LT1 into a '89 Firebird

[cheronobyl]

Hello all, I'm new to the site, came over from 3rdgen.org, was looking for more help on an lt swap and rebuild

So, background info. I popped the v6 that was originally in the car. After a little bit of searching I found a fourth gen equipped with an lt1 for 400. Naturally it had a blown head gasket. Setting that aside, I went out and bought a t56 from a 97 Camaro that also had an LT. The guy gave me the PCM with it.
The current plan is to rebuild the lt as a stroker, bore it, port and polish the heads, then drop the whole thing into my 89 body with the T56 transmission and the 2.73 rear axle off of the fourth gen. I am trying to do the swap on a budget but understand that this is no cheap endeavor. I will also be using the stock LT wiring harness, the stock 3rd gen K-member, the 4th gen plastic tank/fuel pump, and the stock 3rd gen interior if possible.


Now is the part where i need help. I need advice on engine rebuilding, info on the "A/C notch" (I live in Vegas, A/C is necessary) and anything else you would deem useful. I will check this thread at least once a day and be sure to post any pictures and give consistent updates. I hope to eventually clean this up and make a new sticky-able thread to replace a lot of the ones we have lost. I'd appreciate some subscriptions as I will need a lot of help. This isn't my first engine swap but it is my first non-stock swap. The same goes for the rebuild.


TL:DR I am doing an entire 4th gen drivetrain swap into a 3rd gen.

[popo8]

Well...welcome to the site bud. Im def not the guy to tell u how to do the swap... But we have a large amount of members that are.. JCZNova... Into a nove...rx7...2 monte carlos... A 3rd gen camaro....

LTXtech.com is my DRUG!

[JCzNova]

:welcome_ltxtech:

We have a few that have done the 3rd gen swap as well. muddyjimmy Ryan Stout

[Injuneer]

Welcome to LTXTech.com!

As an aside, why a 2.73 rear with the T56? The 94 and up T56's have a 2.66 first gear, and two steep O/D ratios (6th is 0.50:1). The 94 and up T56 came stock w/ a 3.42 rear. Many people opt for 3.73 or 4.10's. Huge pull of the line and low cruising RPM. I had 3.73's in my 94 when it still had the original T56 and I wished I had gone for the 4.10's.

Also be aware the 4th Gen 10-bolt rear is 3" wider than the 3rd Gen and will require that you run large positive offset wheels to keep them under the fenders.

For the T56 install, check with Steve Spohn at Spohn Performance. I loaned him my spare T56 about 14 years ago so he could develop a kit to install it in a 3rd Gen. Not sure if he still makes the kit though.

[79LT1Monte]

Welcome to the site, lots of good information on here and great people.

[DMBlack]

Welcome to LTxTech. I am also on TGO under the same screen name.

The LTx third gen swap is pretty easy and well worth the effort. Ask away with any questions you may have.

As for the A/C notch, I did not keep A/C so I did not need to do that. I think there are some threads with this info on TGO.

I swapped to the fourth gen fuel tank but mine was a metal tank. I did have to shorten the filler neck to get the fuel door to close. I just cut a 2"-3" section out and spliced it together with some universal rubber filler neck hose from NAPA and some clamps.

I first swapped in the fourth gen rear differential but later went back to the third gen because of my wheel choice for the drag strip. I will be swapping in a fourth gen 12 bolt so I will have to change wheels to keep them under the fenders. Along with Injuneer, I would also suggest going with a 4.10 rear gear with the T56. The 2.73 gears will not work well with the double overdrive in the transmission. I have the feeling you will find it bogging down on the highway and having to downshift when you get to hills. This will only get worse when you add an aftermarket camshaft where low rpm driveabilty suffers.

Again, welcome to the forum and keep us posted with the project progress.

[cheronobyl]

Sorry to have let this thread die for a short bit. The 3rd gen was originally a v6 so the diff I have from it is an open, which is terrible. I'm not exactly sure what you mean by positive offset, so if you could explain more it would be great. Also the diff came from a 95 automatic. I bought the t56 separate because I prefer manual. Sorry for the late reply, I had finals week and had to give it a break for a bit. Also, on my plans for a rebuild, I could use some recommendations on kits, cams, and other such things.

[Injuneer]

Positive offset on the wheels means the backspace of the wheel is very large, compared to the "frontspace". That way, the wheel works with a wider rear axle assembly. Most of the wheel is projecting into the wheel well, and there is very little "lip" on the front of the wheel. I run an 11" wide wheel on my 4th Gen, and this is an extreme example of a large positive offset, resulting in a large backspace, and very little "lip" on the front of the wheel.

[cheronobyl]

I probably will buy a 4:10 rear end eventually, but for now I will probably run with what I have to cut costs a bit. I have the 4th gens rims, if I used those will they fit under the fenders?

[cheronobyl]

Unless you guys can show me towars a decently priced better rear end. I live in Las Vegas, NV, so if you know anyone, send them my way.

[Ryan Stout]

How did I miss this? WELCOME

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