Ok here is goes..this might bore some folk...2003 Blazer 4x4 4Dr L3U engine
1) IF I needed to swap another motor in the blazer, what years block could I use?
1a) What vehicles?
2) IF said block where found, can I use the existing upper intake system?

V-8 SWAP
1) IF I wanted to do a V-8 swap, what years block could I use?
1a) What vehicles?
2) Would I use the same motor mounts(new of-course)?
2a) What exhaust system and exhaust manifold would I use?
2b) What part of the ECM, PCM..ext, would be need from the V-8 donor?
2c) Could I use the existing transmission and torque converter?
THANK YOU for any input, Tony

 

OK - you walked into this one and truly asked for it ...... Why are you now replacing the engine that you've been running 15W40 in?

I (and others) know the answers to your questions, but I think you first owe the Captain a sincere apology for your "Masser" comment in the oil viscosity thread. Can't have it both ways.

Probably Worx can answer all that you want to know, but I doubt if he will be inclined to help anyone in a significant way.

 

LMAO>>>Lesmyer..If I am ever in your part of town, Im going to buy you a beer or coffee, you comment made me laugh...My 2 part question was for informational purpose only...Knowledge is power!..Its because of this group that my Blazer is running like a "well oiled machine" and STRONG!..and the "Masser" was for fun only...but you gotta know me to get my humor.....so no punt was intended to anyone...I'm on the same team, Les!..Soooo, back to the question at hand...Can anyone answers these questions?

 

If you are keeping the standard V6, the only real change between 1996 and the end of production for the s-series trucks/suvs/vans that would disrupt a full remove/reinstall type swap concerns the knock sensor. Your engine has a bolt on knock sensor that uses a metric bolt (M6?). The 2001? and older engines have a screw in knock sensor that uses 1/4" pipe thread. An adapter could be made that would have 1/4" pipe on the bottom & an M6 threaded hole on the top to allow for the use of an older block in a newer application.


Concerning the V8 swap, I did some research on this a LONG time ago when I had a 2000 Bravada. The Vortec 5.7L (350) v8 (RPO code L31) found in the fullsize trucks/suvs/vans from 1996-2002 (truck applications ended in 1999) is basically the 4.3L with 2 more cylinders. The accessory drive mounting locations and most of the sensor locations are the same as the V6. With the Vortec 5.7L, wiring is pretty minimal as it would only need the wires for the additional two injectors be added to your harness and extend a few wires to reach the new sensor locations (or just use a harness from the donor vehicle and modify it to fit your engine bay as needed). The PCM should be able to be programmed with a V8 program that would work with the rest of your setup or you could have the V8 PCM programmed to work with your BCM, etc. The transmission will bolt right up. I am not sure on the motor mounts or manifolds. Jagsthatrun.com has a lot of information (and a book) on V8 S10 swaps that will cover these details.


Here are a few wiki articles concerning the 90deg V6 and the small-block that will shed some light on your options as far as years/makes goes:
General Motors 90deg V6 Engine
Chevrolet Small Block Engine - 350


Also, here is an article on the changes made to the 4.3L block through the years. It was written in 2000 so it doesn't cover the change that I mentioned, but it is good reading:
Rebuilding the New Chevy 262 by Doug Anderson - Enginebuildermag.com

I had purchased an FSM from a 1999 Silverado back when I was looking into this and I had an FSM for my 2000 Bravada. I would recommend having a factory service manual for both your truck as well as the donor truck to help blend everything together properly.


On the wiring, there are companies out there that will modify your harness for you. I can't recall them off hand, but I am sure that Google will turn up the relevant information.

 

I've got a '99 Yukon with a strong 5.7l. It is my tow vehicle, so the thought had crossed my mind to put a 383 in the Yukon and then transplant the 5.7 into my '02 rwd. Then reality set in and I realized I'd likely have two vehicles that don't run

 

You want the PCM programmed as an express van preferably same year as your blazer. This way other things work. Stock mounts don't work. Use your 2003 harness