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LS swap checklist

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possum70

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Ok. I have a 1978 Blazer and the 350 is no longer any good. I will be putting in a new engine and have decided to upgrade to fuel injection. I have been reading all sorts of stuff here and found some good stuff but some people already have some fuel injection or are keeping this or that and getting rid of other things.
May I give a list of my desires for this and ask if I need anything else. Our Pick and Pull is having half price weekend this weekend and it would be nice to get thie necessities for half off.
I know I want the fuel injection and therefore need a computer with the motor. I will be putting in the Windstar fans. I will also be getting the wiring harness. I'm thinking a 5.3 right now, btw. I'm not sure about the electric fuel pump in the tank or not. Will I be losing power or fuel economy if I have an exterior pump? How about the power steering pump? I'm guessing a 1978 version may not work? Maybe?
I know exhaust and all that will have to be "adjusted" but I just need to know what I should pick up this weekend.

Any and all help is greatly appreciated.

possum
 
I see your local there! You will need new exhaust more then likely, you need to use the LS/5.3 power steering pump,grab transmission also as you will need it and grab entire harness and computer.
 
Run an in tank pump, you'll be much happier. The externals have a terrible tendency to be insanely loud. All you need is a tank unit from a TBI truck, a vortec or aftermarket pump and some wiring which would have to be done with an external anyway.

Exhaust, if you really want to keep your existing to save some money, should only require new down/y pipe.

You wont regret going to an LS. TBI isnt a bad swap if you are satisfied with a stock engine but the second you desire more power/ to modify the motor TBI will give you headaches and an LS is a much better option.
 
My budget is variable. I'll be spending money as I get enough for whatever is necessary. Needless to say "as little as possible". What transmission should I look for that could hook up to a NP203? Or should I think about all of them? I'd like to get by with what I have and upgrade later, if possible.
For a blazer TBI tank, what will have that kind of tank?

Possum
 
At half price I'd remove everything attached to the motor, and make sure they consider that part of it. Wiring, *everything*. I'd expect you'd need to cut nothing, as it should all come with it. Maybe some unplugging/unbolting, but take everything that is connected.

On the tank/pump unit, if you need to save money (with this sort of swap, I wouldn't skimp, but that's me) might be worth it if you can find a '87+ K5 or Suburban, and pull the sending unit from it. I personally don't think running a used tank at this point is worth it, but if you could find a good one, take the sending unit out, make sure the baffle isn't broken, and it wasn't full or rust, use it. Can buy a new tank for ~$100, new sending unit probably another $100+, so potentially some money to be saved, but both the sending units and tanks are iffy to buy used, so need inspected before dropping any money on them, no matter how cheap.
 
The accessories ie, alternator, ps pump, a/c etc are not included. But a gen 3 motor is normally only $400 so this weekend they will be $200. Computer is @$50. Should be good if I can find what I need. I think I will do an in tank pump.

Possum
 
If the donor you find is drive by wire make sure to get the gas pedal assembly from the same truck the motor came from...
 
I have a TH350/NP203 right now. Does a 350 bolt to the 5.3? Or will I need to get the tranny (4L60e or whatever) and will that bolt up to the t-case? Or am I gonna need to pull all of it off the donor truck? I'm not against all that but eventually I'd like a doubler (of course, who wouldn't) and the 203 would be nice to keep. Also, do 5.3s have the same bolt pattern on the back?

possum
 
Old school trans will bolt up it just won't utilize the very top bolt hole in the block.

Depending on trans setup and engine you will need a flex plate spacer to adapt the converter.
 
With work I drive by the Raleigh/Clayton site on Mondays, the Durham site on Thursday and at home I'm actually closer to the Greensboro site than Durham by a few miles. Never been to the Greensboro one though. It's not on my route. I need to stop by each one and see if I can find something useful for Saturday morning.

possum
 
Personally I'd strongly advise using the 4L60E, although I can't speak to any issues with a doubler later. You'd have to program the auto trans out of the PCM to get the setup to work right, and you'd be losing OD. I guess if offroad only who cares, but if any freeway trips, OD is nice, especially if you want to run good gears in it.
 
You can look through my build thread to see what you'll need and what issues you may run into since I just finished the swap myself.

I can't speak for the pick 'n pull where you are, but around here they pre-pull any engine that new and sell it elswhere so I'm not sure you'll be able to get an LS at their 1/2 price sale.

If it were me, I'd want to get an engine "fully dressed". Engine, wiring harness, all the attached accessories and computer off of the same truck.

As was mentioned before, you don't need the transmission, it will bolt up to what you have now but you will need a new flywheel/flex plate. If you can afford it though, it's a good upgrade. I wish I would have swapped the tranny in mine.

When you pull it, get the power steering lines as well. The lines have metric fittings. I'm not sure if your steering box will have the right style fittings but if not it's cheap and easy to get a later model box that does.

Don't be scared of using an external pump but if you can, get a later model blazer tank with an internal pump. It is about the same cost anyway, so why not. Get as much of the fuel line as you can too. The AN fittings are expensive so using stock fuel fittings as much as you can will save cash.

I also used windstar fans and it's worked out great.

Get as much of the wiring harness as you can. If I'd have had the option I would have gotten everything up to every connector that went to the truck, and then also cut off the other end of the connector (and enough wire to solder to) and taken that as well. It would have made some things a little easier.

If it's there, take the y-pipe. It'll go out the passenger side which probably won't work for you but you can modify it and save a lot of cash. Again, details in my thread. Don't forget to get the front O2 sensors even if you can't get the rest of the y-pipe.

That's everything I can think of off the top of my head. GL
 
Get an engine, harness, and computer from the same vehicle, and if it is a 2003 and later, don't forget the throttle pedal.

You will need adapter plates for the motor mounts
Engine crossmember will need to be replaced or modified.
Notched frame for exhaust manifolds, unless you use F body Camaro manifolds or aftermarket headers.
You will need your wiring harness to be modified. I chose to buy a brand new harness and not even mess with a factory harness, but that costs more.
You will need to have the computer reprogrammed.
Your steering box will have to be replaced by an 1981 box or newer, it's simply the same box with a different style fitting that is still used today and the LS power steering pump lines will bolt in to the 80's steering box.

I use an external Walbro fuel pump, personally I don't see the fuss over it. It's not that loud and is inaudible from the cab with the engine running. I have zero plans to swap in a later tank and intank pump.

Bottom line, there are tons of small things with an LS swap, it is not a bolt in and go in one day kind of swap. But, it's not that hard on the flip side, just time consuming.
 
Will the new trannies all bolt up to the 5.3? like the 4l60, 4l80, or 6l80? Also, will I be able to put the NP203 onto these trannies or will I need a new transfer case? I would like to keep mine but mainly because I know it. The new stuff boggles me.:dunno:

possum
 
6l80 requires its on control module. Last I read it was a handful to swap it in but this was years ago.
 
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