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1979 LS3 Swap....it's begun

36K views 127 replies 26 participants last post by  Hrdc0r19 
#1 · (Edited)
Thanks to you guys here who have posted and a few guys I know I've started this project. I just sold my perfectly good drivetrain to a local C3 guy (383 stroker motor (with a bunch of goodies), TCI th350 trans w/b&m stall, OBX side pipe headers (kept sidepipes and mufflers for LS engine).

I'm planning on the LS3 525 crate motor with a 4L70e trans and stall. I'll also be going installing a vintage air setup along the way.

Here's some pictures from a few days ago. I'm waiting to hear back from a vendor before ordering the new setup. Hopefully I'll get it ordered next week and get some stuff moving here.

Out with the old....








 
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#3 ·
Consider me subscribed! Before you pull the pin on Vintage Air, you really need to look into Classic Auto Air beforehand. TXV metering, larger capacity evaporator (not siamesed) and the DER controller that takes the place of the stock clunky HVAC controls?
Yea baby. Perform due diligence before pulling the plug on Vintage Air. They simply cant touch the Classic Auto Air Perfect Fit series.
That said, your gonna love the swap, EVERYTIME you get behind the wheel!
Im running a blown LS with a beefed 4L60e, 3600 Vigilante billet and 3:73 cogs.
More fun than GM ever envisioned for a C3 Corvette!
 
#6 ·
Thanks for the information. I just emailed classic to see if they have any options available for my 79. Not sure what the differences would be besides ductwork. I'm very much looking forward to the LS drivetrain, ac and hearing an LS3 through sidepipes (hopefully it sounds good!)
 
#7 ·
I'm looking at custom image at this point for motor mounts and trans crossmember. Waiting on a little further information from them. Same goes for the the ls3/trans setup. I'm ready to order now that all the old stuff is out and sold!
 
#9 · (Edited)
A little bit of degreaser and pressure washing along with demo of the old ac setup and pulling dash. Engine bay will get some fresh paint and some new wiring harnesses (car had an engine bay fire atsome point and random splices in the engine harness, starter and ac). I think I will really like the additional space in the engine bay though.











 
#12 ·
I have about 90% of everything bought. Just waiting for everything to come in. Josh at CIC has been very helpful with getting me on the right track with the the LS3/525 ECM and going in the right direction for a harness.

I went with a 3500-3700 stall from circle d. E67 ECM harness from Tilden motorsports. LS3/525 motor and ECM, 4L70E trans, Motor mounts, crossmember for trans, engine accessories, tcm, new wilwood master cylinder and handful of other misc items are coming from CIC.

Here's some updated pictures. I tried my best to clean up the engine bay without going too overboard and ripping everything out. Filled in some holes and painted. I still have some touch ups but came out decent considering what it looked like previously.








souvenir from the old 383....my friend that helped e build the engine has the other.
 
#13 · (Edited)
classic auto air system came in last week. Hopefully it performs well and everything looks nicely laid out. Not sure exactly what to think about other than that. The company gave me a "custom kit" since they don't make one for the 79. I figured they would've started with the 68-76 kit and worked out the differences. (which maybe I should've just ordered the older setup and dealt with the differences myself, we'll see) Instead this way I had to make my own block off plates on the firewall. Not that hard and came out clean looking (see below).

I sent back the cheesy looking controller for the system. 1: cheesy looking 2: knobs are too large and you can't see the symbols, 3: way too large 4: goofy way of mounting.

I returned the defrost vent they send because it doesn't match up to the factory defrost and not close to the dimensions I gave for fitment. If they provide something close to the right size for the factory vent duct I can modify to make it work. Not a big deal and expected.

I also had to order some bulkhead fittings because with this kit they give you grommets to route your lines through the firewall. Kinda cheesy looking on this build in my opinion. I wasn't told this when I ordered the kit either.

