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'71 k5 "Cowboy Cadillac" LM7 swap... Over the hill

TruckinFool

TruckinFool

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So this was supposed to happen eventually but I was sitting here about to drop $500 on getting the old 350 daily driver worthy and came across a cheap/local LM7 swap out of an 05 with 40k miles so jumped on it. Original plans were an LQ9 but eh.. sh*t happens...:doah:

Due to no job and low funds this will be happening a little bass ackwards

Here's the rough plan for now:

- Engine:
05 yukon 5.3l LM7 40k miles

- Mounts:
???

- Wiring:
Might do this myself. Checking pricing to see if its worth the investment of time. Would like to rewire the chassis harness either way.

- Driveline:
Stock th350/NP205.

This is temporary, I want a 4l60e/241 behind it but cant manage it at the moment. If the 5.3 doesn't cut it I'll sell all of the above for a 6.0 setup.

- Shifter:
Lokar floor mount cable shift. (Current column shift is FUBAR and cant find parts. Hopefully I can reuse this on the 4l60e later?)

- Gauges:
Home brew Autometer Gauge cluster

- Tuning:
HPtuner

- Fuel:
??

- Cooling:
??

- Gears:
??

- Lift:
4" lift of some kind? Most likely 4" ez ride up front and shackle flip rear. Greasable bushings all around. Tires will be 35's max


I'm learning about these trucks/motors as I go so anything left open means I still haven't ironed out a plan.

I'm very open to and would really appreciate any suggestions!


Some pics:

picture.php

First fill up on the way home.

picture.php




PS

This dirt driveway situation is going to SUUCK... It took about an hour just to get the motor safely out of the bed. I'll snap a pic tomorrow, should be good for a laugh.
 
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awesome good luck with your swap. I just got done pulling a cummins out in the backyard in some grass. All 6 of the hoists wheels sunk in about 4 inches haha.
 
Good luck... not too many of us left out there with 71's... keep it alive. Mines rattle canned and had only been in a shop once since i've owned it... and that was a friends to check why the carb wouldn't open the secondaries... gotta love workin in the dirt - builds character
 
$500 WOW! :eek1: I need to find one like that, and it looked clean at that. I just put a 350 in mine and paid $400 for it. I was at the local swap meet and saw a few Ls for about $1200. Good luck with the swap. :waytogo:
 
Looking forward to this! Good luck! I know how you feel about the dirt driveway. Tough to choose if dirt or gravel is better...
 
TruckinFool said:
PS

This dirt driveway situation is going to SUUCK... It took about an hour just to get the motor safely out of the bed. I'll snap a pic tomorrow, should be good for a laugh.
Click to expand...


Yes, yes it will suck. But just think about all the charactor you'll be building along with your truck build...:haha:

Having to work in the dirt these days myself, I like to use sheets of plywood both under the rig and for setting parts on. every little bit helps...
 
Ah yes, Character... I keep telling myself that haha

Shot of the "workshop" and yes thats my engine Tee Pee in the background... Don't sweat.. haha
picture.php


BTW truck set me back $2500 not $500. I wish though! The $500 was going towards upgrades to the stock 350. Instead picked up the LM7 for $950 which hopefully after some blood and beers turns out to be a smart move.

Power washing the engine bay today, I'll snap some pics/video of the engine running and maybe start pulling it this afternoon.
 
Got me a 71 too, i'll be watching your build, i'm installing a LQ4 (6.0) in mine with the stock 4 speed. Mine will keep the stock appearance as far as paint and and interior but it will have 4 inch lift with 33/1050's on stock wheels and hubcaps.
 
So I was checking over all the electronics. The engine harness and pcm are correct but I'm not sure the guy I bought this from was given the right DBW pedal and tac. There's a pic below of what I have. The sensor itself on the pedal looks right but the whole assembly is odd and I cant find a match. The "TAC" looks odd as well? Both are "Supposed" to be from an 05 yukon.

Anyone seen these before?
picture.php


If these are wrong I'm told any GenIII truck pedal/tac will work?
 
The other truck pedel and tac SHOULD work still i would think. My hunch is that the pedel assembly is from a truck with adjustable pedels... TAC almost looks wireless?
 
