TBI equipped Vortec Questions

[Jerrys1990]

Reading a lot here and on other sites, but still confused. Over the next year, I'm planning to install a low-mile $250 junkyard Vortec long block in my truck (1990 C1500 2WD) and keep all of my TBI stuff on it for simplicity. Everything will be stock...I'm not interested in headers, bigger cams, or whatever. I like the idea of the Vortec heads and factory roller cam for obvious reasons. I found a good deal on the GMPP intake too, but if it's gone before I can get it, I'll use a Vortec carb intake with an adaptor plate. Other tidbits I'll be adding include a Vortec fuel pump, and an adjustable FPR on a rebuilt throttle body. 3 wire o2 is going in tomorrow. So even though the long block will be stock, I'll still need a custom chip burned to take advantage of the more efficient Vortec design? Or will it run good enough to get me by? What is the best way to go about getting it tuned if it needs it? I am NOT fuel injection tuning savvy in the slightest, so all this talk about get this connector and this software and start data logging/burning chips is way over my head. This is also my daily driver so excessive down time is out of the question. I live in mid-Michigan if there's any old skool tuning folks in that area. I'll be honest, though I'm a 20 year auto mechanic veteran, this F/I tuning stuff makes me want to just toss a carb on it :/ I also considered a self-tuning stand alone system like a Fast or Terminator, but....more wiring, and more expense. I'm a fan of the TBI....cheap to fix, and it's truthfully all I need in this application.

 

[Komet]

If the TBI is all you need, find a low mile TBI longblock and then it's simple parts replacement. You can't have the cheapest, simplest, most powerful stock setup that only demonstrates the problems you want to solve. DynamicEFI sells a nice ecm setup that reuses the stock harness and would make any tuning changes needed easier to accomplish.

 

[Jerrys1990]

If the TBI is all you need, find a low mile TBI longblock and then it's simple parts replacement. You can't have the cheapest, simplest, most powerful stock setup that only demonstrates the problems you want to solve. DynamicEFI sells a nice ecm setup that reuses the stock harness and would make any tuning changes needed easier to accomplish.

I hear you, but, I'm interested in the Vortec for the power gain. It just appears to be a little more complicated than I initially though. I won't rule out a fresh TBI long block though....I'm sure it'd feel stronger than my current 204K mile oil burner.

 

[Erik the Awful]

You can run a Vortec longblock with a TBI adapter on a Vortec "carburetor" intake. A TBI adapter will fit a spreadbore intake much better than a squarebore intake.

Just remember that the water pumps are different. The TBI water pump shouldn't be used on the Vortec block without drilling the coolant bypass in the heads and block.

If the TBI is all you need, find a low mile TBI longblock and then it's simple parts replacement.

L05 cam specs: .382/.402" lift, 165.9/174.8° duration at .050", 111.9° LSA
L31 cam specs: .414/.428" lift, 191/196° duration at .050", 111° LSA

The stock TBI cam is laughably lame. If you're buying a junkyard motor, why not just aim for a Vortec from the start?

 

[Jerrys1990]

You can run a Vortec longblock with a TBI adapter on a Vortec "carburetor" intake. A TBI adapter will fit a spreadbore intake much better than a squarebore intake.

Just remember that the water pumps are different. The TBI water pump shouldn't be used on the Vortec block without drilling the coolant bypass in the heads and block.


L05 cam specs: .382/.402" lift, 165.9/174.8° duration at .050", 111.9° LSA
L31 cam specs: .414/.428" lift, 191/196° duration at .050", 111° LSA

The stock TBI cam is laughably lame. If you're buying a junkyard motor, why not just aim for a Vortec from the start?

Erik, I read a lengthy post last night where you showed pics of all that. The info was excellent. I guess you'd use the head gasket as a template to drill the holes? There were other things I questioned but that's another post for another day. Yes, the TBI is pretty lame. Merging on the freeway is frustrating sometimes It sounds like it's going to need some kind of tune no matter what. OldSkool EFI was talked about a lot....sounds like the way to go for tuning? I sent an e-mail to Harris Tuning also, and then began to read not so good things about his chips....

