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4.3l to 350 swap

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Old 03-04-2008, 01:05 AM   #1
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4.3l to 350 swap

ok i read this but i am confued a little

---------------------------4.3 TBI to 350 TBI----------------------------------
To make this easier, I’m doing a fuel-injected engine to a fuel-injected engine. Meaning there’s no need for gas tank modifications. If you go from carbureted to EFI, or vice versa then you need a new Gas tank unit for the appropriate method.
Your job is A LOT simpler in most cases. But don’t let that fool you, its still a chore to do.
If you have a 4.3EFI from 87-93 TBI and you get a V8 from that same time frame that’s TBI, you have little or no wiring issues. Everything that plugs into the 4.3, will plug into the 350. When we did mine, we used everything from the 4.3 on the 350, including Throttle Body, Power steering, Water pump, Harness, and computer. But if you have a vortec, and are switching out, you need to pull harness and computer, and you need a complete 350, as most parts wont transfer. So with that in mind, here are the parts lists -
THESE PARTS *NEED* TO BE REMOVED-
Engine.
(If 94+ vortec to any other 350, Harness and Computer)
THESE PARTS STAY-
Master Brake cylinder
AC/Heater boxes
Tranny
Drive train
Radiator (pull it to remove/install the engines though)
PARTS that will be *NEEDED* -
Engine
Engine mounts (See links at bottom of thread)
Headers (See links at bottom of thread)
Electric fans
Harness and computer (if 94+ swap)
***NOTE, when purchasing harness/computer or having a harness made, make SURE it’s for the proper Tranny and dash setup!!! Hate to plug it in, and not have it work!!! ****
Basically, its the same install path as the 2.2. Get your harness in, and computer, install the new engine mounts, then drop the engine in, plug it in, and install the headers. Put the radiator back in. Once again, I recommend the fans in front of the Core support. Get in and test it out. etc.
****For Both Installations- If you want the fan in FRONT of the V8, and behind the core support, you need to shorten the drive shaft, scoot the tranny back, pound some room on the firewall for engine tabs, and distributor clearance, and slide it all back on the Engine mount adaptors. Keep in mind, that makes it extremely hard to do menial tasks/tune ups, such as replacing spark plugs, installing new wires, and running the exhaust. ****
Now this was just a ROUGH sketch of a swap, and it answers most questions, with a few recommendations. Here are the links for the manuals, and parts -
JTR - lots of people use these guys
Advance adaptors, will have all your answers here too
Any MORE questions, post them in here, We'll be glad to help, plus this will clear out the clutter in the V8 forum, about everyone asking about swaps
Thanks guys, and many happy cylinders!



but one guy told me i could use the stock fan and the stock manifolds
also do i use the pulleys and stuff off the 350.
Old 03-04-2008, 02:35 AM   #2
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Re: 4.3l to 350 swap

I dont think stock manifolds will work too well. Late 80's camaro ones i hear work good. But id recommend shorty headers for ease of swap, hedman longtubes are the best, but a little more expensive (never used them though). A note, the longtubes need the 350 engine and frame mounts, and the transdapt conversion mount plates, also automatic tranys only.
The 350 tbi accessories should work, i think they are the same as the 4.3 tbi accessories.

A couple other things i see there. I hear pusher fans dont work near as well as puller fans. If you put your radiator inside the core support, it gives you plenty of room to use a normal elec. fan. No need to do any of what is stated there. I use a taurus electric fan and have my engine as far foward as it can be, and still have a little clearence between the water pump and the fan.

Another thing, id recommend using a late 80's corvette radiator, theyre all aluminum and thicker than the v6 one.

Also, i would use the v8 transmission, or have the v6 one rebuilt. You'll wear out the stock v6 one pretty quick if you drive it hard at all.

Last edited by bkaltec; 03-04-2008 at 02:49 AM.
Old 03-04-2008, 11:28 AM   #3
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Re: 4.3l to 350 swap

i used the camaro manis,the only thing on them when doing a tbi 350,the passenger side is VERY close to the wires that go back inthe cab.I guess the headers would make it worse as far as heat getting to the wires.....as far as the gas tank,if you are going to carb from tbi,you dont need to do ANYTHING to the tank,just leave the pump in there(but unplug it or cut the wires).when there is no power to it,the check valve stays open "meaning fuel will pull through the pump" when using a block mounted pump or whatever your using,no need to buy a regulator.done it several times
Old 03-04-2008, 11:31 AM   #4
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Re: 4.3l to 350 swap

one other thing,the pullys on the 350 and 4.3 are the same,I made a fan shroud out of the 4.3 shroud,used a clutch fan,with ac,never overheated.had the rad in the "forward" position.
Old 03-04-2008, 03:34 PM   #5
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Re: 4.3l to 350 swap

Ok some guy told me i dont have to buy v8 conversion mounts all i have to do is take the old mounts off and set the motor on the frame line it up and weld the mounts in and all i have to do is cut a little out of the fan sround on the bottom and the stock manifold will work.
Old 03-04-2008, 03:46 PM   #6
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Re: 4.3l to 350 swap

I dont see how that would work at all. The conversion mounts set the engine perfectly to where you dont need to do any driveline modifications. Permitted you use the right transmission (700r4, 4l60, th350 w/9in tailshaft, t5). And by the way it looks to me its far enough foward you wouldnt be able to weld the origional v8 mounts strait to the frame without some kind of extension plate. The conversion mounts are only about 60 bucks for a good set and save a lot of trouble and time.
And im sure you can make the stock manifolds work, but ive not heard of anybody using them without extensive modifications. Best bet is to find a cheap set of camaro ones if you dont want headers.
Old 03-04-2008, 04:48 PM   #7
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Re: 4.3l to 350 swap

ok thanks
Old 03-23-2009, 02:31 PM   #8
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Re: 4.3l to 350 swap

will a 1994 4.3 tbi vortec 5-speed trans mount to a 350?
Old 03-24-2009, 08:10 AM   #9
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Re: 4.3l to 350 swap

I have a 92 4.3 4x4 s10 and a shortblock 94 non vortech 350 tbi will everything from the 4.3 liter work on the 350 and is the 700r4 a good tranny or should i get a turbo 350 or even 400? The 350 is stroked to a 383.
Old 03-24-2009, 07:54 PM   #10
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Re: 4.3l to 350 swap

700 trans 87-92 they are the best ones to get
Old 03-28-2009, 11:58 AM   #11
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Re: 4.3l to 350 swap

Don't forget the correct injectors for the engine size as they are different. The EST module will need to be changed for the V8.
Old 04-08-2009, 04:15 AM   #12
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Re: 4.3l to 350 swap

will a 1996 4.3 computer work with a 350 vortec. i heard the 350 will plug right into the 4.3 computer.
Old 07-19-2010, 12:55 AM   #13
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Re: 4.3l to 350 swap

Yeah, my question is about the motor mounts, headers and oil pan. Will the 4.3 motor mounts be in the correct location? Do all headers have to wrap around the steering column as I've heard? And will the oil pan clear the front axle and everything else down there?
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