1988 K5 Blazer. TBI/700r4 to LS 5.3/4L60E. Need some advice

[Austin4wd]

Ok guys, I have an '88 K5, so it is still a square body. It's got the factory TBI system on it, but I'm wanting to upgrade. I want to replace the 350/700r4 with a 5.3/4L60E but I want to keep the NP208. I've done an 6L in '71 3/4 ton, but not in a TBI truck so I have a few questions.
1: Will my current fuel pump work and if not, is there one that will work?
2: What engine mounts will I need on my frame and engine?
3: What 4L60E will bolt to my 208?
4: My truck has no lift kit, so will it be in the same position as the 700r4?
5: I have a cable-driven speedometer, will I need to upgrade to an electronic one, or can I mix the 4L60E with the 700r4 parts to make it a cable driven one? Trying to save money on it.
6: What exhaust manifolds will I need, or do I need to make them? I want them to bolt into my factory collectors so I can keep my current exhaust system
Any reviews are helpful! I plan on getting the bits and pieces ready for when my 350 dies

[fitz]

Your speedo cable is driven off the 208.  In sure others can help out with the other questions.

[Irish_Alley]

Ok guys, I have an '88 K5, so it is still a square body. It's got the factory TBI system on it, but I'm wanting to upgrade. I want to replace the 350/700r4 with a 5.3/4L60E but I want to keep the NP208. I've done an 6L in '71 3/4 ton, but not in a TBI truck so I have a few questions.
1: Will my current fuel pump work and if not, is there one that will work?
no your stock pump will only do 15 psi max you need 60 psi
http://www.rockauto.com/en/parts/acdelco,EP381,fuel+pump,6256 will get you there
2: What engine mounts will I need on my frame and engine?
3: What 4L60E will bolt to my 208?
its not what 4l60e, all 4l60e/700r4 will have 27 splines. so the t case can swap right over. but the spline length might be a problem (i.e. a 4x4 shaft is shorter than a 4x2)

4: My truck has no lift kit, so will it be in the same position as the 700r4?
yes
5: I have a cable-driven speedometer, will I need to upgrade to an electronic one, or can I mix the 4L60E with the 700r4 parts to make it a cable driven one? Trying to save money on it.
yes youre speedo cable will be on the t case but you need an electic signal for the ecm to know your speed and shift points
6: What exhaust manifolds will I need, or do I need to make them? I want them to bolt into my factory collectors so I can keep my current exhaust system
dont know if anything will be a direct bolt on
Any reviews are helpful! I plan on getting the bits and pieces ready for when my 350 dies

[Austin4wd]

Thanks guys for replies. Sorry I was away went out part shopping and found I need a 4wd 4l60 from 93-96 to pull this off. I'm thinking maybe ordering a pump from a 5.3 truck and mounting it in my tank so it all works like '05 and such. Irish_Alley, what electronic signal would I need to make the shift points happen? I heard 2010 Camaro SS headers would work but is it possible to take a pair of 5.3 headers and weld in the bottom so they're the bottom half of a SBC shorty header? Cause if it would work I'll do it that way. Any more help on my other questions is appreciated guys! 

[Irish_Alley]

you need the following signals for the basic tcu to work. TPS, rpm and output shaft speed sensor. theres more sensors but you might be able to get away with not using them depending on the tcu. i also have a "black box" for my 4l80e its pretty simple and you just plug it in then give it 12v and a couple grounds. but it makes the automatic trans a manual shift but its reversible

[Displaced_Txn]

or you could easily swap to a np241c with passenger drop and have an electronic vss signal, what i did when i went with a 4l70e, thats if you want to have the engine shift the trans correctly and also uses it for other things i believe.

your engine mounts you can pick and choose, dirty dingo, holley, Diy4x etc i went with the diy4x as it gets rid of the factory clamshell and uses 1/2 poly spring bushings

[Austin4wd]

or you could easily swap to a np241c with passenger drop and have an electronic vss signal, what i did when i went with a 4l70e, thats if you want to have the engine shift the trans correctly and also uses it for other things i believe.

your engine mounts you can pick and choose, dirty dingo, holley, Diy4x etc i went with the diy4x as it gets rid of the factory clamshell and uses 1/2 poly spring bushings

Displaced_Txn, I could, my buddy has a '90 K5 with the 241 passenger side drop, but then I need his front driveshaft as well. Unfortunately, GM is a bit picky there. Did the DIY4x ones put it in the right spot with the proper angles?

