SuperMacDaddy

I just picked up an 86 with the Carb'd LG4 and auto trans last night. I have a guy offering to sell me a complete LT1 350 TPI out of a 96 for $300, or the complete TPI setup for the 305 for $100. How much trouble is swapping in an LT1 vs converting to TPI?

Drew

iTrader: (58)

LT1 and TPI are mutually exclusive terms. 85-92 long tube EFI = TPI. Opti-puking short runner reverse cooling bastard gen II SBC = LT1.

Converting a carbed car to EFI is silly. Either way you're talking about a wiring nightmare, and changing the entire fuel system. To do it right you pretty much need a running EFI car to cannibalize. On the other hand, if you stick with the carb it's a matter of taking any carb and a HEI, and hooking up less than half a dozen wires.

five7kid

iTrader: (14)

Agree, don't refer to LT1 as "TPI". It's an insult.

I have no problem with the LT1 family of engines, especially '95-up with the active vented Optispark. I have a '96 Vette with LT1, it's a good-running and reliable engine. I even had a water pump failure right after I got the car (water pump bearing was shot - I think the seller knew that and didn't inform me). The Opti got soaked, I just wiped it dry when I replaced the water pump. That was over 3 years and 16k miles ago, it hasn't missed a beat. The LT1 is a fine engine.

As for swapping a carb'd car to EFI, I wouldn't bother with TPI. You can get a factory carb'd engine to run very well (which I have done), although you may not quite meet the TPI fuel efficiency. If you set everything to factory specs, do a little secondary rod tuning, improve the exhaust (the factory exhaust is very restrictive) it will run quite well, even with a healthy 350.

As for swapping a factory carb'd car to LT1, I can support that. It'll be a bit more work, but the results will be worth it. You'll need an in-tank electric fuel pump, exhaust upgrades as mentioned above, and if you want to keep AC you'll have to notch the K-member, but you'll be pleased with the results. More details about the work involved are in the LT1 swap sticky in the top section of this forum.

I've swapped two carb'd 3rd gens to LS (plus a '57 Bel Air), so I can vouch for it being worth it. I first considered LT1, figuring it would be a little less work, but settled on the LS1 as it is overall a better platform.

Summary: Pass on the TPI. Go with the LT1 (assuming "complete" means with harness and PCM) if you're up for the work. An LT1 4L60E would be better than your TH700 (in more ways than one - no TV cable mount on the LT1 throttle body is one good reason). You will need to disable VATS in the PCM.

jakemussman

iTrader: (3)

I would go with the LT1 over a 305 any day. Don't fear the optispark, they get a bad wrap from people who don't know how to properly diagnose electrical systems. Being a '96 it will already have the better vented version. If you are paranoid there are some mods you can do like drilling and tapping the weep hole on the water pump. This allows a length of vacuum hose to be attached, routing any leaking coolant around the opti. I daily my LT1 in snow and rain (which we get a lot of) and have never had an issue.

Flycaster1977

iTrader: (1)

Im almost ready to drop my lt1 into my 87 iroc, originally an lg4 car. Im just waiting for the block to get back from machining.
Overall the swap isnt hard at all. My car was ac delete so i just pulled the ac stuff off the lt and no need to notch the k member.
You will have to get a fuel sending unit from a tpi car and fuel pump and then fab some fuel lines. I went with the braided stainless. I had a member here, pocket, make my swap harness because of the time involved, but doing the wiring yourself is fairly straight forward.
If you are going to the expense of going efi, then look hard at the lt1. If not then just keep it carbd, but i wouldnt waste time on the 305. You will spend just as much as you would to build a 350 and have much more power.

silvvette

Lt1, all day long. Did the same with my vert:
http://www.cardomain.com/member/bluepastu/

Was awesome swap with a t5. Now doing the same lt2 into an 81 vette with t56.

best motor for the buck!

HyperFlyer

Agree with the lt1, doing mine now. Wiring isn't fun but you could stay carb and go lt1. They have an intake that allows you to use a carb and hei instead of opti. All you would need is starter and tach. Just keeping the options open

tglennon11

iTrader: (2)

Congrats on the purchase!

I have to agree with five7kid (not the first time in one of these threads) LT1 over TPI if you are doing EFI. The LS platform is still superior, but could leave a bigger hole in your pocket. Bang for the buck if you are willing to get dirty lt1 is pretty hard to beat.

if you don't want to mess with EFI get a 5.7 vortec pull out of a truck edelebrock intake and carb and you set. I'm not sure I can get behind the work involved to convert the lt1 to carb when the vortec motors are available.

disjaukifa

Also a vote for the LT1, just helped my friend do one and it's a beast of a motor, great power and fuel economy for a V8, I'd so go with the LT1 over the 305 any day!

Street Lethal

iTrader: (16)

There's really nothing magical about this anymore. Once upon a time, yes, when varying intake manifolds like the HSR, SuperRam, MiniRam were all the rage, members would argue which is better; 305 vs 350, TPI vs LT1, etc as they had graphs to back them up with different camshafts and valve events. Bottom line is an engine is an engine, give it what it wants. If the 305 is in good condition; good oil pressure, good compression, then just stick with it. Both engines are essentially cast from the factory so neither can take that much abuse anyway, so it boils down to how much power you're looking to throw at it, and at what power band. For $100 I would buy that TPI setup in a heartbeat mainly because they are more tune friendly, especially since you can utilize the LB9 wiring harness to work with an EBL Flash system, or even any of the stock ECM's and varying codes like the Super $8D, $59, etc with a few simple pin moves. The LT1 would require you to run a Megasquirt if you want to tune it, or another costly system that also controls the optispark, the stock OBD1 systems cannot. This isn't to say that an LT1 is a bad engine, it most certainly isn't. It's just not drop in. A lot has to be changed to accommodate it, including your detent cable for the trans if auto...