Semi-complete Vortec swap

[benjaminearle]

So i just bought a '79 with a known cracked (and JB welded) block. Supposedly it's holding but that won't do in the long run.

Vortec 350s are popping up cheap, and dressed (i need a compressor anyway) and i'm wondering...

It appears, based on other postings, that the exhaust manifolds should bolt up so we're good there.

I understand I'll need a $200 edelbrock intake manifold to convert the FI to carb (good, new, Edelbrock carb, i think, on the truck currently - hope that will swap over)

The alternator isn't a problem, just a pinout to solve.

So that leaves, i think 4 questions:

1)Bellhousing - Will the Vortec bolt right up to my TH350 with the existing TC?
2)Motor Mounts - Do i need anything goofy?
3)AC Compressor - I will just assume that GM changed fittings somehwere between 1979 and the Vortec era - can a hose shop just make those hoses up for me reasonably?
4)Ignition - the big one - Do/Can the Vortecs run distributors or MUST i run some sort of ECU for spark?

OK, a 5th (of Turkey, pleasse)

5)Any specific years to look for that make any of the above easier or harder?

My hope, of course, would be to find a $300 dressed engine and find out that i can just drop an intake on it and everything else will bolt up, and deal with the AC lines when it gets warmer.

What say the experts?

 

[Jims86]

So i just bought a '79 with a known cracked (and JB welded) block. Supposedly it's holding but that won't do in the long run.

Vortec 350s are popping up cheap, and dressed (i need a compressor anyway) and i'm wondering...

It appears, based on other postings, that the exhaust manifolds should bolt up so we're good there.

I understand I'll need a $200 edelbrock intake manifold to convert the FI to carb (good, new, Edelbrock carb, i think, on the truck currently - hope that will swap over)

The alternator isn't a problem, just a pinout to solve.

So that leaves, i think 4 questions:

1)Bellhousing - Will the Vortec bolt right up to my TH350 with the existing TC?
2)Motor Mounts - Do i need anything goofy?
3)AC Compressor - I will just assume that GM changed fittings somehwere between 1979 and the Vortec era - can a hose shop just make those hoses up for me reasonably?
4)Ignition - the big one - Do/Can the Vortecs run distributors or MUST i run some sort of ECU for spark?

OK, a 5th (of Turkey, pleasse)

5)Any specific years to look for that make any of the above easier or harder?

My hope, of course, would be to find a $300 dressed engine and find out that i can just drop an intake on it and everything else will bolt up, and deal with the AC lines when it gets warmer.

What say the experts?

Assuming you are talking about the gen1 vortec (96-2000) everything will bolt up once you have the Vortec specific manifold.
Carb, electric fuel pump, Distributor....and make sure you use 96 or newer listings for spark plugs.....vortec specific. As far as accessories, you can re use all the 79 v belt stuff, make sure you use the 79 water pump.

 

[benjaminearle]

Is there any reason NOT to use all the serpentine accessories on the 96-00 engine? I'm currently short one AC compressor, so if i find a dressed engine with a compressor, I'm money ahead to use it, right?

 

[Jims86]

Is there any reason NOT to use all the serpentine accessories on the 96-00 engine? I'm currently short one AC compressor, so if i find a dressed engine with a compressor, I'm money ahead to use it, right?

Sure, you can use the vortec stuff. New AC hoses can be made no problem...i was not sure if you had a complete vortec.

 

[adriner]

Assuming you are talking about the gen1 vortec (96-2000) everything will bolt up once you have the Vortec specific manifold.
Carb, electric fuel pump, Distributor....and make sure you use 96 or newer listings for spark plugs.....vortec specific. As far as accessories, you can re use all the 79 v belt stuff, make sure you use the 79 water pump.

If I'm not mistaken vortec heads are reverse flow (correct me if I'm wrong, that may just be on the tbi engines) so why would you want to use the 79 water pump?

 

[bucket]

Is there any reason NOT to use all the serpentine accessories on the 96-00 engine? I'm currently short one AC compressor, so if i find a dressed engine with a compressor, I'm money ahead to use it, right?

