Author Topic: 86 C20 4.8/5.3 swap  (Read 5188 times)

Offline mizozuman2

  • Newbie
  • Posts: 72
  • Something goes here... but what?
86 C20 4.8/5.3 swap
« on: September 25, 2014, 05:48:22 PM »
Hi all,

I've got an '86 C20 I'm thinking about doing a 4.8/5.3 swap in. I would do a 6.0, but they're just a bit too far out of budget.

Anyways, I'm curious as to what all I need to make this swap happen.

I'm getting a 4.8/5.3 from a salvage yard. It comes with the complete engine, trans, wiring harness and computers, along with the serpentine assembly.

I'm not too worried about the mechanical gauges working ATM, as I plan on swapping it out to some Digital gauges (Not the Dakota Digital). But, Power steering and A/C are a MUST.

Right now, I need to know what all parts I MUST have to do the swap.

All I can think of right now is:
-Trans Cross member
-Engine Mounts
-Oil Pan
-Drive By Cable setup (Not wire)
-wiring harness for engine

Now, for a few questions.

Painless Performance has a wiring harness for the C20, what is it for? If I have the engine wiring harness, do I need the one from Painless?
Do I need to get a different driveshaft? Same length? Does it need cut?

If I am missing anything, or if there's any tips. please let me know!

1986 Chevrolet C10 "Heavy Half"
350 4bbl
Long bed/Reg Cab

Offline mizozuman2

  • Newbie
  • Posts: 72
  • Something goes here... but what?
Re: 86 C20 4.8/5.3 swap
« Reply #1 on: September 29, 2014, 11:30:08 AM »
More questions

1. Is there a difference in Fuel Sending Units from the 16 gallon and the 20 gallon tanks? there's a few on Summit, but doesn't specify on the tank size.

2. I'm planning on putting new tanks in. since I'm going from Carb to EFI, do I need a baffled tank? the 87's have a baffled tank if I remember correctly. where the 86 doesn't.

3. Does anyone sell an Adapter plate to run the stock A/C compressor from the truck on the LS engine? if not, what would be needed to run the LS Compressor on the truck?

4. Other than VATS, is there anything else that needs deleted in the computer? I do plan on running an o2 Sensor.

5. will long tubes cause problems with the Transmission Crossmember? I have headers on the 350 in my truck now, and there's about 20-24 inches between the collector and the crossmember. I have a piece of flexpipe to make it over/under the crossmember on each side.

6. Will I need to make my own grommet hole to the cab to put the Computer's behind the dash? or is the stock grommet on the drivers side enough?

7. will the driveshaft need cut? I have a 350 and a TH350, and going to a 5.3/4l60e from a truck.

8. the stock LS truck pan will fit, correct? or do I need an f-body pan? i plan on a 2/4 drop in the future as well.
1986 Chevrolet C10 "Heavy Half"
350 4bbl
Long bed/Reg Cab

Offline Captkaos

  • OWNER and Administrator
  • Administrator
  • Senior Member
  • *****
  • Posts: 18126
Re: 86 C20 4.8/5.3 swap
« Reply #2 on: October 09, 2014, 09:03:10 PM »
You already have a harness if it is coming with the motor.  If you want drive by wire, get the motor with it along with the harness and TAC.
You just need to move the crossmember back, no need to purchase a new one.
Stock oil pan will work.  I am running the stock one on mine and it is drop 2.5/4"
Headers for a C20, El Camino long tubes work, or Hedman husler 3/4 lenght or if you are running a 4L80E, Street and performance
The factory radiator can be made to work also.  I modified the heater return for the steam hole on mine.

The painless harness is the complete truck harness, if it is running driving now and nothing is hacked you don't need it.
As for the driveshaft, it depends on what is in the truck now and what transmission you are getting.  If it has a 700R4 and you are using a 4L60E it is the same trans, so if you mount the engine in the same spot the driveshaft should work.

You need to think about fuel lines (eliminating all rubber) and fuel fittings for the LS rail and the Sending unit.
You also need to keep in mind how you are going to get signal to the Speedo (as in the speedo needs to be able to read the signal.

Sending unit will be the same.  I recommend getting the 1987 version and mount a EP381 pump to it.

If you are buying tanks get the baffled ones. 1987-1991

For the AC, I recommend this, it is what I am using and will be using on my other truck:

Running the O2 is required, VATS will have to be deleted to get it running, I would delete the rear O2's nothing else needs to be deleted.

Shouldn't cause an issue.  Several use them

You can run the computer under the hood.  It simplifies a lot of wiring.  It is work putting it under the dash, I did it...

The dirveshaft will need to shortened and rebalanced if going from a TH350.

Again, stock pan will work fine.