Ok so my neighbor has a 1997 Suburban sitting in her drive way. I couldn't help but do some research and grabbed the vin from the vehicle and I found out it has an L31 which is the 350 vortec. I currently have a 91 z28 with the LB9 (305 TPI) and I was wondering if it would be possible to swap the motor in? Will the engine mount right up on the current mounts? Will it match up to my tranny which is the 4 speed auto that comes stock with the z28? Would it be better to use the setup already on the L31 in the suburban such as the distributor, intake manifold, etc.? Or could my intake manifold and TPI setup bolt onto the L31? I have never done a swap before and would appreciate as much info as possible. All information you have to offer will be of great help.

 

Motor bolts straight in

You wouldn't use the Vortec EFI so you need this aftermarket intake to put your TPI on the different Vortec heads

https://sdparts.com/details/edelbrock/3817

and get a custom tune on your computer

 

Ok thanks that makes me feel a lot better about the possible swap. So if I buy the baseplate then I can still use my stock ECM correct or would it be better to just use the ECM in the suburban. I would be able to buy the L31 completely dressed up so would that help out any or change anything else?

 

Again thanks for you reply all this information helps out alot! Plus I can probably get the motor with accessories for around $500 or less

 

Also would it be better to run the tpi setup or try and convert it to the TBI or Carb if I swap in the L31?

 

Keep it TPI. The L31 engine is a great shortblock replacement for our cars.

Keep your own accessories, and you'll need to change the front timing cover as well. You can use the heads from that engine, or get a different set of heads, or even keep your 305 heads. But if you keep the Vortec heads, remember they dont have EGR passages, and you'll need the different intake manifold to bolt up to them as Vetteoz said.

 

ok that makes me feel alot better now. I guess all that's left is to go over to the neighbors house and see what kind of deal I can work out. Thank you very much I appreciate all the help. If I have anymore questions I'll definitely ask

 

My suggestion would be, keep it EFI; but NOT TPI.

There is exactly ONE TPI intake base that will fit Vortec heads; the one vetteoz linked. It is $$$$super expensive$$$$$. Its performance is uniformly described as disappointing. Even to get it up to the level of mere "disappointment", it requires ALOT of money.

I'd recommend some one of the aftermarket FI setups. The most cost-effective one right now seems to be the HSR. http://www.summitracing.com/parts/wnd-7542/overview/ It's cheeeeeeeper than that TPI base (by the time you overcome some of the limitations of the TPI long runners), and will run circles around it. It's not "The Fastest" out there, but it's OK; and for somebody that isn't a hard-core hot-rodder and tuner, and that doesn't have to deal with California emissions which since you mention "carb" I'm going to make that guess, it's all-around a better way to go than TPI.

Custom tune goes without saying... even a stock motor benefits ENORMOUSLY from that. It would be BEYOND STUPID to buy a bunch of mechanical parts, and then NOT do the tuning work, which is basically the equivalent of all the carb and distributor tweeeking that has traditionally been necessary to really DIAL IN a combo that has "potential".

 

ok thanks sofaking. I'm still gonna see what kind of deal I can work out for the motor. Any suggestions on a price for the motor? I'm gonna try and get the entire motor with accessories and at worst turn around and sell the extra parts to make some of the cash back. Also would it be better to just use the injectors on the L31 still or swap in a set of new ones?

 

www.car-part.com

You'll understand better when you see the L31 up close; you won't be re-using that.

 

Ok got ya. thank for all the help

 

best way would be to sell the Vortec haeds get a set of pre 95 350 heads built up then use your complete existing system, with all of your 91 sensors / accessories and all. you would have a simple straight forward swap. the Vortec accessorie system "front of the motor" WILL not work with TPI see http://www.gmtruckcentral.com/articles/lt1swap.html I spent 3 months working on the accessories alone, this build is now 3 years old and still running

do not go carb!!! you will hate your self later, plus the hodpodge crap with the tranny

Also you will hear that the Vortec heads are worth 30+ hp over the old style heads, that is corect!! but a TPI runs out around 5500 to 6000 RPM, just when that extra HP is beginning to be made. so to us TPI advocates it is not worth the time to discuss it. Just My Opinion!!

 

I would ditch the TPI and keep the L31 heads, rather than the other way around.

Completely agreed about "not going carb" though; that's an even worse idea in the long run.

