454 or 350 TBI swap into 4x4?? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

bfr57 · 01-02-2008, 05:29 PM

Got a 71 Chevy 4x4 with tired 350. I have available a good 454 or 88 350 TBI motor. The TBI would just be wiring, if it's that simple? The big block is another question. How much does it take to get it to fit into the 4x4 configuration? This has rear dump exhaust manifolds; will they work? Does firewall have to be dimpled? Will it fit into 350 motor mounts. Anything else I should consider?

1969k10stepside · 01-02-2008, 05:32 PM

Generally when using a big block in a 4wd there is clearance issues with the valve covers and the distributor hitting the firewall.Modifying the firewall,using a body lift or locate the motor/tranny/t-case farther forward and lengthening/shortening the driveshafts can solve those issues..

bfr57 · 01-02-2008, 06:14 PM

I've already moved driveline previously for a 700R4 swap. I would rather not go that route. How much of a body lift is needed?

1969k10stepside · 01-02-2008, 06:28 PM

If you used a 700R4 and you moved the motor forward it should be forward enough to avoid the clearance issues with the firewall.The 700R4's extra length should allow the motor to be moved to a better spot but use the stock driveshafts and keep the transfer case in the stock spot.Or did you move them back already when installing the 700R4 and leave the motor in the stock spot?As for the body lift,each truck is different.Some don't even need to modify or dent in the firewall for it to fit while others need a 3" or 4" body lift..You won't know till you put it in there.

extd56 · 01-02-2008, 06:49 PM

I am putting a 454 in my 69 crew cab. It fit fine when I used the 350 mounts but I moved it forward a little bit so that I could use the front drive shaft. I had to modify the rear shaft anyways because I am going to a 4L80E with a 241 from a 350 with a 205 transfer case.

ND_guy · 01-03-2008, 05:38 PM

The tbi swap isn't to bad if you do alot of studying and can read a pinout schematic. I just fired my sbc tbi conversion for the first time today and it fired the first time(I usually dont get that lucky). I probobly have 40 hours in wiring, 10 hours in fuel system, 10 hours in the swap itself. The projec would have been much faster with a premade harness from painless or someone else but I am too cheap to give them 400 dollars.
just my 2 cents.

01-02-2008, 05:29 PM	#1
bfr57 Registered User Join Date: Jul 2003 Location: Tucson, AZ Posts: 111	454 or 350 TBI swap into 4x4?? Got a 71 Chevy 4x4 with tired 350. I have available a good 454 or 88 350 TBI motor. The TBI would just be wiring, if it's that simple? The big block is another question. How much does it take to get it to fit into the 4x4 configuration? This has rear dump exhaust manifolds; will they work? Does firewall have to be dimpled? Will it fit into 350 motor mounts. Anything else I should consider?

01-02-2008, 05:32 PM	#2
1969k10stepside Registered User Join Date: Mar 2006 Location: USA Posts: 21,019	Re: 454 or 350 TBI swap into 4x4?? Generally when using a big block in a 4wd there is clearance issues with the valve covers and the distributor hitting the firewall.Modifying the firewall,using a body lift or locate the motor/tranny/t-case farther forward and lengthening/shortening the driveshafts can solve those issues.. Last edited by 1969k10stepside; 01-02-2008 at 05:33 PM.

01-02-2008, 06:14 PM	#3
bfr57 Registered User Join Date: Jul 2003 Location: Tucson, AZ Posts: 111	Re: 454 or 350 TBI swap into 4x4?? I've already moved driveline previously for a 700R4 swap. I would rather not go that route. How much of a body lift is needed?

01-02-2008, 06:28 PM	#4
1969k10stepside Registered User Join Date: Mar 2006 Location: USA Posts: 21,019	Re: 454 or 350 TBI swap into 4x4?? If you used a 700R4 and you moved the motor forward it should be forward enough to avoid the clearance issues with the firewall.The 700R4's extra length should allow the motor to be moved to a better spot but use the stock driveshafts and keep the transfer case in the stock spot.Or did you move them back already when installing the 700R4 and leave the motor in the stock spot?As for the body lift,each truck is different.Some don't even need to modify or dent in the firewall for it to fit while others need a 3" or 4" body lift..You won't know till you put it in there. Last edited by 1969k10stepside; 01-02-2008 at 06:31 PM.

01-02-2008, 06:49 PM	#5
extd56 Senior Member Join Date: Nov 2004 Location: Vacaville, CA Posts: 2,272	Re: 454 or 350 TBI swap into 4x4?? I am putting a 454 in my 69 crew cab. It fit fine when I used the 350 mounts but I moved it forward a little bit so that I could use the front drive shaft. I had to modify the rear shaft anyways because I am going to a 4L80E with a 241 from a 350 with a 205 transfer case. Attached Images

01-03-2008, 05:38 PM	#6
ND_guy Tool Addiction=Money Shortage Join Date: Mar 2006 Location: Grand Forks, ND Posts: 233	Re: 454 or 350 TBI swap into 4x4?? The tbi swap isn't to bad if you do alot of studying and can read a pinout schematic. I just fired my sbc tbi conversion for the first time today and it fired the first time(I usually dont get that lucky). I probobly have 40 hours in wiring, 10 hours in fuel system, 10 hours in the swap itself. The projec would have been much faster with a premade harness from painless or someone else but I am too cheap to give them 400 dollars. just my 2 cents. __________________ 1967 K20 400TBI SM465/NP205 posi front, Detroit locker 4.56 rear



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