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V6 to V8 engine swap

This is a discussion on V6 to V8 engine swap within the Technical / Maintenance forums, part of the General Discussion category; Other than the engine and transmission what else would I have to change/do to swap my engine out with a ...

  1. #1
    Tiger Tiger's Avatar
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    V6 to V8 engine swap


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    Other than the engine and transmission what else would I have to change/do to swap my engine out with a V8?
    Is any one V8 engine thats easier to swap out?
    Last edited by Tiger; 01-12-2009 at 06:13 PM.
    1994 4.3 V6 reg. cab, short bed.

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    Re: V6 to V8 engine swap

    potentially drive shaft if the trans is diff length.

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    Registered User ABK1500's Avatar
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    Re: V6 to V8 engine swap

    I'm assuming the truck in your sig?

    Anyway, find a TBI 350, it will bolt up to your current tranny, and get the associated wiring with the 350.

    You may or may not need new motor mounts, I don't remember.

    98 ECSB/265s/Swapped 350/NV3500 /Airaid/Flowmaster/3.73/Alpine/Kicker

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    Re: V6 to V8 engine swap

    Wouldn't the wiring be the same from the 4.3 to the 350? It's only 2 injectors for each engine, or is some too short due to the shorter block?
    Quote Originally Posted by Quyonmob View Post
    Straight pipes are for peckerheads. . .
    '98 K1500 ECSB 5.7, 4L80E, 14BSF, 4.10/G80, 7,200# GVW springs, 8600# GVW calipers/pads, EFI Live, TB mod, UDs, block, crank, 285s, and a lot of stuff on the shelf.

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    Re: V6 to V8 engine swap

    The injectors are the same. I didn't think that I was going to be able to use the same wiring harness and tranny though. That's awsome.
    My sig is the truck that I just got. the reason I want to do the swap is because I got the truck with two cracked heads and I figured I could probably get a used V8 for the price of 2 new heads. I think the V6 hurts my pride a little as well.
    1994 4.3 V6 reg. cab, short bed.

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    Tiger Tiger's Avatar
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    Re: V6 to V8 engine swap

    The motor mounts are a little different though. They are like a step back. I would go outside and take a picture but my girlfriend is out doing something with the camera.
    Last edited by Tiger; 01-12-2009 at 07:40 PM.
    1994 4.3 V6 reg. cab, short bed.

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    Re: V6 to V8 engine swap

    The motor mounts are a little different though. They are like a step back. I would go outside and take a picture but my girlfriend is out doing something with the camera.
    1994 4.3 V6 reg. cab, short bed.

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    Registered User ABK1500's Avatar
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    Re: V6 to V8 engine swap

    If they were like mine (although my truck is a Vortec), they v6 motor mounts will not work, they are to far back.
    V8 mounts are not hard to come by though...

    98 ECSB/265s/Swapped 350/NV3500 /Airaid/Flowmaster/3.73/Alpine/Kicker

    Carpe deim. Seize the carp.

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    Supporting Gold Member GreaseDog's Avatar
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    Re: V6 to V8 engine swap

    the motor mounts themselves are the same, they're just positioned too far back. move them forward on the frame (the holes should already be there), and you should be fine. you may have to lengthen a couple wires, but that's about it. swap your TB for a comparable year TB for a 350 (larger bore IIRC and larger injectors) get a custom tune for your year truck with a 350, and call it good.
    77 Chevy K20 - 80 GMC K2500 (in pieces)
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    Re: V6 to V8 engine swap

    Remove the V6 brackets on the frame and bolt in new motor mounts using the existing holes. You'll need to lengthen the wires on the temp sensor on the driver's side head and the wire on the passenger's side knock sensor. There could be a few more but I haven't found them yet. If you can find a complete TBI 350 that would be your best bet. Be sure and keep the metal brackets on the bottom side of the engine as you will need them to bolt it to the new motor mounts. If you are keeping your original trans, you wont have any problems with driveshaft length. It will all stay in the original location. You can reuse the original wiring harness. You can even take the injectors from the 350 and put them in your original TB unit if it's in better shape. I just got my 350 swapped in about a week ago and am doing the wiring now.
    Last edited by SuperChevy17; 01-13-2009 at 07:03 AM.
    95 Chevy 2wd TBI Vortec 350 5spd. *Ultimate Budget Engine Swap*
    Engine: 98 4-bolt Vortec 350|Scat Crank|LT4 Production Cam|1.6 Proform Full Roller Rockers|Edelbrock EPS Intake|454 Throttle Body|Hedman Elite 69840 LT|ZOOM Perfection Clutch|Custom Tune by TBIChips

    98 ecsb 4x4 38" TSLs

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    Re: V6 to V8 engine swap

    You can use the wiring harness, you need a 350 computer.
    You need new mounts, and ESC (Electronic Spark Contorl Module) for a 350.
    The trans should work fine, but it may not last behind a 350.
    That's about it.