I called last thursday to return the controller and get some bulkhead fittings and the guy never returned my call. I called the following tuesday and he said he received the controller I shipped back to them and will get the bulkhead fittings and new slimline controller out the following day (wednesday). I had to call again Thursday to check in on the status. I was really hoping to have these parts in by the weekend so I can get this thing tested and installed on the interior side over the 4th of July holidays. It's very apparent I'm going to have to call again today to confirm my parts were shipped. Sigh........






controller:



defrost vent sent (yeah, that's not gonna work):



The vent connections they sent over for the sides worked out perfect for my 79 dash:


the center vent will work just fine. Luckily I kept the factory ducts to modify for the center vents and defrost vents.
factory:


modified factory/CAA:
 
#16 ·
classic auto air system came in last week. Hopefully it performs well and everything looks nicely laid out. Not sure exactly what to think about other than that. The company gave me a "custom kit" since they don't make one for the 79. I figured they would've started with the 68-76 kit and worked out the differences. (which maybe I should've just ordered the older setup and dealt with the differences myself, we'll see) Instead this way I had to make my own block off plates on the firewall. Not that hard and came out clean looking (see below).

I sent back the cheesy looking controller for the system. 1: cheesy looking 2: knobs are too large and you can't see the symbols, 3: way too large 4: goofy way of mounting.

I returned the defrost vent they send because it doesn't match up to the factory defrost and not close to the dimensions I gave for fitment. If they provide something close to the right size for the factory vent duct I can modify to make it work. Not a big deal and expected.

I also had to order some bulkhead fittings because with this kit they give you grommets to route your lines through the firewall. Kinda cheesy looking on this build in my opinion. I wasn't told this when I ordered the kit either.

I called last thursday to return the controller and get some bulkhead fittings and the guy never returned my call. I called the following tuesday and he said he received the controller I shipped back to them and will get the bulkhead fittings and new slimline controller out the following day (wednesday). I had to call again Thursday to check in on the status. I was really hoping to have these parts in by the weekend so I can get this thing tested and installed on the interior side over the 4th of July holidays. It's very apparent I'm going to have to call again today to confirm my parts were shipped. Sigh........
Sorry to hear of your issues with the AC.
I'll still be interested in the finished look of the unit once it's all done compared with the Vintage kit. My unit hangs below the dash is slightly distracting.

But on a positive spin, your'e moving along nicely. Engine compartment looks good! that loom wrap will look good installed. Much more modern.
Keep up the good work!
 
#14 · (Edited)
Here's the block off plates I cutout for the old unit and blower. I also had a rusted out plate on the drivers side wiper area I went ahead and made.



Painted up and bolted on along with the slightly cleaned up firewall (still have to clean hinges):



[




 
#15 · (Edited)
I'm also redoing the wiring in the engine bay with some braided loom. I think this will last a little while and look nice.



new 79 engine harness with braid loom:
 
#17 ·
I'm also redoing the wiring in the engine bay with some braided loom. I think this will last a little while and look nice.



new 79 engine harness with braid loom:
First off, sorry about the issues on the AC. The kit I received had everything, including block off plates and blower motor covers. I especially like the D.E.R. controller, with one exception. It should have had a pushbutton to activate the compressor. As it stands, you have to move the slide off of the dash air setting to deactivate the compressor.

The only other issue I have had is my unit has a defective thermostat. It will freeze you cajones off, but in the process, it gets SO cold my ducts begin condensing on the outside.

Monday, I'm due to get the new thermostat in.

As far as your wire loom? Your gonna LOVE it over split loom. As far as how to seal the ends I used a product called F4 Tape. Heat resistant and self vulcanizing.

Keep up the good work!
 
#19 ·
I'd be having to modify the classic auto air or the vintage air system no matter which I went with. I never had the factory setup working so anything that blows cold air down here in the summer I'll be impressed.

Is the DER controller the factory looking one from caa that you have in your thread? It looks nice.

Did yours come with a fresh air block off plate? I'm curious if I can just shut the factory door or if I need to make block off plate for that too.

Beat ya to it! Already ordered some some f4 tape. Thanks. I was digging around on dc and found some posts on it with the braided loom. I can see my electrical tape stash won't be getting a lot of use.

