late 90's vortec 3500 ?s

[no1udknow]

I'm sure someone has done this swap. Ls packages are fantastic, but also spendy, how different is the vortec 350 block from the older 350 sbc's I feel like these engines are readily available everywhere, I can pick up a late 90s tahoe for under 1000, and my 96 tahoe seemed to have a lot of power. any input is apreciated thanks.

[no1udknow]

side note, I was reading about the vortec 5700 (350) on wikipedia and started laughing when I saw this little tidbit....

Special applications

Oscar Mayer Wienermobile

[dubds10]

The nice thing about the '90s Vortec engines are their heads and roller rockers. Great to build up for power and easily carb'd if that's what you plan on doing instead of running all the computer stuff.

[MARKDTN]

Yes, you can do this.

5.7Vortec/4L60E or 4L80E harness are available from places like Street and Performance or Howell. You will have to have your PCM reflashed. Use the Vortec belt system and alternator. Find a compressor delete if you aren't going to have a/c. Should bolt right in and use standard mounts and exhaust, also hoses and fan shroud should work although it is a "long" type water pump.

The weekend after I put the Tuned Port engine in my '83 K20, I drove a '99 3/4 ton GMC and am pretty sure it had more power than my swap I just did. Have to be careful about intake leaks. The later were better, but there are issues with intake leaks on these getting water in the valley which can be detrimental. I think '96-97 are particularly bad about it. Anything I bought, I would put intake gaskets just to be sure.

[57taskforce]

I think you mean roller cam. I'm quite certain the l31 never came with roller rockers from factory. Roller rockers came with the Ls motors. The vortecs are certainly much closer to the small blocks we all know compared to the Ls motors. Inu opinion they are super reliable. Most of them have gone well past 200000. The electronics are still somewhat simple and the parts are available and relatively cheap. They have a few quirks like leaking intake gaskets but they are a good cheap option for a swap. Like any other original style small block look for worn bearings, blown head gaskets,etc.

[Nitis]

Fwiw. I'm pretty sure the vortec 5700 is one of the first LS that was a 5.7 l like from the gto vette etc

You are referring to the L31 the knock on them has been the injection style I'm not an expert so don't ask me for specifics. Also some claim the heads to be on the weak side but they do produce flow for sure. One perk people like is the one piece rear seal

I'm sure 15 years ago this was a much more popular swap but the LS is so much more readily available. But not practice in all applications like my 72 4x4 requires some extra effort

I'm seriously leaning towrds a stand alone TBI myself for pure simplicity.

[dubds10]

Originally Posted by 57taskforce

I think you mean roller cam. I'm quite certain the l31 never came with roller rockers from factory. Roller rockers came with the Ls motors. The vortecs are certainly much closer to the small blocks we all know compared to the Ls motors. Inu opinion they are super reliable. Most of them have gone well past 200000. The electronics are still somewhat simple and the parts are available and relatively cheap. They have a few quirks like leaking intake gaskets but they are a good cheap option for a swap. Like any other original style small block look for worn bearings, blown head gaskets,etc.

Yup didn't catch myself there lol Roller cam not rockers.

[57taskforce]

Originally Posted by Nitis

Fwiw. I'm pretty sure the vortec 5700 is one of the first LS that was a 5.7 l like from the gto vette etc

I've always understood the Vortec designation to be a truck thing as far as I'm aware(even though the Ls car and truck motors are pretty much the same with small changes like intakes and such). At least on the late 90s stuff I know it's true. The cars had the Ls1 but I don't remember them being called a vortec 5700. Are the current car motors called vortec 5300 or similar depending on displacement? I genuinely don't know because I'm into stuff that's 15+ years old for the most part.

[57taskforce]

Originally Posted by MARKDTN

Yes, you can do this.

5.7Vortec/4L60E or 4L80E harness are available from places like Street and Performance or Howell. You will have to have your PCM reflashed. Use the Vortec belt system and alternator. Find a compressor delete if you aren't going to have a/c. Should bolt right in and use standard mounts and exhaust, also hoses and fan shroud should work although it is a "long" type water pump.

The weekend after I put the Tuned Port engine in my '83 K20, I drove a '99 3/4 ton GMC and am pretty sure it had more power than my swap I just did. Have to be careful about intake leaks. The later were better, but there are issues with intake leaks on these getting water in the valley which can be detrimental. I think '96-97 are particularly bad about it. Anything I bought, I would put intake gaskets just to be sure.

I would say the difference in the power you felt is the vortec heads ability to generate low rpm torque. That's kinda where they are the happiest. The don't flow near as well at high rpms in my expierence.

[dirtyjim]

actually the best donors come from 2001-2002 express vans. they used the 5.7 vortec with a 411 ls pcm. you can use the stock vortec central port inj or repin it for individual injectors and run a tpi style intake or a ramjet with a ls throttle body.
I'm collecting the parts to do mine now.

[Eddie H.]

