How to Put a Vortec Motor in a TBI Truck

[Schurkey]

IF the heads and the block is drilled for the coolant bypass...

...don't you have to run a TBI water pump, because the Vortec pump doesn't cover the bypass opening in the block?

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You'd either have to thread the opening in the block and cram a plug into it--flush--so there's no way it can interfere with the water pump mounting; or you'd have to leave the head un-drilled so there's no water in the block bypass passage to begin with.

This is the block that's in my truck now, with a TBI water pump and non-Vortec heads. I drilled the bypass hole and also the two bolt holes for the timing cover. (No photo of the timing cover holes after drilling and tapping, though.) You can see where the Vortec water pump doesn't cover the bypass opening.

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[Erik the Awful]

Good point. The heads on the motor in WCJr aren't drilled, and I'm running the Vortec water pump, but I went ahead and installed a plug in the bypass hole on the front of the block. Basically, I tapped threads, hacksawed a slot in some all-thread, RTV'd it, and screwed it into the block.

 

[rebelyell]

I won't bet on it, but suggest the tall-deck BBC truck 427T motor may require more torque; because 427T piston has 4 rings, not 3.

 

[rebelyell]

I have Vortec heads on an 880 TBI block in WCJr. I did not know about the bypass when I built the engine; it was my first SBC build, so it's not drilled. That's why I switched back to the Vortec water pump.


That sounds like the big block Caddy thermostat. If you run a normal thermostat in its place you get overheating.

Checking RockAuto... Yup. Same style, but apparently different size.

Vortec - https://www.rockauto.com/en/moreinfo.php?pk=3952968&cc=1353327&pt=2200&jsn=1056
Caddy - https://www.rockauto.com/en/moreinfo.php?pk=4483863&cc=1409374&pt=2200&jsn=1227

I learn something new every day!

Yup, both t'stats share same design/style. I don't recall working on a late Caddy. But when I look at the Vortec t'stat application list, I see it's also identical t'stat used in late (Panther chassis) Towncars and Crown Vics. I also have a couple final gen TCs w/ that 4.6L SOHC V8. I now recall how I had once thought the two t'stats (each w/ lower disk valve) looked a lot alike; well, I see now that's because they Are same. I never had cause to pull them in order to compare side-by-side; but they're clearly same.
I too learn something new!

 

[Majoraslayer]

After taking a break for a few weeks from my project, I'm back again.

If anyone has done this conversion with a GM Performance Parts intake (or possibly any other conversion intake), how did you set up your accessories' rear support rods? They stabilize the accessories to reinforce the bracketry (and I've heard that tends to crack if you delete them). On the factory TBI setup they connect to studs used as mounting bolts for the original TBI intake. Since the new Vortec heads and intake don't have the same angled bolts, I'm curious how everyone else handled those support rods on their build.

 

[GoToGuy]

Those support rods come in about at least six different combinations. Longer, shorter, less angle on the attachment ends. The last time at the treasure yard a few were just laying in eng bays, so I brought home seven that needed a home.
I'd try mix and match, see what works.

 

[Erik the Awful]

I modified the alternator brace. Note that the stud spacing the bracket out is only there because the header flange is significantly thinner than the original manifold. I have not modified and refit the A/C compressor brace, but as soon as I get the A/C running I'll add it.

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[Majoraslayer]

I forgot to mention it, but I decided to swap to the two-piece aluminum accessory brackets since the big steel bracket supposedly has a reputation for cracking. Several years ago I had picked up a set from a junk yard and never installed them, so having it all apart for this build seemed like the best time to do a conversion. The main problem I've had is that I've never used this setup before, so I wasn't sure where the brackets even go on the original factory setup. Thanks to a guy on Facebook who snapped a couple pics for me though, I think I have a a decent idea of what to do.

From the pics I got, it looks like the two-piece aluminum setup may simplify the rear braces a bit vs. the '88 steel bracket according to pics I've seen. I only saw three braces: two that mount behind the idler pulley, and a one-piece bracket that bolts to the manifold, rear of the power steering pump and rear of the alternator. I managed to find the big rear bracket piece, and since I have headers too, had to trim part of it off and improvise a long exhaust mounting stud with a couple of old lug nuts as spacers.