Out stuff must have gotten shipped out about the same time. My new parts from classic auto are due Monday too.

I was gonna post a few more pictures but apparently photobucket is having some problems right now. Time to look for something else to use.

Ryan
 
#20 ·
I'd be having to modify the classic auto air or the vintage air system no matter which I went with. I never had the factory setup working so anything that blows cold air down here in the summer I'll be impressed.

Is the DER controller the factory looking one from caa that you have in your thread? It looks nice.

Did yours come with a fresh air block off plate? I'm curious if I can just shut the factory door or if I need to make block off plate for that too.

Beat ya to it! Already ordered some some f4 tape. Thanks. I was digging around on dc and found some posts on it with the braided loom. I can see my electrical tape stash won't be getting a lot of use.

Out stuff must have gotten shipped out about the same time. My new parts from classic auto are due Monday too.

I was gonna post a few more pictures but apparently photobucket is having some problems right now. Time to look for something else to use.

Ryan
Here's a decent shot of their new DER controller. Big improvement over the clunky factory control. As I've stated before, the biggest peeve is Classic not adding a pushbutton on-off for the compressor. You have to slide the setting off dash a tad, then it kills the compressor. If there was room enough on the controller, I'd add my own switch. Don't get me wrong, I'm used to the operation now, but it could have been a little more intelligently thought out from the git go.

On the fresh air issue or "Astro Ventilation" as GM like to call it. I used the spring to hold the flap closed, then I sealed it and the surrounding area with some leftover Stinger Roadkill.

I received the new thermostat yesterday, and will implement the replacement into the same time to radio and gauges come out for a single DIN radio with a flip out screen, new amp install and carbon fiber treatment.

Does it ever end?:crazy:

Nope....:thumbsup:
 
#22 · (Edited)
A few quick updates......I finally got to cover the rest of the firewall with some insulation. I did the rest of the interior of the car about 10 years ago and didn't bother with the firewall area. I used coolmat back then and upon patro46's mention and reading good reviews on it I used the stinger roadkill this time. It seems slightly thicker, and went in easily with a roller (minus a few cuts on my fingers). Installed some new ss brake lines for the front pass. & drivers side, ss braided brake lines on all 4 corners and painted the front calipers grey. Along with a bunch of other little items.


 
#23 · (Edited)
Now for the fun part.....the classic auto air system that was sold to me in place of a modified 68-76 kit hasn't worked out too well. I post this to help someone out in the future should they go with the caa system.

I've had to make my own block off plates (evap and blower). Pull measurements and make my own stand off brackets because the evap will not mount to the firewall without the brackets (other option would be to modify the firewall where the old ac harness/vacuum cables ran through, might save about 3" or so). After a few hours of mocking up stuff yesterday, I've come to realize the bulkhead fittings are way to large to use in our c3's. There's just not enough room. Heater hoses touch the evap/blower and there isn't enough room to route ac lines. Luckily I mocked all of this stuff up and didn't drill through my new block off plate only to find out none of the hoses fit. The guy I spoke with said "I thought it'd be a tight fit." He did say he'd sell me (of course) the hard lines that they supply with the 68-76 kits. This would have saved me hours of time and now money for shipping and whatever percentage they charge for their "restock" fee. I'll probably get a quote to have someone bend up some pieces locally and compare to try to save some cash.

It is what it is. Here's some pictures. The Bulkhead fittings and new slimline controller do look nice. I had to peel back the cover on the controller and realign it because it wasn't lined up straight with the buttons and the machined lip. the new defrost adapter looks like it'll sort of work. I'll have to be creative with it. Easy fix though and expected.

slimline vs normal controller:



mounted up, this is as far to the drivers side as I can manage.



mock up of firewall:




I'll also add the condenser fittings/lines do not fit either. Condenser is pushed as far to drivers side as possible and barely fits. Not acceptable at all.




ac bulkhead bulkhead fittings inside the car....can't go vertical with them, can't go down (you'll see them in the foot well) and obviously not enough room to go through the side. Thanks caa, this would've been a lot easier with the hard lines made for the corvette like I mentioned when I first called. It's only money and time time right? Definitely would've been easier starting off with a 76 kit and figure what fits or is the same and working our way back from there. Not to mention the money in shipping and their "restock" fee for something they recommend and say will fit.




