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Another LS3, T-56 swap into 1981 C3

72K views 243 replies 26 participants last post by  AGVI  
#1 ·
Greetings to all - I've been a member here for about a year but haven't posted anything until now. I know there have been quite a few threads regarding the LSx swap into a C3, but I thought I'd add my experiences to the wealth of information here!

I actually started my build a little less than a year ago, just in time for the Photo Bucket Phiasco that wiped out a lot of info just when I needed it the most! The car was kind of a "barn find", an 81 4-speed with 46K actual miles. No damage, no missing parts inside or out and most surprising no rust other than some surface rust here and there on the chassis. It was the condition of the car that prompted me to do a full resto-mod.

This is my first attempt at posting with pics by uploading them to DC. I'll probably mess up quite a bit here at first so bear with me! Advise and suggestions are welcomed! So here we go....
 
#5 ·
Well, it worked but it is a little clunky. I noticed something about a limit of 60 photos in a DC album. Don't know if you can have multiple albums with 60 pics each.

Meanwhile, I'll proceed with this method for the moment.

As I mentioned, I started this build last spring but I'm not done by any stretch, so I'll try to make several posts per day until I get caught up to the current build status.

Oh, and I want to give credit where it is due. This forum was a huge help in planning before PB went dark, so I hope that I can offer some help/ideas also. I'm not going to post every step of every process I did, but I welcome any questions/comments.
 
#8 ·
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Click on Direct Link on IMIGUR.
Copy it the link.
Then go to Post reply on DC. Click on it.
The 3rd ICON on top of the Tool bar area from the far right, looks like a small mountain top, that is the Tool to click on next.
Click on it.
It will say Please enter your URL image.
Hover over it with your mouse Cursor.
Without touching the keyboard on your PC or laptop Paste your Direct link from IMIGUR, Your Picture.
Then click on Ok with the your Mouse Curser.

Add more photos if you want to in the same manner.
When done you can preview the post.
Then Click on Submit reply.
 
#13 ·
Here's 3 pics I took tonight to give an idea of where I am on the project.

LS3 from 2010 SS Camaro
T-56 6 speed and bell housing from 98-02 F-body
Speed Direct upper A arms
Speed Direct Steeroids
Modified water pump housing to clear upper A arm
Modified crossmember
Everything powder coated, dust shields & caliper bracket re-plated zinc chromate
All brake lines fabricated in house using stainless steel tubing
Body lifting fixtures fabricated in house for 2 post lift
Differential upgraded to 3:54 and rebuilt by V-tech
Trailing Arms rebuilt by V-tech
Composite rear spring by VanSteel
Custom fuel tank by VetteWorks (uses OEM pump mounted to the right of the gas tank filler tube
LSx adapter plates by VetteWorks
Rear half-shaft using Spicer non-lubricating (no zerks), a little hard to find but I have a partnumber if anyone is interested.

I have recorded many measurements and tool partnumbers for all of these mods so far. Engine/trans placement proved to be a bit critical. Accordingly, I have learned many things about what WONT fit! I am more than happy to share what I've learned with more in depth descriptions and photos, so if anyone interested just ask!




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#18 ·
Exhaust Pipe Routing

The 80-82 C3 with power seat has no space to run the driver side exhaust pipe without all of it hanging down lower than the frame. The factory setup was actually fake dual exhaust. The driver side exhaust crossed over to the passenger side and joined the passenger side exhaust. Then on the downstream side of the cat they split again and went out the back.

Does anyone have any pictures or descriptions of routing the exhaust on the 80-82 C3?
 
#20 ·
The 80-82 C3 with power seat has no space to run the driver side exhaust pipe without all of it hanging down lower than the frame. The factory setup was actually fake dual exhaust. The driver side exhaust crossed over to the passenger side and joined the passenger side exhaust. Then on the downstream side of the cat they split again and went out the back.

Does anyone have any pictures or descriptions of routing the exhaust on the 80-82 C3?
The 80-82 looks nice with side pipes.
Be something unique LS Power.
 
#21 ·
I used an 80-82 cross-member under my 77 for my LS transplant . I read that the 4L60 bolted straight on to it , well it did after I made a new tongue to suit :laughing: I used it because the 77 cross-member has the two holes but the position of the 4L60 pan would have meant some tight turns in the pipes which I could do with out .

I am running twin pipes and had to mod the cross-member to suit .


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just an idea , not sure about your lower seat issue will affect it.
 
