheel for the crank sensor between the lower timing gear and the balancer. Note that if you keep the reluctor wheel you cannot use the TBI timing cover. You can't use the Vortec balancer without the reluctor wheel.

View media item 32350Pic: Note the reluctor wheel, stacked with the balancer in the timing cover. The reluctor wheel does not fit inside the lower lip on the TBI cover.

As stated earlier, the Vortec water pump has extra coolant ports for the coolant bypass. The extra port should be routed directly to a threaded nipple on the intake manifold's front coolant crossover. There's a nice hole in the accessory bracket to make this easy.

View media item 32317Pic: Note the coolant pipe on the right side of the Vortec water pump. This needs to go to the intake manifold's coolant port. The left side coolant pipe goes to the heater. On a TBI motor the intake manifold coolant port goes directly to the heater.

Once you swap to an aftermarket intake manifold, the serpentine belt support brackets don't fit. You'll be engineering your own solutions. If you have a welder, chopping the brackets and re-welding them to fit is your best option.

Intake swaps
GM Performance Parts' TBI manifold for Vortec heads is $540! Expensive, but this is a bolt on solution for guys who need EGR and don't want to fabricate.

Summit's cheapest aftermarket Vortec manifold for a carbed application is $160 and a TBI adapter is $35 and up. The $35 adapter is simply a 1/4" steel place with bolt holes. The TBI bores are wider than a square bore, so part of your TBI bore will be shrouded by the edges of the intake manifold. If you use a spread bore intake the shrouding is minimal. The true TBI to carb adapters run about $160 and add an inch of space.

View media item 32353Pic: Note how the sides of the square bore on the left jut into the TBI's airflow. The spread bore on the right does not. I didn't have a square bore manifold handy, so both pics are the TBI adapter laid over my square-to-spread bore adapter.

Most aftermarket intakes do not have EGR provisions. There may be an external way to do it, but I have no experience with it.

The brake booster port on a TBI manifold is at the front driver's side of the throttle body. My aftermarket intake had it on the right rear. I put the brake booster tube in my vise, bent and unbent it, and rerouted the hose. You might have to be creative.

The throttle and TV cable are critical! If you get the GMPP manifold, it's likely a bolt-on affair. With any aftermarket intake you're probably going to have to tweak the mounting to keep your TV cable aligned and properly tensioned. There is plenty of advice out there for adjusting your TV cable, but remember that if you get it wrong, you can quickly trash your transmission. You also want to ensure your throttle plates close and open fully, without undue tension when you floor it.

My engine is a TBI block with vortec heads. As I can decifer, the TBI water pump will work as the bypass port will flow. What is the port just driver side of the thermostat housing?