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L18 8.1L swap resource thread

Blue85 said:
Anybody have a good site to look up exploded diagrams and part numbers?

Right now I'm looking for the gaskets that go at the ends of the giant iron coolant crossover tube and can't find them listed anywhere.
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I used these.

ACDelco 12571593
 
#Burbslut said:
I have to say, what a amazing thread this is.

After going back and forth on what I was going to do to my 87 6.2/400/208 V20 Burb. I made a decision and joined the 8.1 club in November. Since then, I have been amassing parts and collecting as much info as I can. I’m not sure if there hasn’t been a question that popped up in my head that hasn’t been answered here.

I actually wasn’t even considering a 8.1 until I reached out to a friend that owns a fab and motor company in Gilroy Ca. I had picked up a 6.0 ls and was on the hunt for some good used parts. After a few conversations and months of hustling, I picked up my Tilden Motorsports 8.1!

I originally was going to put a tbi454 in, then a 6.0 ls. But I really wanted the BBC. I got the best of both worlds.
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Cool! Nice score :waytogo:. You won't be disappointed

Blue85 said:
Anybody have a good site to look up exploded diagrams and part numbers?

Right now I'm looking for the gaskets that go at the ends of the giant iron coolant crossover tube and can't find them listed anywhere.
Click to expand...

These guys have a decent online catalog. You can also search by Mercruiser 8.1L and download a pretty handy engine parts PDF. At least you could 10 years ago. I haven't looked lately
 
I have a new project starting soon. 2004 8.1 going in a 75 k10 4wd. Current motor 454/turbo350. I am still deciding how deep i am going. Transmission is next decision. Does anybody have pictures of what it takes to put a Allison in one of these truck without the body lift? That is what i currently have so that is option 1. I want an automatic so next option will prolly be the 4l80. deciding on doing axles now or later (currently 12bolt/d44) going to d60s with a drivers side drop to use the newer transfer case for either transmission. cheaper and easier to find a dana 60 with drivers side drop as well.
Mostly looking for pics of an allison in a truck now to decide how much sheet metal work is required.
I have only made it about 5 pages in this thread so far, sorry if they are on there somewhere.
Thanks in advance
 
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Lp1985 said:
I have a new project starting soon. 2004 8.1 going in a 75 k10 4wd. Current motor 454/turbo350. I am still deciding how deep i am going. Transmission is next decision. Does anybody have pictures of what it takes to put a Allison in one of these truck without the body lift? That is what i currently have so that is option 1. I want an automatic so next option will prolly be the 4l80. deciding on doing axles now or later (currently 12bolt/d44) going to d60s with a drivers side drop to use the newer transfer case for either transmission. cheaper and easier to find a dana 60 with drivers side drop as well.
Mostly looking for pics of an allison in a truck now to decide how much sheet metal work is required.
I have only made it about 5 pages in this thread so far, sorry if they are on there somewhere.
Thanks in advance
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Sounds like a fun project. Neither the Allison 1000 or ZF S6-650 manual trans that were found behind 8.1Ls will fit an old square without a body lift or body mods. And, you’re not really missing anything as the Allison is nothing but a power eater and fuel economy destroyer behind an 8.1L. If you must have an automatic a 4L80E would be the transmission of choice. 4L80Es were the transmission behind 8.1Ls in Suburban’s, Avalanches and G-Vans so they are plenty capable of being up to the task.
 
Thanks for the reply. I believe I would rather go with he 4l80 and save all the body work.
Hopefully I can sell the Allison and and put a dent in a building a 4l80.
Is the physical size of the 8.1 much different then the 454?. I know my headers will bolt on, I am just curious about frame clearance issues since they are already pretty snug fit.
Any body running a 208 t case with the 4l80 behind one of these? Will it hold up? I may go that route to delay the axle swap to 60s and maintain the passenger side drop and preserve some funds and speed up the process a little bit.

I am still reading for info, but what Are some must do items to do before dropping the engine in? I plane to leave stock for now and save any mods for down the road.
Thanks again for any advice
 
Lp1985 said:
Thanks for the reply. I believe I would rather go with he 4l80 and save all the body work.
Hopefully I can sell the Allison and and put a dent in a building a 4l80.
Is the physical size of the 8.1 much different then the 454?. I know my headers will bolt on, I am just curious about frame clearance issues since they are already pretty snug fit.
Any body running a 208 t case with the 4l80 behind one of these? Will it hold up? I may go that route to delay the axle swap to 60s and maintain the passenger side drop and preserve some funds and speed up the process a little bit.