#22 ·
You have a clean setup there, I like. I haven't done much with the body yet been focused on the chassis/drive train. Couple of pics below show the problem caused by the power seat pan on the driver side. There is no possibility of running the pipe under the driver seat pan without it drooping down below the frame, so that's not a viable option. I think there may be just enough room right behind the x-member to divert the pipe over to the pass side, then cross back over before exiting at the rear. Failing that, I suppose I could ditch the power seat although I've been told the manual seat tracks for 81-82 are almost impossible to find. That combined with fabricating a new seat pan make that a possible, but not desirable option. If all else fails I guess there could be sidepipes in my future but they aren't my favorite. I also put a clearance relief in the stock x-member that mirrors the one on the pass side. I originally was going to use the hacked up x-member as a template to fab a new one but may just use it anyway. It'll look a little better after powder coat.


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#24 ·
yeah I see your problem ,and dilemma to fix .

I would like to hang on to the creature comforts inside personally so I would look at different exhaust routing .

If you weren't against side pipes it wouldn't be a problem I guess , sorry I don't have any real help to offer , only just a crazy idea of going single 3 inch and back to twin (kind of like ) as per factory set up , but that would probably drone real bad.
 
#27 ·
After talking this over with a good friend with a lot of fabrication experience, I've decided to fabricate my own system using one (or more) of the stainless steel 304 alloy kits that are available. I'll be using a pre-fabricated "X" pipe along with the mandrel bent curve sections. I'll need to brush up on my TIG skills, if I have any! More to come, I'll make posts of my progress when I get to that point.
 
#25 ·
C3 Body Lift

I've had several people ask about the body lift adapters I made, so I'll share here.

However, a word of caution is important;

***NEVER ATTEMPT TO LIFT THE BODY WITH THE CHASSIS ATTACHED!!

***THE BODY MOUNTS ARE NOT DESIGNED TO SUPPORT THE WEIGHT OF THE CHASSIS! IF YOU TRY TO LIFT THE ENTIRE CAR THIS WAY, IT IS PRETTY MUCH GUARANTEED TO DAMAGE/DESTROY THE BODY!!!

*** YOU ASSUME ALL RISKS IF YOU MAKE AND USE THE ADAPTERS!!!

Ok, with all that out of the way, when I first lifted the body off the chassis I used the hooks/straps available from several of the Corvette specialty suppliers. They worked, but it wasn't a confidence builder for sure. Plus it's hard to work on the body with it dangling and swinging around.

I decided it would be better to fabricate some kind of adapter to put on the lift arms. So I wound up with the "buttons" that drop into the lift arms, a 3/8" plate to weld the buttons onto, and a 3/16" blade that would fit between the frame rail and the birdcage "channel".

If you try this be sure that the weight of the body is supported by the top of the "blade" where it contacts the birdcage channel, NOT the lower edge of the body!

This setup works very well and supports the body firmly and securely. I have CAD drawings that I made for my Forward Lift. If anyone is interested in the drawings let me know.

And BE SAFE above all else. These adapters are designed with a substantial safety factor but if you are not confident with your welding or fabrication ability find a friend that is. Again, I ASSUME NO RESPONSIBILITY for the use of these adapters
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#28 ·
Shifter position

Ok, got the American Powertrain shifter set up, the shifter handle will mount on the left side of the stub. Very close to the ideal position. The AP shifter is very short throw and has independently adjustable tension for the right and left gates. A short shifter handle with a slight angle back should be about right. LS3 with T-56.

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#31 ·
Vintage Air Front Runner

After a lot of head scratching I finally gritted my teeth and went with the Vintage Air Front Runner setup. It seems to have one of the most compact systems. One thing of note however, the troublesome heater hose outlets are about 1/4" LOWER than the stock water pump from my donor car, 2010 SS Camaro. I will tap the small hole and use an Earls AN connection. I will tap and plug the large hole, weld a boss onto the bottom of the casting and tap/thread for the fitting. Everything else looks like it will clear with ease. This is just a dry fit, that's why the pwr steering pump pulley isn't pressed on to it's final location.
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#33 ·
The upper A-arms are from Speed Direct. I also got the Steeriods from them. I'm also thinking that I'll probably wind up with their lower control arms with coil overs before it's all over. But I thought I'd wait and see how the ride height turns out. The lower control arm swap shouldn't be that hard with everything all assembled. I can imagine that the fitting moved to the bottom of the water pump thermostat would be a pain to get to. I'm planning to use a 90° NPT to AN fitting. Also fabricating a boss to weld onto the bottom of the housing to ensure enough material to get good thread engagement. Would love to hear any experiences you have had with that arrangement!
 
#35 ·
EVAP System Advice

Seeking advice. I'm at the stage where I'm firming up my choice of ECM. I already have a new fuel tank/pump system from Vetteworks but I'm wondering about the EVAP system. At the moment my favored plan is to use the GM Performance ECM kit, but in studying the I/O I'm not seeing any provision for a signal to purge the EVAP system like on the stock system. Looking for recommendations here from those of you that have done a similar swap. The options I have range from eliminating the EVAP system altogether to a fully functioning system like a stock system. Will appreciate input!