4.3L to 5.3L

[Dark Knight]

Looks like we don't have one of these in here yet, so lets start one!! Besides that, recent events are making it look like this may be the route I go. I know that my shop knows all about what to do... but I sure as hell don't. So people, lets assume that you got something with a 4.3L and you just happend to come across a 5.3L with all the accessories, wiring harness, and computer. My questions are:

How do you mate the old and the new? I can't find companies that talk about anything.... harness mods or otherwise.

What needs to be beefed up? New radiator, fuel pump, wha?

Simply does any of you super knowlegable people know anything about this? I may not be doing the work but I would still like to know about it. Might help me realize the cost of all of this.

Oh and as always... thanks for tollerating the n00b questions!

Mike

[DemoN]

i'm going to be doing this soon, so i am also very interested in what is needed.

Do i need a new radiator?
new fuel pump?
Will the existing power steering pump work?
Will the existing a/c compressor work? knowing that the location is different, is it the same physical part?
i don't have a wire harness from the 5.3L...do i need to get one and graft it in or can i get a painless kit?

[Dark Knight]

Well looks like no one has any opinions on this. Oh well, I got the engine and in a few months it will be in the truck. So I guess we will just have to make it up as we go.

[GMCwantsLS1]

I have an opinion! I bet you will have to make a custom harness, mounts ect.
You probally can't reuse anything as all the 4.3L parts are more likely to be found on a 350 than a LS1. So I would say you will need:
A new radiator
a new fuelpump
power steering pump
AC compressor
Wireing harness
mount adapters
maybe a custom oil pan
headers
Like I stated this is an opinion but I bet someone has done this swap before. I used to scan the search engines and check every website I could to find potential problems when I did my research.

[Dark Knight]

OOOOOO.... someone replied!

Actually I have been doing a lot of searching during what little free time my 70 hour work weeks give me. I have found some evidence of people considering this swap and a company that makes the pieces to swap it into old school full size chevys, but that is about it. I do believe that I will be the first lifted ZR2 Blazer to be running a 5.3.

Oh and I got a 2000 5.3 motor with all the accessories, the wiring harness, the computer, the headers, and the y-pipe... so that should help me out some.

[BigBlue]

Heck, with all of that stuff, it should be pretty much plug and play.

[Dark Knight]

I don't know about plug and play but it will be as close as I can get. And heck I got that motor shipped to my shop for $1080, so I couldn't pass it up.

[DemoN]

my research shows that the power steering pump is reusable, but you will need new radiator, fuel pump, water pump, a/c compressor, a/c hoses, and starter.

[Dark Knight]

Yep, that was pretty much what I was guessing.... more fuel and more cooling. AC is always nice too.

Maybe one of these days I will know exactly what it takes to get this done so that I can finally post some useful info.....

[severed ties]

street and performance has your motor mounts.