Didn't even think of that, Good call on the adjustable pedal. Weird thing is its only got about 1/2" of movement between 0 and 100%. Seems like the pedal would be insanely touchy?

On the backside of the "TAC" its got a plastic ring built in as if a tube is supposed to pass through it and the tab you see is a half circle like it should have a ziptie holding itself to whatever tubular deal is running through. Weird... Im not really sure its a TAC? No helpful markings on it and it seems more like an amp meter or something for a battery cable.


Knew id hit a bump in the road somewhere...
 
TruckinFool said:
Didn't even think of that, Good call on the adjustable pedal. Weird thing is its only got about 1/2" of movement between 0 and 100%. Seems like the pedal would be insanely touchy?

On the backside of the "TAC" its got a plastic ring built in as if a tube is supposed to pass through it and the tab you see is a half circle like it should have a ziptie holding itself to whatever tubular deal is running through. Weird... Im not really sure its a TAC? No helpful markings on it and it seems more like an amp meter or something for a battery cable.


Knew id hit a bump in the road somewhere...
Click to expand...

That sounds like a peice that gm put on the cables of the newer trucks and SUVs and dosent look like a tac .

As far as the pedal it does look like the adjustable pedal model I'll look at my wides 04 in the morning it's got adjusable pedals to confirm. I'll also try and get a pic of the tac module.
 
Might be wise to speak to these guys about the throttle as well as other mods http://www.pacificfab.net/.
Or try http://www.hotrodlane.cc/.
Both are well versed on the LS conversions.
I'd shop around for a wiring harness.A lot of folks make them to your specs. All the while,install your engine and plan out where you will want to place things ECM,MAF,fuel relay, fuse box etc. Things like this planned out before getting your harness makes your install go so much faster and easier.
I speak from experience:whistle:
 
tac pics

Sorry it took so long but heres some pics.
Here are the plugs on the tac module
tacplugs.jpg

here is the whole module
tacmodule.jpg


Heres the adjustable pedal.
tacpedal.jpg

tacpedal2.jpg

I think that you can still use the adjustable pedal just build a solid rod or bracket to replace the adjuster seen above.
 
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Thanks for the pics, and links buefchris just came on to check for them. I think I'll do the harness myself so I can use the money subbing out more non driveway friendly stuff.

Got hosed on the TAC module for sure. I'm thinking I might just grab a complete DBW setup with the regular style pedal. Looks alot easier and cleaner to install, although adjustable pedals in a 71 blazer would be pretty pimp! haha

Got a new TC on order and I'm planning on buying an early blazer poly mount kit and modifying the cross bar to accept the LS pan. Hopefully motor will be in sometime next week.

Having trouble figuring out what to do about the fuel tank? I would really like a baffle or foam filled tank that will still hook up to the stock fuel filler. Anyone know if the later TBI tanks will bolt up to pre 72?
 
Got the new TC in yesterday and set it up against the LS flywheel. Here's a shot of then together. You can see what needs to be ovaled out and length of the snout incase anyone's interested. To solve the short snout issue there are basically two options when using this combo. A friction fit crank extension or a bolt in style one which also requires longer flexplate bolts. Both can be had from Summit. (I'm told the bolt in styles are just copies of the GM adapter used when mounting a 4l80 behind an LS with short crank.)

picture.php

picture.php
 
Just go buy the one from gm and get the longer bolts from them too the spacer came in trucks with a 6.0 and a 4l80e. You don't need to waste your money on the arp bolts the gm bolts are more than stronge enough and come with the loctite and sealant already on them. ThAt's what I used and it worked great.
 
Yea, thats the route I want to go. I tried calling the parts guy the other day but he didnt know his D from his A so I gave up trying to explain. Do you happen to remember the cost and/or part #'s?
 
Got the part numbers for you the spacer is
12563532 and I think it was like 35 bucks

The bolts are lilke 5 bucks a piece but not sure I got them free cause was working at a clutch business at the time.
Bolts: 12563533

Since you got the the dished flywheel you would want to bolt the flywheel then the spacer to the crank.
Hope it helps let me know if you need and more info.

Also is that a black lab I see in one pic.
 
You the man dude, thank you.. seriously.

And yea that's my bud Tye. He's used to pickup beds so he's the k5's #1 fan lol The old lady will come around once its not getting 6mpg and seat belts hah
 
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