Author Topic: Lsx swap in 1985 swb c10  (Read 347 times)

Offline kylen52

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Lsx swap in 1985 swb c10
« on: July 17, 2017, 03:27:56 PM »
New to the forum, wanting to put a 99 5.3 out of a gmc in my 1985 Chevy c10, would like to know yall's opinion on the parts I'll need, I've got a pretty good idea of the parts I'll need I just wanna make sure I'm not missing anything

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Offline kylen52

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Re: Lsx swap in 1985 swb c10
« Reply #1 on: July 19, 2017, 10:05:49 AM »
Guess no one is gonna help me out

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Online ehjorten

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Re: Lsx swap in 1985 swb c10
« Reply #2 on: July 19, 2017, 01:59:00 PM »
donor engine
donor harness
conversion mounts
replace all rubber fuel lines with F.I. rated hose and hose clamps
custom flex lines to run from hard line in frame to engine
high pressure electric fuel pump
A 5/16" return line to the tank if you don't already have one.
MAF Sensor and intake duct work
Some sort of exhaust work...headers...downpipes, etc. with bungs and O2 sensors
Stand alone DIY electrical harness with fuses and relays to power it...or buy a custom harness
PCM and reprogramming for your vehicle
Some sort of radiator work to either install a steam line port or use the JTR adapter to plumb the steamline
Maybe an A/C relocation kit if you have A/C and intend to retain it.
Accelerator pedal cable to go between your pedal an the throttle body
Some supplies to plumb your power steering, etc.
And maybe the Vacuum booster quick connect fitting at the back of the manifold if you don't already have that.  Some come with a plug for vehicles that had hydroboost.
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline kylen52

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Re: Lsx swap in 1985 swb c10
« Reply #3 on: July 19, 2017, 02:07:22 PM »
I've already got the motor and transmission, plan on putting a stage 4 cam low lift in it, and maybe eventually supercharging it

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Online ehjorten

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Re: Lsx swap in 1985 swb c10
« Reply #4 on: July 19, 2017, 02:14:31 PM »
Dual tanks?  You might want to get new '87+ tanks and go with the in-tank pumps.  You can retain the switching valve, but you have to be sure it is the upgraded one that can handle 65 psi fuel pressure.  Pollak was the manufacturer that made the switching valves.  They still make the 42-154 6-port switching valve.
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline kylen52

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Re: Lsx swap in 1985 swb c10
« Reply #5 on: July 20, 2017, 10:21:50 AM »
What about a drive shaft? Or will I have to get one made

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Online ehjorten

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Re: Lsx swap in 1985 swb c10
« Reply #6 on: July 20, 2017, 01:44:51 PM »
Totally depends on what you are starting with and what you are going to for a drivetrain.  You can keep the back of the LS engine block in the same position as the stock engine.  Then it comes down to the length of the transmission.  If the transmission you are going to is longer, then you can have your current driveshaft shortened.  Depending on what yokes you have you might need to change those out, or get a conversion U-joint.  If the transmission is shorter, then you can't lengthen a driveshaft per say...you will have to have it re-tubed.  That is a little more expensive as they totally replace the entire length of the driveshaft tube with a longer one.
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline kylen52

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Re: Lsx swap in 1985 swb c10
« Reply #7 on: July 20, 2017, 02:14:20 PM »
My grandpa owns a salvage yard, I'm sure I can come up with some yokes

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Offline roundhouse

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Lsx swap in 1985 swb c10
« Reply #8 on: July 22, 2017, 11:11:53 AM »
We used
http://www.team208motorsports.com

To do the tuning
We did the harness mods ourselves but for the next one we are gonna have team208 do it
I highly recommend him
He does a lot of tuning of race trucks , in real time with a cellphone telemetry setup

After each short course he will download the data and retune the software for that specific course , tires, gear ratio, etc

He mods it and adds a fusebox with three or four wires to hook up and you're running

There's a lot of articles on the web about what parts you need

It varies a lot depending on the donor and if you have drive by wire  or cable etc

We used late model camaro exhaust manifolds

We flipped the injector rail to put the hose connections on the front passenger side
Takes an hour with a sawzall and dremel to removes some tabs from the intake but it worth it if you want to have your fuel lines on the passenger side

Get an 87 tank from rockauto.com

Modify the late mode pump to fit inside .


There is no one article that's going to cover everything you need to do
Just too many variables

Use using a slushbox or a manual transmission ?

We used a NV-3500 from a 07 Silverado and love it !

I have a NV3550 in my 74 Bronco and it's a blast

If you want to use an auto then pull the engine and Trans from the same donor vehicle
Don't try to mix and match
From different cars

We used a stock 2002 5.3 with 270k on it with no mods
Just changed the intake , valve cover and oil pan gaskets

Once your Tuner deletes the torque management (GM can't make an auto Trans that will last behind a V-8)
And deletes the emission software
You would be surprised at the power of a stock high Milage LS

Ours has easily double the power of the 4 bbl 350 it replaced


The rear exhaust manifold bolts WILL snap off when you try to remove them
  GM used glue on them for some reason

Heating them with a torch before you try to remove them may help but probably not
So be prepared to drill them out and clean up the threads with a tap


Everyone worries about the driveshaft

That's the easiest mod
Before you remove the old one Measure carefully from center of the U joint caps on each end

When then Trans is in measure from the same place
Take your old shaft and $100 to a driveshaft shop and have them shorten and rebalance it

You will spend more money and lot and lots more time on the fuel lines and fittings and filters  and tank

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« Last Edit: July 22, 2017, 11:27:18 AM by roundhouse »

Offline kylen52

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Re: Lsx swap in 1985 swb c10
« Reply #9 on: July 22, 2017, 11:33:27 AM »
I've heard the fuel lines take the longest, watched a guy on YouTube and I liked his idea, probably go with his set up, the motor im going to use is out of a 99 gmc, and the trans is out of a 99 chevy, which is a cable not drive by wire


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