 

[Erik the Awful]

I guess you'd use the head gasket as a template to drill the holes?

Yes, but I haven't done it. I'm running the Vortec water pump, which required some creativity with the coolant hoses.

 

[Jerrys1990]

Yes, but I haven't done it. I'm running the Vortec water pump, which required some creativity with the coolant hoses.

I saw your solution to that. For the record, I'll be running as much of my TBI stuff as possible to keep the budget in check.

 

[L31MaxExpress]

You can run a Vortec longblock with a TBI adapter on a Vortec "carburetor" intake. A TBI adapter will fit a spreadbore intake much better than a squarebore intake.

Just remember that the water pumps are different. The TBI water pump shouldn't be used on the Vortec block without drilling the coolant bypass in the heads and block.


L05 cam specs: .382/.402" lift, 165.9/174.8° duration at .050", 111.9° LSA
L31 cam specs: .414/.428" lift, 191/196° duration at .050", 111° LSA

The stock TBI cam is laughably lame. If you're buying a junkyard motor, why not just aim for a Vortec from the start?

Specs on the TBI are flat wrong. Stock TBI 350 truck cam is 194/203 @ 0.050, 0.390/0.410 and 112 LSA, it used the uber basic 40 year old base HP small block cam.. There is not a GM small block camshaft anywhere even close to those specs. The smallest cam used in a SBC is the LG4/L03 305 cam. It is 178/194 @ 0.050 on a 109 LSA with 0.350/0.385 lift.

This same wrong information has been floating around for years. I degreed 3 different TBI engines and they were all 3 right what I was expecting them to be, the same old GM 929' cam that came in the older base 283, 307, 327, 350 and 400.

 

[Jerrys1990]

Specs on the TBI are flat wrong. Stock TBI 350 truck cam is 194/203 @ 0.050, 0.390/0.410 and 112 LSA, it used the uber basic 40 year old base HP small block cam.. There is not a GM small block camshaft anywhere even close to those specs. The smallest cam used in a SBC is the LG4/L03 305 cam. It is 178/194 @ 0.050 on a 109 LSA with 0.350/0.385 lift.

This same wrong information has been floating around for years. I degreed 3 different TBI engines and they were all 3 right what I was expecting them to be, the same old GM 929' cam that came in the older base 283, 307, 327, 350 and 400.

Wow...tiny tiny. Thanks for the clarification. Being a 1990, what are the chances that my block for sure has the bosses for the roller cam spider and the roller cam retainer plate? I ask because I saw a 1992 truck engine on Marketplace that didn't have the spider bosses at all. My understanding is, all the TBO truck blocks have the bosses, but some are tapped and some are not. Maybe his engine wasn't what he thought it was, or replaced with another at some point. Just curious.

 

[L31MaxExpress]

Wow...tiny tiny. Thanks for the clarification. Being a 1990, what are the chances that my block for sure has the bosses for the roller cam spider and the roller cam retainer plate? I ask because I saw a 1992 truck engine on Marketplace that didn't have the spider bosses at all. My understanding is, all the TBO truck blocks have the bosses, but some are tapped and some are not. Maybe his engine wasn't what he thought it was, or replaced with another at some point. Just curious.

Definitely false. I had a block cast in 1995, from a TBI Yukon that did not have the bosses as all. The block had the partial vin stamp for that Yukon on it. I have seen blocks without provisions at all, some that were not machined including tall lifter bores, some that were roller ready and others with OE roller cams. I was surprised when I opened the OE GM 350 TBI in my uncles 94 with him to find it was already roller cam equipped. I have also found several other TBI trucks and vans in the wrecking yard with what I assume were factory roller cams. The blocks had the partial vin stamp matching the vehicle and were roller. Nobody in their right mind puts a roller cam in an otherwise stock TBI 305 G20 for example, unless that cam went flat, but I doubt that was the case on an 8 year old van 20 years ago when the oils were still decent.