As mentioned, the L31 vortec engine has many desirable features like a roller cam and one piece rear main seal. The swap is easier than with an LS engine, because except for the front serpentine belt accessory drive setup, the L31 is basically the same as the 350 that came in these trucks originally. They did have a problem with intake gaskets leaking coolant into the crankcase and wiping out the bearings and the "poppet valve" style injector spiders also gave some trouble, but can easily be upgraded to a spider that uses individual injectors.

[no1udknow]

Originally Posted by Nitis

Fwiw. I'm pretty sure the vortec 5700 is one of the first LS that was a 5.7 l like from the gto vette etc

You are referring to the L31 the knock on them has been the injection style I'm not an expert so don't ask me for specifics. Also some claim the heads to be on the weak side but they do produce flow for sure. One perk people like is the one piece rear seal

I'm sure 15 years ago this was a much more popular swap but the LS is so much more readily available. But not practice in all applications like my 72 4x4 requires some extra effort

I'm seriously leaning towrds a stand alone TBI myself for pure simplicity.

Yeah, I know about the spider injection system and it's flaws, had that problem on my tahoe. they weren't too bad to change. Anyone souped one up, what kind of power have you gotten out of it?

[no1udknow]

Originally Posted by Eddie H.

As mentioned, the L31 vortec engine has many desirable features like a roller cam and one piece rear main seal. The swap is easier than with an LS engine, because except for the front serpentine belt accessory drive setup, the L31 is basically the same as the 350 that came in these trucks originally. They did have a problem with intake gaskets leaking coolant into the crankcase and wiping out the bearings and the "poppet valve" style injector spiders also gave some trouble, but can easily be upgraded to a spider that uses individual injectors.

thanks for the input. I have been racking my brain over an ls swap, but the cost point and the amount of work involved in the swap alomost makes it not worth while. My tahoe had tons of power top end as well as some grunt, but I'm sure that could be adjusted through the various cams available for that motor. As far as the injector and intake issues go, I imagine someone makes aftermarket everything to solve such issues. I want good power, with fuel injection, and a good tranny and it seems the only way to get that setup is with a newer engine setup.... but I can't afford the ls option, at least not for a while.

[Nitis]

If you don't mind me asking what's your budget? And what's it going in? Sure you can get late 90s tables for under a grand but they're pretty used up over 200k on the ticker right?

I just abandoned the thought of doing an LS swap on mine mainly because it's a 4x4 requiring crossmember swap and suspension lift. All things that kept stretching the required budget not really out of reach but to the point it would take me longer to finish the project than I wanted.

When I do add fuel injection down the road it will be tbi I'm almost certain unless I stumble upon some I found wealth

I passed on a wrecked 2003 tahoe 5.3 with 150k for 1300 the other day. If I had a 2wd I would have found my donor

[87Skier]

They are very similar. I just did this swap on my 72 GMC Jimmy since it needed a motor anyway. I liked the idea of having a carburetor, older style HEI, and running without a computer. If you go this route the setup is nearly indistinguishable except to the keen observer.

Some key differences, some already listed, one piece rear main seal, different timing cover, timing chain is a single roller (makes room for the crank angle sensor in timing cover), roller cam/block, and no where for a fuel pump in block, different valve covers and geared starter.

When I did my swap I bought a 97 Suburban for $600, threw on some new parts and it went right in. While I was at it I decided to do a bunch of other extra work. I swapped to an electric cooling fan (I think you can use the mechanical even from the new engine), used the new power steering pump (just swap the fittings from old pump to new style pump), and some other stuff.

This is my L31 swap

[Nitis]

Of course if your going carbed no quirks no frills like the guy above 87skier

[Nitis]

I think isn't there something to do with e reverse water pump or something ?

[87Skier]

If you follow the serpentine routing vs the old v belt routing the pump does indeed rotate in reverse direction. You can put any water pump you want on there, but the accessories have to match.

I'm not sure about no quirks or frills. Easier to troubleshoot in my opinion and no reflashing computer for stuff that isn't there.

[Vintage Windmills]

Originally Posted by dirtyjim

actually the best donors come from 2001-2002 express vans. they used the 5.7 vortec with a 411 ls pcm. you can use the stock vortec central port inj or repin it for individual injectors and run a tpi style intake or a ramjet with a ls throttle body.
I'm collecting the parts to do mine now.

Good info. Can you elaborate on how to run individual injectors and where to get the parts to do the swap?

[mechanicalman]

Originally Posted by Nitis

Fwiw. I'm pretty sure the vortec 5700 is one of the first LS that was a 5.7 l like from the gto vette etc

You are referring to the L31 the knock on them has been the injection style I'm not an expert so don't ask me for specifics. Also some claim the heads to be on the weak side but they do produce flow for sure. One perk people like is the one piece rear seal

I'm sure 15 years ago this was a much more popular swap but the LS is so much more readily available. But not practice in all applications like my 72 4x4 requires some extra effort

I'm seriously leaning towrds a stand alone TBI myself for pure simplicity.

The L31 heads got a bad rap for being weak and cracking IMO because people were installing them without any t-stat bypass hose. They simply do not have that hole drilled to match up with the block and when installed without a bypass hose the coolant does not circulate until the t-stat opens and sits there and burns atop the cyl head creating steam pockets and eventual overheating and cracking.