I guess I'll get to the LS swap one day!!!!!.....at this point it seems like that'll be easier.

Ryan
 
#24 ·
Sub'd
 
#25 ·
little more work done along with some new presents:

new transmission crossmember came in, solid piece of work!


new harness from Tilden Motorsports. Made to go with the E67 ECM that comes already tuned for the ls3/525 gmpp. I'll be running the T42 TCM and have Tilden reprogram to work with the ecm and tire/rear end ratio. Everything looks like it's laid out nicely and the bussman fuse box is sturdy and on the smaller side.




My stall was built and arrived from circle d a few days ago.
 
#26 ·
I'm also reworking some of the interior so I can put a double din screen in my c3. Looks like I'll be sending off my gauges to have new bezels put on because the autometer bezels are starting to pit some. They're about 10 years old. I made a new plate for my gauges. the old lexan began to warp a little around the gauges a few years ago. It'll get a coat of black paint to help blend in with the interior for a stock kind of look.

old setup:


new plate cutout:



autometer gauge pitting:



I also plan to add a trans temp and a/f ratio gauge and maybe another of some kind under the hood cowl...should look nice. I'll probably go with white face gauges though.
 
#28 ·
Polished out the old OBX sidepipes with some classic chambered mufflers.


And these came in too.:partyon: Stainless Steel LS side mount headers from Josh at CIC. Welds around the flanges and o2 bungs look great! Hopefully I'll found out how they fit soon enough.





welds at the collectors are a little rough looking. Not sure if these are existing headers that are modified to fit the LS C3 or if someone else was welding on the collector. Overall though they look great!
 
#29 ·
Polished out the old OBX sidepipes with some classic chambered mufflers.


And these came in too.:partyon: Stainless Steel LS side mount headers from Josh at CIC. Welds around the flanges and o2 bungs look great! Hopefully I'll found out how they fit soon enough.
Nice!

You're going to love the sidemount exhaust on the LS!

Polishing the pipes they look great. What did you use to polish them?

Keep up the good work!
 
#30 ·
Thanks! Good to see your car coming together. I use white diamond or blue magic polish.

My trick is I use a rotary buffer with a foam pad. Harbor freight special with a hook and loop adapter along with 1 of their orange foam pads. Well worth the money.

 
#31 ·
Damn Ryan- really coming along NICE.

For some reason - I thought your car was an 82...and was the best looking 82 I had seen...so now it's the best looking 79!!!



After the paste and buffing wheel-I've had the best luck w/ Mother's wheel polish for the final- I used to be a fan of Simichrome- but Mothers wins every time!!!




An idea to finish the metal for your dash-

Hit it hit a belt sander- like 80grit- spray it w/ some primer and wet sand it (400-600) then shoot it with black paint- it'll look like a brushed finish.


 
#32 ·
Thanks Richard:D. ...yeah I swapped front end supports/brackets with an 81 years ago before paint. Glassed in some patch panels and new bumpers.

I may have to try the mothers when I run out of the others.

I like the dash with belt sander idea. I would've never thought of that. Nice, clean look. Makes you question if it came that way from the factory. Just what I like.
 
#33 ·
Looks like I'll be calling classic auto air again, again. Maybe this is normal operation? I noticed this during their calibration/function testing. The middle Defrost/floor vents (on the right side of video) do not close all the way when the controller is on the center /dash position. The opposite happens when controller is in defrost/floor position. I tried recalibrating the system a few times with the same results. This system is very simple and easy to setup and calibrate.



Here's the supply water valve in action. Valve changes position depending on how hot you set the heat temperature.