The problem is getting a used compressor that doesn't have leaking case seals.

If I'm not mistaken vortec heads are reverse flow (correct me if I'm wrong, that may just be on the tbi engines) so why would you want to use the 79 water pump?

In a serpentine belt setup, the water pump pulley spins backwards which is why you need a reverse rotation pump.

 

[Jims86]

Yeah, surpentine pump turns the other direction. LT1 heads are reverse flow.
The vortec heads are just regular SBC heads, with the LT1 runner and chamber design

 

[HotRodPC]

If I'm not mistaken vortec heads are reverse flow (correct me if I'm wrong, that may just be on the tbi engines) so why would you want to use the 79 water pump?

I think you meant Vortec Water Pump here, not heads. Yes, you're correct. If he goes with the serpentine set up, MUST use that water pump off the Vortec motor. Also if using the Vortec AC compressor, I'd flush the AC lines, evap and condensor, and convert to R134a Freon while at it.

 

[benjaminearle]

What's the deal with the 88-95 engines? Are they not nearly as good or something goofy about them that makes them not worth swapping in? I'm seeing some of them out there too listed as Vortec. $500 with all accessories and computer and harness.

 

[HotRodPC]

In the 88-95 motors, they are TBI throttle body injection. In 96 they are Vortec and SFI, Sequential Fuel Injection. I think it's 50 more horsepower with the 96 to 99 motors, then onto LS 4.8/5.3 motors.

 

[Jims86]

What's the deal with the 88-95 engines? Are they not nearly as good or something goofy about them that makes them not worth swapping in? I'm seeing some of them out there too listed as Vortec. $500 with all accessories and computer and harness.

87-95 truck engines(as well as the TBI cars) had heads with swirl port intake ramps that promoted torque and fuel economy, but did not breath well enough for higher rpm ranges(camaros wer high geared) as far as performance.

 

[benjaminearle]

OK, so in my situation, where my main concern is an easy replacement for a cracked-block engine, anything 87-00 will be fairly simple and gain some improvement in power and economy over the original LM1-ish 350. Obviously the SFI Vortec L31 will be better than the TBI L05.

What kind of HP/Tq numbers are people seeing with stock L31 or L05 engines with the carb conversion and how does that compare to:
1) the stock FI numbers and
2) the old LM1 numbers?

Thanks,
Ben

 

[Jims86]

OK, so in my situation, where my main concern is an easy replacement for a cracked-block engine, anything 87-00 will be fairly simple and gain some improvement in power and economy over the original LM1-ish 350. Obviously the SFI Vortec L31 will be better than the TBI L05.

What kind of HP/Tq numbers are people seeing with stock L31 or L05 engines with the carb conversion and how does that compare to:
1) the stock FI numbers and
2) the old LM1 numbers?

Thanks,
Ben

It really depends on what you want to do with the truck.
Stock gen 1 vortecs 350s were rated at 255hp and over 300 ft lbs(not sure of the exact number),keep in mind, those rating are with SEFI, where fuel control and atomization are more precise.
Wha ever you use for induction, will be an improvement over what you had....ma ybe in the hood of 40 hp, and moe torque to match, but maybe at a higher rpm.You will also benifit from the roller cam as well.
Would also be good to replace the oil pick up tube befor you install the engine too...stocks have been known to fail.

 

[HotRodPC]

Why am I thinking the first 96 350 Vortecs were putting out 285hp? I know I can be wrong, I bought so damn many brand new trucks from 93 to 2004, I could be easily confused. I had 3 different 93's, 3 different 95's, 4 different 96's, one being a Ferd I6/5Speed. So I could be lost in there.

 

[Jims86]

Why am I thinking the first 96 350 Vortecs were putting out 285hp? I know I can be wrong, I bought so damn many brand new trucks from 93 to 2004, I could be easily confused. I had 3 different 93's, 3 different 95's, 4 different 96's, one being a Ferd I6/5Speed. So I could be lost in there.

255 in 96, 350 final production.