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4.3 TBI to 4.3 carb swap

  #1  
Old 02-13-2019, 09:31 PM
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Default 4.3 TBI to 4.3 carb swap

I currently have a 2000 Blazer, about 210,000 miles. Engine is on its way out, so I was considering an LS swap. Turns out, the LS swap would just be a little too expensive for me at this point. So, I did some hunting and came across an engine builder who has a 4.3 from around the same year (he said 2000 to around 2003.) Got a screamin' deal on it, rebuilt with a little extra beef. The one difference is that this motor is set up to run a carb (the only part I need to buy to make it go vroom).

I'm not the most mechanically inclined person, but I'm confident that I can pull this swap off with (hopefully) a set of helping hands. To me, it seems like this should be a fairly straightforward process, unbolt/unplug old motor, yank it out, get the new power plant in place, bolt it up, plug it in and burn some rubber (definitely over simplifying).

I talked to my sister's husband (mechanic) who told me the hardest part will be setting my truck up to run a carb. Again, I'm not the most mechanically inclined person, but isn't the function of a carb to basically use mechanical (read: non-electrical) methods to dump gas into the engine? More oversimplification on my part but my sister's husband said its basically down to "gutting the fuel pump and wiring the truck up".

He and my sister are having a baby, probably this weekend, which is when I hope to start the swap, so I won't really have him around to help.

My questions are:

1) How complicated is the wiring process, and does anyone have any experience with this part?
2) What needs to be done to the fuel pump in this swap?
3) The guy who is selling me the motor said something about an "MEI" distributor, and that I would just have to "run one wire", not sure exactly what he said because I spoke to him as I was walking into class. Any ideas here? I'll be speaking to the guy again and will ask him, but I would like to hear feedback from this group as I'm sure someone can elaborate on this.
4) While I have the engine bay empty, what should I take care of? You know, kinda like if you have the trans out to change the clutch, might as well check out the slave etc...

I'm hoping that this setup is a simpler setup than the current 4.3 I have. So many wires and sensors and things to go wrong.

Any information, warnings, advice, that anyone has in this endeavor would be GREATLY appreciated!
 
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Old 02-14-2019, 01:22 PM
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Fuel pump to a low pressure set up and.dist. to a HEI and it may kinnda run and that's the easy part.
Most of your electronics will not work, gauges will not work, computer will not work, ECT ECT ECT
What you are trying to do is not for the novice as it's not even close to a plug and play swap.
 
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Old 02-14-2019, 07:06 PM
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If it's an automatic, the trans probably won't work, either, right? In addition to all the other stuff mentioned

Also, how is the engine "set up to run carb?" seems to me you could just pull the FI intake manifold off your old engine, and put it on the new, and call it good.
 

Last edited by cleburne red; 02-14-2019 at 07:09 PM.
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Old 02-14-2019, 07:46 PM
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Mine is currently a manual, the intake manifold is what I'm having problems with along with a cylinder that keeps losing compression.

The new motor is set up to run on a carb as in it has an Edelbrock intake with a 4100 Holley four barrel flange. I want to eliminate all the computer crap, can't I just run fuel and spark and make it work? Obviously the gauges will need to be addressed, but what is the need for the computer if there is no electronic injection going on?

I recently put a TH350 into an old Jeep that is running a carb'd 350 that has such a simple set up...no computer, minimal sensors, minimal wires, and it runs like a top. Is this application really that much different?

These are genuine questions, as I said before I'm not the most mechanically inclined person. I guess I should rephrase that, since I am mechanically inclined but am not experienced with big jobs like this.

Here are some pictures for reference:




 
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Old 02-14-2019, 08:03 PM
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Basically this is a bad a$$ motor that I found by total chance at the exact right moment. The guy who built it has been building race motors for about 50 years and he is now retiring and closing up shop. This was his personal motor for his rat rod, he did all the machining himself, its a complete fresh motor; new bearings, roller lifters, new pistons, fresh cylinder walls (.030" over), timing set, cam...everything internally is new, balanced, and assembled by a life long, old school gear head. I couldn't pass up the opportunity to have something like this in my Blazer. Not only is the LS swap too costly right now, everyone is doing it. I know this won't make nearly as much power as say a sweet 5.7, but this motor is something you just don't see every day. At least I haven't seen many beefed up 4.3's besides a few on youtube.
 
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Old 02-14-2019, 08:48 PM
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Computer controls more than just fuel injection, and spark.
And yes it's a lot different than having a 350 and adding a th350 trans in a old non computer operated jeep
However your not going to be talked out of this set up so just be for-warned nothing that has anything to do with the computer is going to work.
You will be rebuilding each system in the vehicle into a non computerized system.
If you have the time, money, and knowledge any thing can be done.
Proof of that is in my avatar
 
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Old 02-14-2019, 09:04 PM
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What systems are we talking here? I'm not trying to come across as a know it all dillhole, but I am just not one to give up when something is complicated.

As long as I have speedo, tach, oil pressure, temp, voltage, lights, brakes, power steering...I'm good, right? I'm sure I'm missing things, but my point is that I'm fine with basic functions.
 
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Old 02-14-2019, 09:35 PM
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Originally Posted by JoshyB View Post
What systems are we talking here? I'm not trying to come across as a know it all dillhole, but I am just not one to give up when something is complicated.

As long as I have speedo, tach, oil pressure, temp, voltage, lights, brakes, power steering...I'm good, right? I'm sure I'm missing things, but my point is that I'm fine with basic functions.
Well the only basic functions that you will have is power steering and maybe headlights, brakes if ABS don't screw with you.


 
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Old 02-14-2019, 09:36 PM
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Originally Posted by odat View Post
Well the only basic functions that you will have is power steering and maybe headlights, brakes if ABS don't screw with you.
Will the existing gauges hook up similarly in the new motor? I feel stupid admitting it, but I'm not sure which are monitored electronically and which are mechanical.
 
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Old 02-14-2019, 11:58 PM
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Originally Posted by JoshyB View Post
Will the existing gauges hook up similarly in the new motor? I feel stupid admitting it, but I'm not sure which are monitored electronically and which are mechanical.
None are mechanical.
I'm not trying to talk you out of the build.
But in-less you rewire thu out the whole vehicle the computer can never be totally removed and as systems are intertwined you have the risk of failure of systems.
If you remove all the unneeded systems and had the computer re-flashed to remove all unneeded programing you may end up with a trouble free vehicle.
 

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