[71Formula]

I have thrown a rod bearing in my 71 Firebird 400 and now I'm debating on what to do. I've found a low miles 2002 Chevy 5.3 Liter Fuel injected motor with a 700R4 tranny with computer and wire harness for a very reasonable price (2k). Would this be a very good engine in my 3600 lb Firebird (less weight than that without the Pontiac block in there)? Has anyone done this? If not the 5.3, how about the 6.0L or 8.1L? I'm just considering this to build a good reliable streetable car with decent gas mileage. My Pontiac 400 is rebuildable and I am not by any means apposed to building it back up. But, the modern EFI with overdrive is for some reason appealing. Any suggestions, comments?

[hugger]

The 8.1L is just the latest big block chev. the 5.3 -6.0 are the ls based motors and are becoming more common place as a swap. There are many companies that offer swap parts. I am nearing the end of my swap on my 6.0 lemans convertable. This swap is not as difficult as you might think but you need to consider,fuel, engine wiring and pcm. if you need help Imight be able to help you since I just came from there. jim.

[71Formula]

Thanks Jim, I've got some questions for you; Are you using an original engine computer from the 6.0L or did you do something different? What are you using for a fuel pump since the fuel injection needs high pressure? What are you using for a transmission?
Thanks... Roy

[hugger]

Roy, I used the drivetrain out of a 02 c2500 suburban that was rolled over . It has 17,000 miles and I used the engine [6.0L] and trans[4L80E] the acc.and the pcm. I used the wiring harness that came on that motor but had it reworked to eliminate the emissions and provide a better tune for a little performance. The pcm is also out of the sub reworked by the same guy. I put a electric pump from a 96 chev truck in a caprice tank to fuel my car.Some of the people that have done this swap in a chevlle say that the truck acc. wont fit but, I used the stock acc. drive[even a engine driven fan] stock oil pan and intake. I made my own mounts and have room everywere that it is needed. I think you would really love the ls motor in your car. Next week I hope to maybe drive the car all I am missing is my shifter[coming from e-bay] driveshaft[alum shaft I'm having cut down to fit] bleeding the brakes[changed to 4wheel disks] and havingthe pipes hooked up. jim

[71Formula]

Wow that sounds great. I'd like to see some pictures, if you have some you can email them to me at [email protected]
Excuse me for a sec while I ask a stupid question. What is the acc drive?
Roy

[hugger]

Roy, the only stupid questions are the ones not asked. The[acc.] drive is the alt, ps pump, water pump and a/c compressor. I have some pics but I am afraid they are not very good. jim

[71Formula]

I appreciate the help Jim. Who did you have rework your wiring harness? And if you don't mind me asking how much did it cost? The more I read on this and look into it the more I like it.
The Engine I can get is out of a 2002 Chevy P.U. and the tranny is a 4L60E out of a 2WD P.U. I've heard a little about the truck engines being taller (intake and ACC I believe). Do you know much about that and did you do anything to change it or was it even an issue?

BTW, I found some of your posts on LS1tech.com Very informative site, I will likely talk to you there too.

Thanks again for the help. Roy

[hugger]

Roy, I sent my wiring harness and pcm to SPEARTECH. John was an electrical engineer for gm for like 35 years. He did what he said he would do when he said do at the cost he quoted me. I found his work to be top notch. The wiring harness rework and pcm tune ran 750.00. The intake off of a truck is taller than that of a car but I had no fitment problems there.This swap is costly but I feel it is worth the cost to have late model dependability in a old car package

[Skip Fix]

The 5.3 in my wife's Avalanche feels pretty peppy in it, pulls her horse trailer easily also so should power the Firebird OK.

[Pontiacmuscle]

Not to HiJack the Post but Im wondering how different a Duramax would be....like maybe in an old '56 GMC?

[RamAirZ]

Originally Posted by Pontiacmuscle

Not to HiJack the Post but Im wondering how different a Duramax would be....like maybe in an old '56 GMC?

Alot different, your talking completely different fuel system, injector pumps, etc. More of a PITA. Can be done but not as easily as these LSx swaps. I've already been through my LSx swap once and it was pretty easy.