Irish_Alley, would putting in an 241 t-case solve my problem? and I plan on adding a tachometer into this beast as TBI squares never came with one factory, which blows. I plan on pretty much making this thing run identical to a 2005 Chevy 1500 but still be able to wax a brand new Raptor off-road in a 27 year old truck

[roundhouse]

CK5.com and pirate4x4.com have lots of info on the swaps

I just finished installing a 5.3 in a 77 K-10 pickup
We used the dingo motor mounts and had to move the Trans 1.5 inches forward

We already had TBI on this truck so we swapped the in tank pump for one from a 96-99 pickup

Adding a tach is easy.   The LS computer has a wide for that and vendors sell a tach that fits where the fuel gauge is and includes a fuel gauge

I think you can use the Trans that will come with the LS

We used "team208motorsports" to tune the computer
I did the harness work using lt1swap.com as a guide.   But if I had it to do over I'd just leave the harness stock
It will work fine like just like it comes and saves 11 hours of work

We used 2013 camaro manifolds
You're not going to find something that will bolt directly up to your existing pipes.   The downpipes/cats came with the manifolds and cut off the back cats knocked out the inside of the front cats and slightly twisted the pipes and welded them back on and it almost perfectly met up with the collector flanges  where the headers used to be

Be selective about where you get the engine
If you have room get the entire donor vehicle and remove the engine yourself
There are lots of items that the salvage yard will damage
They will cut fuel lines that you can use
they will cut wires that you need
They will let the engine fall over and smash the coil packs and crack the valve covers and oil pan and the fan
They will mix up parts like the MAF meter from other cars

They will cut the throttle cable instead of spending the three minutes to remove it from the vehicle

They will tell you the donor vehicle had 120K miles on it and then when you run a car fax on the VIN it shows 18 owners and 267K miles

Basically anything and everything the salvage yard says will be a lie
Do NOT buy an engine if you can't hear it run still in the wrecked car
Save all this trouble and get the entire donor vehicle

Sent from my iPhone using Tapatalk

[Austin4wd]

CK5.com and pirate4x4.com have lots of info on the swaps

I just finished installing a 5.3 in a 77 K-10 pickup
We used the dingo motor mounts and had to move the Trans 1.5 inches forward.
I don't want to move the trans forward any, as I want to keep the factory driveshafts still. Again, this is a daily driver, not a three year build. When the K5 is down getting swapped, I'll be driving my K20 as a daily


We already had TBI on this truck so we swapped the in tank pump for one from a 96-99 pickup

Adding a tach is easy.   The LS computer has a wide for that and vendors sell a tach that fits where the fuel gauge is and includes a fuel gauge

I think you can use the Trans that will come with the LS 
Unfortunately, the trans from the LS wont bolt to my transfer case, and as I don't want to get a custom front diff made, I find it easier to use the passenger-side drop 241 with electric speedometer behind a 93-96 4L60E, and I've looked at my buddies truck, he does have it and doesn't need it.


We used "team208motorsports" to tune the computer
I did the harness work using lt1swap.com as a guide.   But if I had it to do over I'd just leave the harness stock
It will work fine like just like it comes and saves 11 hours of work
I kinda plan on building my own gauge cluster, using mostly an old one with a tach, and adding the electric speedo. Hopefully, all of this will trick the 5.3/4L60 into running the settings like it was a 2003 GMC or Chevy or whatever parts truck I get.

We used 2013 camaro manifolds
You're not going to find something that will bolt directly up to your existing pipes.   The downpipes/cats came with the manifolds and cut off the back cats knocked out the inside of the front cats and slightly twisted the pipes and welded them back on and it almost perfectly met up with the collector flanges  where the headers used to be
THANK YOU!! I needed so much help on that! I plan on cutting the top of my pipes and rewelding them when I get a fit, and applying the LS collectors on it

Be selective about where you get the engine
If you have room get the entire donor vehicle and remove the engine yourself
There are lots of items that the salvage yard will damage
They will cut fuel lines that you can use
they will cut wires that you need
They will let the engine fall over and smash the coil packs and crack the valve covers and oil pan and the fan
They will mix up parts like the MAF meter from other cars

They will cut the throttle cable instead of spending the three minutes to remove it from the vehicle

They will tell you the donor vehicle had 120K miles on it and then when you run a car fax on the VIN it shows 18 owners and 267K miles

Basically anything and everything the salvage yard says will be a lie
Do NOT buy an engine if you can't hear it run still in the wrecked car
Save all this trouble and get the entire donor vehicle
I plan on taking the whole truck, so I have as much wiring and parts as I can get.

[/color][/color]Sent from my iPhone using Tapatalk

[Austin4wd]

Bumping the post. Found a couple other bits and pieces for the swap and I now have the transfer case, gauge cluster and all the speedometer parts