That only leaves figuring out the idler braces. I'm hoping I can get away with running just one; it looks like one brace goes to one of the angled TBI intake bolts, while the other seems it may go to a bolt hole in the center that the GM PP intake may actually accommodate. The main question is whether I actually have that brace in my big pile of spares. It's possible the reference truck from my pics was missing some kind of brace for the A/C compressor, but it didn't show one. I do know my original setup had one, but for now I'm deleting my entire A/C system anyway and running a bypass pulley until I can afford all new components.

 

[aledfelt]

I forgot to mention it, but I decided to swap to the two-piece aluminum accessory brackets since the big steel bracket supposedly has a reputation for cracking. Several years ago I had picked up a set from a junk yard and never installed them, so having it all apart for this build seemed like the best time to do a conversion. The main problem I've had is that I've never used this setup before, so I wasn't sure where the brackets even go on the original factory setup. Thanks to a guy on Facebook who snapped a couple pics for me though, I think I have a a decent idea of what to do.

From the pics I got, it looks like the two-piece aluminum setup may simplify the rear braces a bit vs. the '88 steel bracket according to pics I've seen. I only saw three braces: two that mount behind the idler pulley, and a one-piece bracket that bolts to the manifold, rear of the power steering pump and rear of the alternator. I managed to find the big rear bracket piece, and since I have headers too, had to trim part of it off and improvise a long exhaust mounting stud with a couple of old lug nuts as spacers.

That only leaves figuring out the idler braces. I'm hoping I can get away with running just one; it looks like one brace goes to one of the angled TBI intake bolts, while the other seems it may go to a bolt hole in the center that the GM PP intake may actually accommodate. The main question is whether I actually have that brace in my big pile of spares. It's possible the reference truck from my pics was missing some kind of brace for the A/C compressor, but it didn't show one. I do know my original setup had one, but for now I'm deleting my entire A/C system anyway and running a bypass pulley until I can afford all new components.

Looks like I am a few weeks behind you doing the same thing: vortec heads, GMPP intake, maintaining the TBI setup. But I want to run exhaust manifolds. Manifolds should be less likely to leak, and I am not really looking for huge gains in performance. Plus I am hoping I will have less work on the rest of the exhaust if I am routing the same as the factory.

I have a 95 and am hoping to keep the front accessory brackets the same (the two big aluminum brackets). I think you are correct about the GMPP intake having a hole to mount the bracket going straight back behind the idler pulley. I was hoping I could bend the other brace to fit on one of the vortec intake's front driver side corner stud (simular to the factory setup). I know the TBI and vortec intake bolt paterns are not same, and that might not be doable. If that does not work I thought I could put two studs on that corner of the intake and bolt a rail across the them. Then bend the brace to an angle that would intercept the new rail, and bolt it to that. At least that is my current plan.

Not sure if I should avoid hanging a lot of weight on the intake bolts/studs, but I might do the same on the other side. Maybe fabricate a long railing going all the way to where the frist brace mounts to the two rear intake bolts/studs. My goal is to roughly keep a factory looking install with the MAP, EGR Silanoid, ESC, etc. in a simular location. That way I wouldn't have to cut on my wiring harness and I could route it the same as factory. I don't know why, but one thing I am disappoint with is the GMPP intake does not have the brake boaster port in the same location as the OEM. It shouldn't be difficult rerouting.

Of course this is my current plan. We will see what happens when I actually start getting everything back together.

A few question:

I thought I would be able to use my factory exhaust manifolds. But I think someone on this thread said that the tpi manifolds will not work. Why? It is just a standard SBC bolt pattern, right? Are they just too restrictive (smaller ports)?

Was the EGR system on the vortec engines external routed to the intake? Is that why you should switch manifolds with the vortec heads?

This is an additional vehicle for me, and I will not have a lot of time to dedicated to getting the job done. It will be a slow process for me, but I look forward to you updates.