new lt1 where do i start?

[Woodnears]

Scored a 95 lt1 out of a roadmaster. Picked up an a/c delete pulley. Trying to decide if and how to rework the harness. What can i do away with on the motor? Smog pump, o2 sensors, anything else? some one break this down for me please! I will send out the computer once i figure out what I'm getting rid of. Also any tricks for getting a manual Speedo for the 4l60e that's behind it?
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[Woodnears]

Oops i probably should of put this in the drive line column!
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[67c10rustbuket]

Check out lt1swap.com they have the wiring schematics and ecm pinouts with lots of info for your swap.

http://lt1swap.com/index.htm

[GMCJOE]

I did the conversion, only with a carburated intake. You could have the 02 sensors removed or keep them. Smog pump, get rid of it. The rest, I couldn't really tell you. I would just type in LT1 into the search portion of the site and you will find some build threads with them. Not a popular these days with all the engine advancements.

One tip, I do suggest you take the intake manifold off and have a hole machined in the rear to drop an HEI distributor in. Then pull your water pump and remove the Opti-Spark, buy a opti-spark delete plate from summit. This will save you some hassles later on down the road because of the opti-spark failure rate. Very common failure, and an easy solution. Good luck, looking forward to seeing a build thread.

[Woodnears]

Do I want to build a harness as a stand alone unit or do I need to keep something? I'm in the middle of tearing this thing apart right now. Lots of wires in here!
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[Woodnears]

I know this is old skool but someone please get me started.
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[GMCJOE]

It might be easier for you to buy a standalone harness if you don't know much about the wiring thing. Just search LT1 in the search part of the forum, even if it is an older truck that its being converted into. It may be a lot of help.

[6772owner]

I used the harness that came with my 96' LT1 and just removed all the wiring I didnt need. I downloaded wiring diagrams off of LT1swap.com, LS1tech forums and Corvette forums. I deleted the Smog pump, rear O2's (I was using 95' single cat headers so they werent needed), Evap Purge, etc Then I had the VATS and everything tuned out of the computer, you can get a mail-order tune for $150 or so with a power tune.

PM me if you need/want help with anything.

[Woodnears]

I guess what I am wanting to know is what basic components do I need to keep operational to have a running motor? What sensors are a must? That kind of thing? Do I need all the oil level sensors, knock sensors, temp sensors, and what have you?
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[GMCJOE]

The site mentioned before ( http://lt1swap.com/index.htm ) Gives you all the pin out removal info you need for what components you don't need to run.

[Dale99]

X2 on 6772 comment.

Must keep
TPS
IAC
VSS
ECT
left n right 02's
knock sensor
map
IAT
whatever it uses to know what position the engine is in(crank, cam, or both)
leave the coil obviously


delete
rear o2's and burned from pcm
oil level
anti theft and have it burned from pcm
oil pressure you could likely delete and use the original setup for the truck

[Woodnears]

Can I not flash out the o2 sensors?
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[Dale99]

You can the rears, but if you flash the fronts out, you will never get it to run right EVER. Might as well toss a carb back on it and throw the pcm in the trash.

Everything, and I mean EVERYTHING, on that pcm relies off the o2 sensors. They are the whole reason to go to a pcm.

[Woodnears]

Do I need any of the wires that would normally go into the firewall of the donor car?
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[Woodnears]

What is this connector for and can I remove it?
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[dukcaln]

some good info here

[Dale99]

Ive not fully dealt with an LT1. I did an L31. But that first one looks like the connector that is under the dash normally and gives the input to the cluster, ac, etc.

You need to have a wire diagram before you start taking things out/apart.

[6772owner]

I think (if I remember correctly) I used some (maybe all) of the heavy red wires inside the truck. I think they are constant power feeds that went to a fuse block inside the donor vehicle. I agree with Dale99, I would check everything before you cut anything. That large flat connector looks like it would go to a computer of some sort, but Im not sure, my harness was out of a Camaro so thats all Im familiar with.

[Jonboy]

I think I would do an aftermarket harness if you really are unsure. It will probably make the difference between really hating this project and really enjoying it. The new harness will have everything labeled as to where it goes or needs to be terminated.

I have had good luck with Robert at www.fuelinjectionconnection.com for harness work. A new stand alone harness and reflash of your PCM is probably going to be close to $500. To get the speedo to work you will either need to swap gauges and get an electric speedometer, or pick up a Cable-X box. Those are about $300 or so.

While you are removing stuff, I would suggest removing the EGR as well. Almost all of the LT1 cars I have had have had EGR issues. If you are thinking of running a HEI, that may be in the way as well. I personally haven't had any optispark problems, although some have. If you go with the later, vented version it cuts down on a lot of the moisture problems. Having teh engine out makes it a lot easier to swap in a new water pump and Opti as well.

The LT1 makes a pretty nice swap. I had one in a 79 SWB, and I really liked the way it ran. Good power, pretty good mileage, and the "gee whiz" factor when you open the hood were all good things in my book.

[MARKDTN]

I would buy an aftermarket harness, but if you do use the one from the car get a factory shop manual.

I would second leaving the O2 sensors, it will not run well without them. I would leave canister purge, wish I had on the TPI in my truck. I would definitely get rid of the air pump. I had 2 go out on the '96 Caprice with LT1 we had from new. It is in a bad place. The Corvette ones don't go out.

[Dale99]

As for egr. That would depend if he has emissions to deal with. If he does, he needs to leave it.

Even w/o emissions, after fully reading into what it does, I would leave it. I'm trying to figure out how to put one back onto my camaro since it has an 0411 swap.

[Woodnears]

Yeah I'm thinking about going to an after market harness. Just thought i would make an effort and possibly learn something new. I did delete all the extra smog and air pump stuff.
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[Woodnears]

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[Woodnears]

Has anyone used the harness from lt1harness.com? Looks good for the money.
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[GMCJOE]

IMO, I would do the stand-a-lone. Little costly, but at least you don't have to deal with the headache if you aren't good at wiring. I would seriously recommend machining a hole in the back of the intake and dropping a distributor. If you use a regular HEI, I would drop a MSD module in it. Or just get a MSD distributor with highout put. Of course that means getting a new balancer with the timing marks and a opti delete plate. Vent or no vent on the opti, it will fail much sooner than HEI. Plus, it is just a PITA to change out. I have changed way too many out for people. Makes for getting a good deal on a LT1 car though when the person can't figure out why the car doesn't start.

Run long tube headers that are recommended for the truck. The oval port headers work just fine on the D-Port heads. I tried block huggers at first. Passenger side hits on the cross member.

If I ever find a donor car for cheap, I will probably switch it over to fuel injection and put the T-56 in the truck.

Lots of choice's, ready to see your build thread.