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75 K-5 5.3 LS transplant [with pics]

buefchris said:
As of right now, the HP is 239[at the wheel] and 269 ft lbs of torque. LS baby! no matter what c.i.d, it's the best swap going.
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239 at the wheels is respectable. (for a stock engine) I'm sure there are crazy losses with these drivetrains. My 05 tahoe was 300hp factory rated and seemed to run good. I would love to do a LSx swap, these engines are VERY capapable as you know. My 355 sbc with 240+ duration and 4.10 gears with 42's and now an auto is not happy. lol. Thanks for sharing!
 
It still barks a 35" tire in second gear. I found the tow/haul wire to adjust the shifting separate from the 2wd mode.
That I will activate when it's in 4wd to allow for better shifting in 4low.
 
Did you ever get your shifting issues sorted out? I just helped a buddy SAS his truck (3 link/D60/etc) and he swapped to a 241, and it only has 1st and 2nd gear when he puts it in 4low. He hasn't figured out why yet
 
I have been helping out with the swap and wiring and it is a pain when you are talking 4x4. I'm in the middle of doing some more research to find a better solution than the tow haul enabler. Post up what you find also.
 
If you wired up a microswitch and installed it at the end of the transfer case shifter travel to 4 lo, then it could tell the computer when it's in 4 lo and you should be good to go. I saw it somewhere, but I can't remember who did it.

You would just need to identify what wires to tap into.
 
Done and it still shifts wrong in 4 low it seems to be doing the speedometer corrections in 4 low but still shifts are out of whack. That was the reason we hooked up a tow haul switch it has independent shifting tables that can be modified separately from the regular shifting. The idea was that when in 4 low we could activate the tow haul button and program the proper shift points. We got it all working and the shifts are better but very aggressive.

It seems to me there should be a separate table for 4 low shift points just as the tow haul, and 2 and 4 high. That is what i am trying to find out.
 
Wow props to you guys. Almost 6k and it still doesnt run right. I would be in prision for murder by now!! You guys are better men than me. Bravo. Love this concept but it seems like the 2wd guys have it way easier then us. This is the second or third build thread i have seen online where people have the exact same issue with 4wd. If my truck was a 75 or older i would go this route but since its a 86 and still tested for emissions i dont want nor need the headache. It runs good enough with the GM crate engine and i have had it up some steep inclines/declines and it has never died so i figure just leave it alone. Love the blazer though. Intrested to hear from the OP to see how this plays out.
 
I've had it out before up in Rowher Flats and it did well,just needed some trans tuning and adjustment.
The key to one of these swaps is the tuning,finding someone with knowledge[and a Dyno] who will walk you through until it's right.
Or buy the software yourself [which is what I should of done from the getgo] learned it, and did it all my self.
 
It seems 4 lo is now working properly just need a bit more tuning but the major issue is fixed by the tow haul mode.
 
Looks like I'll be rebuilding a front axle. I hit the woopty-doo's a little too fast last week and cracked the housing, made home though:doah:
 
I'm sure I missed it, but do you have emissions testing where you're at? If so, how did you (or do you plan to) sneak this by them?

Having just moved to Colorado, I'm new to the whole emissions testing thing so I'm very curious how these swaps go when emissions is involved.
 
El Jefe said:
I'm sure I missed it, but do you have emissions testing where you're at? If so, how did you (or do you plan to) sneak this by them?

Having just moved to Colorado, I'm new to the whole emissions testing thing so I'm very curious how these swaps go when emissions is involved.
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Emissions in CO is not as strict as CA. You should only have to pass a smog check. They dont really do visuals or anything crazy. Also, I believe as long as the motor is newer than the vehicle you should be ok.
By the way where at in Centennial are you? I grew up in Littleton. Most of my family lives up there still.
 
CherryK5 said:
Ha! Nice. Time for some bumps
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Yea, one of the things I'll be looking into when the new axle gets welded and installed. What stops I have aren't doing a whole lot.


And as far as emissions are concerned here in ca, My K-5 is a 1975:woot:Pretty much the smog cut off year,so I left the EGR and CATS off.
 
87K506 said:
Did you ever get your shifting issues sorted out? I just helped a buddy SAS his truck (3 link/D60/etc) and he swapped to a 241, and it only has 1st and 2nd gear when he puts it in 4low. He hasn't figured out why yet
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There is a wire you need to ground out via a switch while in 4 low. Its a wire that goes to the plug that went into the transfer case control module.
 
I would assume the easiest way for people to do this swap would be to simply use a 2wd engine and trans harness on your set up.

Bolt up a 4x4 drivetrain, ditch the 263 for a 241 and use the rear vss on the trans and move it to the t-case.


Or am I over simplifying it?

On my 07 I run a 2wd factory set up with the vss in the trans as it was stock. My speedo reads double but I have no complaints or reason to go faster than 65 in 4low anyhow.
 
xeong5 said:
How much mpg are you getting with the swap.
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It is a lot better than it was. I can't give you exact numbers [cause I don't have a speedo yet]
But I have went on trips where I have gased up at [before the swap] and now it takes less to fill it up.
Like from 11 gallons to 7:woot:thankyou overdrive!
 
supersize75k5 said:
There is a wire you need to ground out via a switch while in 4 low. Its a wire that goes to the plug that went into the transfer case control module.
Click to expand...

Its been done but still is not acting right, the speedo reads correct just shifts wrong, tuner claims there is no adjustment for 4 low shift points, they are the same shift points as 4 hi or 2 hi.

We hooked up the tow/haul wire and switch these shift points are adjustable to what ever you want, so when in 4 low the tow haul mode is activated there fore correcting the shift points. It works but shifts crazy hard still needs a little tweaking.

Game plan is to buy hp tuners and do it my self as the tuner seems to not want to take the time to get it perfect.
 
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