There is no wisdom or even common sense in giving up THE MAIN benefit of the L31 - its fantastic heads, as stock heads go - just to preserve an inferior intake system.

The Vortec heads plus the HSR is good for close to 100 HP over TPI.

Accessories are a non-issue in your case, although they might be in the case of someone who perhaps didn't have the L98 ones to begin with. You just take your existing ones off your L98 and stick em on your L31. No-brainer.

 

No matter what,stick with some sort of roller cam for that engine.The mere fact those L31's are a roller block and a roller cam engine from GM is the other part that makes them so attractive.
Before purchase,a compression check needs to get done.That is important.

 

Been working on something similar for a little while now...

Here are some notes that I made.

https://www.thirdgen.org/forums/tech...ads.html(notes about bolts & other stuff)
https://www.thirdgen.org/forums/afte...w-headers.html How to take off the spark plugs.
https://www.thirdgen.org/forums/engi...uirements.html
https://www.thirdgen.org/forums/tech...lt4.html(parts list for lt4 hot cam)
http://www.chevyhiperformance.com/howto/97458/
https://www.thirdgen.org/forums/engi...5-tbi-l31.html
https://www.thirdgen.org/forums/alte...ealth-ram.html

5)Camaro Accesories will swap over!
6)Avoid the EFI System from the vortec engine.
7)TPI Fuel Pump Will WORK!
8)Motor Mounts are the same

Walbro 255 pump
Rebuild Kit $500 (MKP6504000)
Stealth Ram $$379.97 (Part#7542)
Fuel Rails+regulator $259

If you want to go hotcam with the vortec & not machine the guides down...

lt4 Hot Cam=(JEGS)$211.99
LS1 Valveguide Springs=61.99 #809-12499224
Comp Cam Retainers 787-16 $53.99
Timing Chain CLO-9-1157 61.99 Might as well
Sealed Power Part # ST2015 $5

 

Thanks for the advice but I have an LB9 not the L98 sofaking. Don't know if that changes up anything though?

 

MMroc86 thanks for the help I will definitely take a look at al the links to see which route I wanna go. Just reading all this feedback makes me that much more pumped up to really go after this motor.

 

No; sure doesn't. The accessories are exactly the same, identical in every way.

Sorry about that.

 

So bad news the neighbor decided to fix her suburban and now I no longer can purchase the L31 damn definitely wanted that motor. My uncle has a sbc 350 that came out of a 1972 Monte Carlo. It's the 4bbl carb motor I think stock was rated at 175hp. Any thoughts on this motor and is it worth getting for like 100 bucks and rebuilding, or should I just pass and keep looking? Also would this even be possible to swap into my 91 z28?

 

Keep looking for a L31.

 

You can get a brand new L31 long block from GM for 1800 and change IIRC. Might be a bit out of your price range, but could be worth it in the long run.

 

Just keep searching CL & the JY's you'll find a vortec block, they are plentiful.

 

the best option if money is tight is to build the 350, put 27lb injectors in it, and a nice TPI cam and go. if it is your first project/rebuild start easy. and i still say vortec heads aren't the best. a vortec block would be nice "roller block" but the cam is $300 alone. P.S. you never said is your motor bad, or are you just wanting more power??

 

The motor I have right now is still good. Currently at 170K on odometer. I would love a nice vortec build but I can't afford a brand new one that's why I was hoping to get this L31 cheap. Plus I'm looking for something to work on gradually because this is my first swap/rebuild so I wanna get the experience and learn as well.

 

Don't take the 72 detour.

Keep your money in your bank account and let it GROW, until the thing you REALLY want appears. Don't worry; it will. Always does, sooner or later. Beats the crap out of buying something inferior, emptying your bank account, being disappointed in the results (as you will be with a stock 72 350), and then having no money to make it right.

Best option at the moment is to do NOTHING. Keep your money in your pocket. Don't "build" ANYTHING.

 

that is cool, take your time and have fun,

 

The 305 isn't that bad.... I've been DD my 86 with it for 10yrs now. Decent on gas & super reliable.

Save up ur $$$$! Go hard or go home!

 

Then it's decided! I'll hold off and just maybe add some headers to my camaro and a new set of tires and use it like that. Who knows maybe I'll just end up saving for an LS1 build in the future instead