I am still reading for info, but what Are some must do items to do before dropping the engine in? I plane to leave stock for now and save any mods for down the road.
Thanks again for any advice
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You shouldn't have a problem selling an Ally wtih plenty money to spare to build a nice 4L80E. If the engine is a good runner, I’d just do a full reseal (front and rear main seals, oil pan, timing cover and intake gaskets) and call it good. Definitely want to replace the crank sensor with a genuine GM part while the engine is out as you won’t be getting it out once the engine goes in the truck. Don’t settle for some Huy Fong Ching Chong crank sensor from Amazon for that one.
 
Larry said:
Correct, the bolts for the alternator are 10 miles long and go through the alt straight into the head and are not the same as pickup truck bolts that I know of.

Try these….

12552096 x4 - BOLT, Engine Coolant Pump (3/8-16 X 2 1/8)

11516367 x3 - A/C – P/S bracket bolts

12555610 x1 - A/C – P/S bracket stud

12580771 or 1258774 – Not sure which of these is the idler for A/C delete. You probably need both anyway.

You can find most of these part numbers here and search by a 2002 G-van with a 8.1 or a 2002 3500-HD (GMT400 truck) with an 8.1
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Hey Larry, thanks again for all the awesome info.

I didn't see it, but most likely I missed it somewhere.

Do you have a part number for the A/C pump mounting bolt(s) part number? I have the upper drivers side a/c pump location.
 
Lp1985 said:
Thanks for the reply. I believe I would rather go with he 4l80 and save all the body work.
Hopefully I can sell the Allison and and put a dent in a building a 4l80.
Is the physical size of the 8.1 much different then the 454?. I know my headers will bolt on, I am just curious about frame clearance issues since they are already pretty snug fit.
Any body running a 208 t case with the 4l80 behind one of these? Will it hold up? I may go that route to delay the axle swap to 60s and maintain the passenger side drop and preserve some funds and speed up the process a little bit.

I am still reading for info, but what Are some must do items to do before dropping the engine in? I plane to leave stock for now and save any mods for down the road.
Thanks again for any advice
Click to expand...
I would do the ORD crossmember and a 1" body lift , just makes life easier.
 
#Burbslut said:
Hey Larry, thanks again for all the awesome info.

I didn't see it, but most likely I missed it somewhere.

Do you have a part number for the A/C pump mounting bolt(s) part number? I have the upper drivers side a/c pump location.
Click to expand...
Here you go…. 11516360

This site HERE is your friend for looking up part numbers
 
#Burbslut said:
I didn't find the info there.

How's about engine to trans bell housing bolts?
Or just a length. I know they are 10X1.50
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Whoa? :dunno:

Home > Chevrolet > Silverado > 2001 2500 HD 4WD > Tranmission - Automatic > Transmission To Engine Mounting > 15724226 STUD, Transmission Mount and Support. Required Quantity: 06

In true GM fashion, their naming nomenclature doesn’t make it easy on anyone
 
Larry said:
Whoa? :dunno:

Home > Chevrolet > Silverado > 2001 2500 HD 4WD > Tranmission - Automatic > Transmission To Engine Mounting > 15724226 STUD, Transmission Mount and Support. Required Quantity: 06

In true GM fashion, their naming nomenclature doesn’t make it easy on anyone
Click to expand...



Dang it, I stand corrected..........
Thank you.
 
I'm trying to only ask questions that are helpful to other 8.1 square body swaps.

What is everyone using for the a/c compressor fitting? Id like to try and just adapt my stock lines if possible.

AC compressor.jpg
 
#Burbslut said:
I'm trying to only ask questions that are helpful to other 8.1 square body swaps.

What is everyone using for the a/c compressor fitting? Id like to try and just adapt my stock lines if possible.

View attachment 331197
Click to expand...

What you pictured there of my K10 is not the best way to do it but it happens to be the most cost affective. That is an S10 4.3L header pipe that I cut and used compression fittings. It works but isn’t a tight seal and the A/C needs topped off every spring. When I first started using the H6 compressor back in 2003 on my 454 with 98 L29 brackets, there were no neat aftermarket A/C blocks to be bought. These days there are a few options. Someday I need to redo the K10 badly.

My Suburban, on the other hand, had a much better set up although Napa ran out of the right size elbows that would allowed the hoses to lay cleaner instead of on top of each other. It’s still a nicer setup than the K10 and doesn’t leak. The A/C Block is AA0443 from Air Parts, Inc but this one looks to be the same. Vintage air also has another block where the connection comes straight out of the top instead of front but I wasn't sure if that setup would clear the hood or not once the lines were screwed on.

18684269204_b1bf808ec8_c.jpg


19119162568_83261bdcd1_c.jpg
 
#Burbslut said:
I'm trying to only ask questions that are helpful to other 8.1 square body swaps.

What is everyone using for the a/c compressor fitting? Id like to try and just adapt my stock lines if possible.

View attachment 331197
Click to expand...
I used a stock 8.1 line from Rock Auto and had the local A/C shop crimp new hose with the old lines

IMG_0928.JPG
 
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