StealthElephant

So I just found out that someone I know has an entire 94 LT1 computer/ignition setup. He bought a complete LT1, got rid of the stock FI and put on an aftermarket direct ignition system.

So lets say I can pick up all the LT1 stuff for basically nothing. I pick up an LT1 long block w/ intake for almost nothing at a junkyard. Get a custom LT1 harness made for it. What else am I missing? Am I going to have compatability issues with using a different year block? I think I read the water pump drive gear changed from 94 to 95? He uses the eletromotive direct ignition. I have no idea what he didn't use, he just said everything for the LT1 that he didn't need, is sitting in a box, including the stock injectors, and that if I want it, that I can have it. Now, I'm guessing that he took all the sensors (MAP, MAF, O2, etc etc). I have no idea how long that list is. How much am I looking at to replace the sensors and such. Assuming he has all the core components (which I have no idea, but I'm assuming he has the PCM and such). I mean, I've seen LT1 long blocks for like 500$. Factor in like 500$ for a harness, I get the computer for like 50$. How much am I looking at to complete the system? Am I going to nickel and dime myself to death getting the sensors and such. Most complete LT1's I've seen are like 1500-2500. Just wondering, because I'm fairly sure it was a 94 LT1, and from what I've read thats one of the more desirable years. When we took his LT1 apart, he still had the optispark on the engine, it wasn't being used, but it was on. That doesn' t need to go back on correct?

I don't have the 1800$ to just go out and buy an LT1, but I KNOW I want my 2nd engine to be an LT1. So I figured if I could come out somewhat even peicing it together it wouldn't hurt. Plus, if the missing sensors and such are not TOO expensive, it wouldn't be bad to have all new sensors going into the engine. If I can get the LT1 computer stuff for almost nothing, I might as well.

TexasLT1

It could be one of two things, an incredible deal, or a money pit from hell. The sensors overall shouldn't be too much, except for the MAF sensor which runs about $200. Everything else is pretty reasonable, I believe. As far as the optispark goes, you can take it off and throw it aside, just make a block-off plate for the timing cover. The easiest thing to do would be to leave it on the engine though, its not taking up and room and wont cause any problems since it's not being used.
The most expensive thing is going to be the wiring harness. It will definitely cost in the $500 region unless you can find a used one (not likely) or find someone who could do it for you.
Oh yeah, and the waterpump drive gear situation wont matter unless it is missing from the block, then you would want to get the correct one.

StealthElephant

Thats what I was thinking, I just ordered "How to Rebuild Small-Block Chevy Lt-1/Lt-4 Engines" by Mike Mavrigian, I should get in on like monday or tuesday. How many sensors does the LT1 use? O2, Map, MAF, and what else would I need to replace? I was actually thinking of making my own wiring harness, assuming I could get the connectors.

My only concern is that I get the computer from a 94', the intake off a 96, the long block off a 97, and the sensors off a 95, and it won't go together, then I will have wasted money. Were there any changes to the intake manifold over the years due to emissions adjustments?

TexasLT1

That will work just fine what you are talking about doing. Manifolds stayed the same, no changes at all.

Sensors/Electrical Connections (off the top of my head)
-IAT
-MAF
-MAP
-Knock
-Oil Pressure
-Oil Temperature
-Coolant Temp
-IAC
-TPS
-O2 (2)

I may have missed one or two, but I think that covers most of the electrical connections to the computer other than the obvious ones like fuel injectors. That is all of the sensors, but you may not need them all depending on what is still on the engine. I would definitely NOT suggest making you're own harness. That would be a nightmare in itself unless you have a LOT of time, patience, and electrical skill. Besides the fact you will spend a fortune on connectors alone. Granted its from GM, but all I got were MAF and A/C compressor clutch connectors and those 2 alone cost $44. I would strongly urge you to consider getting a harness made from someone who has made a lot of them and knows what they are doing. Then again, thats just me. If I do another LT1 swap, I may consider making my own harness now that I know what I'm doing so that I can make the harness cleaner and mount the computer anywhere I like.

StealthElephant

I've got all the time in the world....like you said, wire and time are not an issue, it's the connector cost that will be the deciding factor. Hmmm...I have my 87 TPI harness lying around, it's useless, and mangled, but all the connectors are on it, I wonder how many are the same as the LT1 if any (injector harness, O2 sensors, etc).

Thanks for all the info Texas.

LT1guy

iTrader: (1)

You've got the 94 computer (OBD-1), which is good. Make sure though that you use the proper knock sensor from the 94 (OBDII is different). 94-97 all the intakes are the same; 93 is different, and is said to not flow as well. Be sure also to use the correct length drive pin in the cam for the Opti you are using. If you stay with the 94 (non-vented) Opti, it should have the longer dowel pin. If its bad, try to get a later Opti and timing cover, they're more reliable and the Opti is a lot cheaper, too. As a note, if you run an electric water pump, the drive won't be an issue and you can use a much cheaper timing set for a factory hydraulic roller cam small block.

StealthElephant

Well what I'm wondering is, if I get a random year LT1 block, and put an aftermarket roller cam in, I can have the neccesary pin intalled?

Dave Y

actually, the non-vented optis use the short dowel, the 95-97 use the long

TexasLT1

As long as its an LT1/4 cam, the pin is no problem. But definitely try to get a 95-97 opti, they are MUCH better than the 93-94. If you do get the 95-up opti, you'll need the longer dowel pin.

LT1guy

iTrader: (1)

Sorry about that, you are correct...brain fart!

LT1guy

iTrader: (1)

Not necessarily. I bought an aftermarket cam that "appeared" to have the correct dowel pin, but it was actually a few .000ths too long and destroyed my Opti in a matter of minutes. Check it just to be safe. GM dealers have the correct dowel pins available.

TexasLT1

Really? What cam was it? I hadn't heard of that before. I knew being too short could obviously be a problem, but didn't know being slightly too long would be.

LT1guy

iTrader: (1)

It was a GTP-6, from Gallant Technical Performance. I don't blame them, though...just like any other precision item (esp engine parts), you should ALWAYS measure, check clearances, etc...don't "ASSume" its right. GTP was very apologetic, and I probably could have gotten them to do something for me, but I honestly felt it was my own fault for not measuring it to begin with.

TexasLT1

Oh ok. I guess I should have checked the length of the pin then in the CC306 we just put in my friends car...