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How to swap a Vortec 350 into a 4.3 S10/Sonoma

272329 Views 210 Replies 56 Participants Last post by  Rhotpursuit
Doing a little write-up while it is fresh on my mind. This will be specific to 2000-2003 s10 with the 0411 silver computer and 2wd......but a lot of info will cross over into other years.

First, the engine:

You want 1996-2003 350 out of a full-size truck or an express/savanna van. If it is out of a 2500 or larger pickup, you must change the oil pan to 1500. It will not clear the cross-member.

Things you want to do before install to the 350:

Well, make sure it is a good engine. If it has too many miles on it, I will rebuild it just for peace of mind, even if it is a good running motor. You do not want to be pulling this motor again in 20k miles.

AT THE VERY LEAST, change the intake gaskets.

I would also recommend changing the spider injector to the updated version.

Check the distributor gear for wear and the shaft for side-to-side play.

Change the water pump. They are $40 for a brand new one. Again, peace of mind.

PAINT IT. This will make it look much, much better when installed.

Things you will need before you start this:

Motor mounts.
Many different companies make them, including JTR and Current Performance. I went with the JTR.

Four options here. Hedman, Sanderson, eBay stainless.....all shorties. Or, if you dare(you will have to move your fuel lines), long tubes. I used the Heddmans. You have to specify bigger flanges with the heddmans. They come with 2".

Most people use the 1986-ish Corvette radiator. This requires cutting on the core support. And requires an adapter for the lower radiator hose. I used the stock 4.3 radiators. I figured if I had to cut, I might as well make my stock one work. That way, I could use the stock tranny cooler and oil cooler. There are other options that do not require cutting. Current Performance makes one that fits in the stock location. But it was 500 bucks. I will post pics of the stock radiator frenched later in this post.

I used the stock clutch fan that was on my 350. My 350 came out of 1996 2500HD. You may want to go with an electric fan...I will be later when money allows.

Here are the electric fan options.
Using the stock radiator(16x26 inches), a 2000-ish Dodge Intrepid fan will fit PERFECT. And I will keep it cool. Also only pulls 14-16 amps. Also, a mid 90's Volvo fan will fit perfectly.....but pulls around 40-50 amps. You can also use an early-mid 90's Nissan Quest fan. It fits like stock and pulls only 20 amps.

If you go with the Corvette radiator(16x23 inches), your options change. A ford Taurus fan fits it perfectly. The 1995 and below single fan dual speed ones. You can also mod the Nissan Quest fan and make it fit.

The biggest thing to remember here is 1 or 2 aftermarket fans without a shroud WILL NOT COOL IT WITH AC. You must run a shrouded setup to get maximum airflow over the radiator.

AC condenser.
No matter what, when you move the radiator forward, your stock condenser will not work anymore. Some people modify the hood latch bracket and move it to the front of the core support. Another option is the Current Performance one. It will fit behind the core support.

With a 2000 and up, you can use your factory 0411 computer. It will need to be reflashed. Many places do this. I tried Wait4me and got screwed. It did not work. Engine only ran on five cyl. I now have a Current Performance computer, and it runs great.

Companies that do this:
Current Performance
Black Bear Performance
And many others...

From 2000-2003, use your 4.3 harnesses. You only have to add the two injector wires, a one-wire knock sensor, and separate the low side ground for the O2 sensors. I will get into wiring specifics later.

The 4L60E will work fine. I am sure the 5-speed will work fine too. You will have to get different bell housing bolts. The 4.3 are metric, and the 350 are not.

The stock 4.3 starters will work fine on either flexplate as long as the 5.7L was from a 1500 truck with 4L60e. My engine was from 2500 with 4L80e, so I could not use the flex plate. Again, the bolts on the 4.3 are metric, and the 350 are not.

OK......next post will concern installation. More to come.
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What if I have 4WD? Can I keep it? Certainly would like to:D
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