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    Supporting Gold Member GreaseDog's Avatar
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    Re: V6 to V8 engine swap

    ah, and the distributor.
    77 Chevy K20 - 80 GMC K2500 (in pieces)
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    Smokin 38s SuperChevy17's Avatar
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    Re: V6 to V8 engine swap

    Yep, forgot to mention the computer. Or you can send the V6 chip off to have it custom tuned.

    I assumed the distributor would come with the motor. But if not, then you will need the V8 dist. A complete TBI 350 engine will be easiest to swap in. You didn't mention what trans it was, but if it's manual, then you'll need clutch, pressure plate, & flywheel for V8 also.
    95 Chevy 2wd TBI Vortec 350 5spd. *Ultimate Budget Engine Swap*
    Engine: 98 4-bolt Vortec 350|Scat Crank|LT4 Production Cam|1.6 Proform Full Roller Rockers|Edelbrock EPS Intake|454 Throttle Body|Hedman Elite 69840 LT|ZOOM Perfection Clutch|Custom Tune by TBIChips

    98 ecsb 4x4 38" TSLs

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    Supporting Gold Member GreaseDog's Avatar
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    Re: V6 to V8 engine swap

    the 4.3 flywheel and clutch should fit the 5.7 just fine.
    77 Chevy K20 - 80 GMC K2500 (in pieces)
    90 Chevy K3500 - 93 Chevy C2500 (in pieces) - 94 Chevy K1500

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    Registered User ABK1500's Avatar
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    Re: V6 to V8 engine swap

    Quote Originally Posted by GreaseDog
    the 4.3 flywheel and clutch should fit the 5.7 just fine.
    Transferred over on mine w/o a problem. I did however need new motor mounts.

    98 ECSB/265s/Swapped 350/NV3500 /Airaid/Flowmaster/3.73/Alpine/Kicker

    Carpe deim. Seize the carp.

  16. #16
    Smokin 38s SuperChevy17's Avatar
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    Re: V6 to V8 engine swap

    Do you really think you should use the smaller V6 clutch behind a V8?
    95 Chevy 2wd TBI Vortec 350 5spd. *Ultimate Budget Engine Swap*
    Engine: 98 4-bolt Vortec 350|Scat Crank|LT4 Production Cam|1.6 Proform Full Roller Rockers|Edelbrock EPS Intake|454 Throttle Body|Hedman Elite 69840 LT|ZOOM Perfection Clutch|Custom Tune by TBIChips

    98 ecsb 4x4 38" TSLs

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    Supporting Gold Member GreaseDog's Avatar
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    Re: V6 to V8 engine swap

    if it is in fact smaller, its not going to be THAT much smaller that it wont work. if its worn, replace it and upgrade.
    77 Chevy K20 - 80 GMC K2500 (in pieces)
    90 Chevy K3500 - 93 Chevy C2500 (in pieces) - 94 Chevy K1500

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    Re: V6 to V8 engine swap

    If you went backwards say to put a v6 into a truck that had a v8 would I need to replace the tranny and rear?

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    Re: V6 to V8 engine swap

    V-6 radiator usable on the V-8?

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    Registered User Doober's Avatar
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    Re: V6 to V8 engine swap

    The transmission & rear can stay in place.

    It could be hooked up, whether it will cool sufficiently I don't know. I'm looking for motor mount info myself, and also about the fuel lines, is there any issue with those going from a 4.3 to SBC? Far as the motor mounts, it's just moving them to the proper location on the frame?

    '92 Sierra (TBI 383/Vortecs/Comp 08-412-8/EBL/4L60/3.08s), '78 Malibu (Vortec'd 350/4-speed/2.29s), '87 Pontiac Fiero GT (2.8 v6/5-speed)


 

 
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