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L18 8.1L swap resource thread

centexk5

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no one said im the sharpest at this lol. im a computer tech...

anyway.. ill get squarebody headers then.

also figured out fan hitting member.. another not the brightest moment... i dont normally pull engines. bolt on back was too long and hit cab. was keeping engine up. sawzall ald when it cut.. entire engine dropped more than a half inch...
was either cut and remove with pliers or yank engine...

lessons learned for when we do 5.3L in my sons nissan 350z and twin turboing..
Please post a build on that Z. I was getting ready to pull that trigger on mine when we found out we were pregnant with our first. I loved my Z.
 

ZooMad75

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I'm running that 5-blade steel fan. It's GM 15767319 and shown for all the years of 8.1L.

Going back through the catalog it shows different images depending on which group you pull it up in. On the group for the cooling fan it shows 9 blades but the water pump behind it has the angled outlet for the g-van/workhorse/medium duty water pump. Go back into another group and it shows the correct water pump and 5 blade fan.

The images are wrong depending on where I look.
 

SpeedlabDan

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Change subject real quick, here's some "custom cruise 3" info for potential hookup to the vortec harness. Howell included the 4 tagged wires pictured for use with cruise. A good friend of mine I graduated with is part of American Autowire out of Bellmawr NJ near me who provided me with the schematic and some insight for the gm Sq body side of the controls.

Pictured is also the plug sides of the stalk to factory harness plug that will be used to splice in the efi side.

Red- set/coast
Green- brake input
Yellow- resume/accelerate
Blue- 12v ignition

The cruise options were offered by third party so color codes changed to the plug side which go as fallow:

Grey to green
Red to dk blue
Yellow to dk green
Blue to pink

From there the green, dkblue, dk green, and pink are spliced to the corresponding four wires from the efi harness.

Unfortunately, in theory this will work but I can't test it yet.

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2Dogs

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Knock sensors getting in the way with your headers? @#Burbslut gave me the tip on using different thread size knock sensors (Standard Motor Products KS63).

New location, no codes :pimp:
smallks-jpg.360386
 

Larry

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Knock sensors getting in the way with your headers? @#Burbslut gave me the tip on using different thread size knock sensors (Standard Motor Products KS63).

New location, no codes :pimp:

I wonder where he acquired such information :thinking:

That is tidbit of information is on page 1 of this thread along with the part number you need and its not just for trucks running headers, its pretty much for everyone swapping them into a square regardless of headers or manifolds
 

2Dogs

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I wonder where he acquired such information :thinking:

That is tidbit of information is on page 1 of this thread along with the part number you need and its not just for trucks running headers, its pretty much for everyone swapping them into a square regardless of headers or manifolds

I have read through this multiple times, missed seeing that. Let me know if you want me to delete. Thanks to you, belatedly! One of these days I will contribute original information.....
 

SpeedlabDan

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Finished wiring the cruise and the change is I had to add another brake lamp switch in the cruise control location to interrupt the signal. Since one side was switched by the stalk on/off it needed its own switch.
 

SpeedlabDan

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It just occurred to me small block Ls flex plate bolts need to be thread sealed. Do our L18 8.1L bolts have the same design being the one piece crank seal? I changed my seal carefully and it wasn't leaking till it was fired again.
 

Larry

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It just occurred to me small block Ls flex plate bolts need to be thread sealed. Do our L18 8.1L bolts have the same design being the one piece crank seal? I changed my seal carefully and it wasn't leaking till it was fired again.
I don’t follow the LS world enough to know what you’re talking about by “Thread Sealed”. But, probably not…….when you received new 12563485 bolts from GM they have a thread locker patch on them and that’s it. Not sure if that bolt part number is the same for automatic flexplates as it is for manual trans flywheels.


s-l300.jpg
 

SpeedlabDan

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Just thought it may be worth discussing when the engineering could be shared as early Ls engines were known for leaking this way
 

Larry

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Just thought it may be worth discussing when the engineering could be shared as early Ls engines were known for leaking this way
Leaking oil out of a blind hole in a crankshaft? I guess I’m not follow how that is even possible :dunno:

8.1s did have an issue with the intake bolts that were threaded into open holes into the intake valley on early engines that caused oil consumption, but not leaks. Around 02 or 03, they made that hold blind to avoid the oil from creeping up the intake bolt
 

SpeedlabDan

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Leaking oil out of a blind hole in a crankshaft? I guess I’m not follow how that is even possible :dunno:

8.1s did have an issue with the intake bolts that were threaded into open holes into the intake valley on early engines that caused oil consumption, but not leaks. Around 02 or 03, they made that hold blind to avoid the oil from creeping up the intake bolt
Remember the bulletin about the intake but apparently the crank holes in Ls cranks are not blind. I didn't think to check when I installed my new flex plate after installing the main seal. I still have a slight leak at the bell so before I drop the entire trans etc I thought I'd check
 

Larry

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Remember the bulletin about the intake but apparently the crank holes in Ls cranks are not blind. I didn't think to check when I installed my new flex plate after installing the main seal. I still have a slight leak at the bell so before I drop the entire trans etc I thought I'd check
That’s the craziest thing I’ve ever heard but Google says its true. It looks like there are some threads out there on the interwebs of guys having such an oddball oil leak on LS engines. I have a L96 6.0L sitting here on a stand that has blind flywheel holes in the crankshaft. That leak must be something with early ones :dunno:

More of a reason to stick with a genuine BIG BLOCK! :waytogo:
 

SpeedlabDan

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Worth askin lol guess I'll be pulling my trans and using an installer for the next main seal. I even packed the spring with grease the old school way
 

sweetk30

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friend of mine scored a 05 2wd 8.1/6 speed stick truck for the drive line .

he wants to know specifics on making the trans take a t-case or just go divorced ?

and who is a good solid place to send harness and computer to to make it stand alone and a little power bump .
 

Larry

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friend of mine scored a 05 2wd 8.1/6 speed stick truck for the drive line .

he wants to know specifics on making the trans take a t-case or just go divorced ?

and who is a good solid place to send harness and computer to to make it stand alone and a little power bump .
Wow, that’s a pretty rare combo to stumble across. I don’t know what it would take to convert a 2wd ZF to a 4x4. It maybe as simple as changing the rear cover, adding a different tailshaft or as big of hassle as replacing the main$haft, etc. Some parts catalog researching and part number comparisons need to be done to determine that. In the end, a divorced transfercase would probably be the hot ticket.

As far as a harness, I’m not a fan of paying anyone to rework them. Some guys have done it with great success and others have been a total nightmare. My preference would always be to start with a brand new stand alone harness from someone like Howell, etc.

Here is a picture of the ZF in my Silverado when I popped it out a couple years ago to replace the rear main seal. That trans is huge!
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