I like your idea for the stand alone TBI. The wide band O2 systems are great and somewhat self programming.

Have you seen the stand alone fuel rails for the LS engines? Simply elegant.

[mechanicalman]

Originally Posted by no1udknow

I'm sure someone has done this swap. Ls packages are fantastic, but also spendy, how different is the vortec 350 block from the older 350 sbc's I feel like these engines are readily available everywhere, I can pick up a late 90s tahoe for under 1000, and my 96 tahoe seemed to have a lot of power. any input is apreciated thanks.

The vortec 350 block is practically the same as any 87-95 block it's just a 1pc rear seal roller cam capable, some 2 bolt main and some 4 bolt main.

87-95 heads are different, swirl port heads that are only good for lower RPMs. 86 SBC is old non-swirl style perimeter valve cover heads with 1pc rear seal flat tappet only and pre 86 is old style perimeter valve covers and 2pc rear seal flat tappet only.

Are you thinking of using the entire engine fuel injection, 4L60E and the computer system?

Or going carburetor but keeping the vortec block and heads?

[Mock1]

Just rebuilt a 2001 vortec 5.7 4 bolt main from an express van. Converted it over to carb. Rotating assembly measured to specs, even the rings were good. But, the cam bearings were shot.
Things to change if converting to carb...
1.Timing set, comp cams has a setup for this swap. Two row timing chain, cam gear that will fit the roller cam and clear the block, and a new crank gear.
2. Timing chain cover. The fuel injection cover has cam position sensor in it, is a one peice plastic P.O.S. Just replace with the old school one piece stamped cover. I got mine from Pep Boys and it came with the crank seal installed. Oh, you will have to add two 1/4" dowel pins in the block for the cover to line up cause the factory cover has them in it.
3. Intake must be changed.
4. Might as well change the oil pump while your at it. Cant remember what the tube size difference is now. High volume is larger than the stock replacement, but dont remember specifics.
5. Everyone and thier mother will tell you the gear on the distributor needs to be changed for the roller cam, horse puckey, unless your distributer has a BRASS gear, you dont need to change it.
6. Beware of using a 5.7 from a 4X4 as those heads will be of the swirl port type, great for low end torque, suck for higher rpm horsepower.
7. You will need an electric fuel pump, regulator, and a gauge to set the proper pressure as the vortec blocks aren't machined for a mechanical pump.
8. Spec a harmonic balancer for a 90s camaro with a 350, thats what I used.
That's about all I can think of. Good luck.

[MARKDTN]

Originally Posted by 57taskforce

I would say the difference in the power you felt is the vortec heads ability to generate low rpm torque. That's kinda where they are the happiest. The don't flow near as well at high rpms in my expierence.

Yes, but low end is where a Tuned Port shines as well. I am really happy with my TPI. The visual of a TPI is the best of any small-block ever IMHO and they are quite reliable.

I hope the OP is going to keep the injection and electronic transmission. I would not go to the trouble of putting one in without fuel injection. One of the reasons the fuel injected engines go so many miles is that you aren't getting as much fuel in the oil as a carbed one.

If you do carb it, I would be cautious of the advice above. The Vortec heads will only stand so much cam without some machine work. The valve springs will bind. You really should get the right distributor gear, or you may have trouble. '90 Corvette and '90 IROC Camaro are 2 different IDs on the gear. One or the other should work. I am unaware of any differences in heads between 4x4 and 4x2 applications.

[Mock1]

Originally Posted by MARKDTN

If you do carb it, I would be cautious of the advice above. The Vortec heads will only stand so much cam without some machine work. The valve springs will bind. You really should get the right distributor gear, or you may have trouble. '90 Corvette and '90 IROC Camaro are 2 different IDs on the gear. One or the other should work. I am unaware of any differences in heads between 4x4 and 4x2 applications.

I was only stating my experience with what ive done, not what he should do. I also stated the rotating assembly speced out, so I used the stock cam, standard bore block with stock rings, and stock pistons.
I have two different distributers, factory HEI, and a MSD Pro Billet, both gears were IDENTICAL to the gear Summit sold me for a roller cam. And it wasnt for a corvette or a camaro.
Ive opened six 4x4 350s in the past year and they all had swirl port heads, maybe a fluke, dont know. I just assumed they all were. My bad.

[57taskforce]

Originally Posted by MARKDTN

Yes, but low end is where a Tuned Port shines as well. I am really happy with my TPI. The visual of a TPI is the best of any small-block ever IMHO and they are quite reliable.

I hope the OP is going to keep the injection and electronic transmission. I would not go to the trouble of putting one in without fuel injection. One of the reasons the fuel injected engines go so many miles is that you aren't getting as much fuel in the oil as a carbed one.

I agree 100% the tpi motors are very Purdy! They were certainly the bees knees in there day. Also I would keep it efi as well. If you run the 0411 PCM there's a lot of potential for tuning and more power.