 
#39 ·
Looks like I'll be calling classic auto air again, again. Maybe this is normal operation? I noticed this during their calibration/function testing. The middle Defrost/floor vents (on the right side of video) do not close all the way when the controller is on the center /dash position. The opposite happens when controller is in defrost/floor position. I tried recalibrating the system a few times with the same results. This system is very simple and easy to setup and calibrate.

https://www.youtube.com/watch?v=ct5tvzHEeRg&app=desktop

Here's the supply water valve in action. Valve changes position depending on how hot you set the heat temperature.

https://www.youtube.com/watch?v=6RDi5MTEZTA&app=desktop
I spoke with classic auto air about this issue. I was told the opposite vents should fully close in either position. They said if it isn't sealing it should be all 4 on that side because of how the diverter is and that it is odd the 2 center vents are the only ones not sealing. I was told the little bit of air that may be coming out shouldn't be enough to cause any issues once installed.......I'm still hoping this product is solid and won't have any issues but confidence is dwindling.
 
#34 ·
LS3 swap C3

Blueday, I'm very glad I stumbled onto your post about an LS3 into your C3! I'm smack in the middle of a very similar swap, I'm doing an LS3 into a 1981 with a 6 speed manual. The car is going to be a "resto-mod". I'm pretty new on this forum so I hope everyone bears with me until I get more comfortable with it! I have lots of pics, not sure if I should "hijack" your post with my info or start a new thread, I would gladly accept guidance from the forum. Also some tips about posting the pics would be appreciated. Looking forward to exchanging information and things we have learned!
 
#35 ·
Blueday, I'm very glad I stumbled onto your post about an LS3 into your C3! I'm smack in the middle of a very similar swap, I'm doing an LS3 into a 1981 with a 6 speed manual. The car is going to be a "resto-mod". I'm pretty new on this forum so I hope everyone bears with me until I get more comfortable with it! I have lots of pics, not sure if I should "hijack" your post with my info or start a new thread, I would gladly accept guidance from the forum. Also some tips about posting the pics would be appreciated. Looking forward to exchanging information and things we have learned!
You're welcome to post here or PM me if you have a question on something, but go ahead and create a new thread and tell/show everyone what you're doing and so on. You'll probably get a lot more responses should you have any questions. And we like build threads!

I had a photobucket account but since they recently changed their policy I had to switch over to flicker for now. I had to go update all of my photos in this thread to the flicker account. Hopefully they don't decide to dramatically change their policy. Once pictures are uploaded, most sites have a share option with a link that has img tags on either end. Paste that into your post and it should show up.

Ryan
 
#36 ·
I was looking at the angle the refrigeration lines are leaving the firewall, and it looks like it might create an issue in clearance. If you LS swap it, you can see where the heads and manifold go, and it eats up more real estate than a smallblock did. I also relocated the receiver/drier. It looks packed, but if I ever decide to go with headers, they will fit, unlike the factory air.

Those headers. That chrome. Beautiful, functional eye candy!:partyon:

 
#37 ·
Patro,

I've seen pictures of some ls swaps with the factory ac equipment in the car (in the engine bay at least) and it looks really tight like you're saying. See my pics in next post of the heater hose/ac firewall connections (they look like they'll work, although they don't layout the same as yours do). I didn't ask for the corvette piping for the drier just because I'm not 100% sure where I'll mount it until I get the engine in and in the car. You have a lot going on in that area on your C3. I'm impressed you fit it all and looks clean. Thanks for the heads up, I'm trying to keep everything to the outside of the car as much as possible.

When you were calibrating the system, did you remember having any issues with the vents not fully closing off as shown in my video above?

Chrome? Those are stainless steel headers!:partyon:
 
#38 ·
The classic auto air corvette lines came in. I ended up having to make another set of brackets to offset the unit even further away from the firewall to let the corvette hard lines fit due to where they located the firewall fittings at. More time wasted that could've been addressed earlier on. As I suspected they do actually fit and look clean once installed. It's looking like this is turning into a classic auto air install thread and not an LS swap thread!:WTF

mock up yet again.


and put back in the car with holes drilled. This doesn't look like the same hard line layout as Patro has, but I don't think I'll have any clearance issues with the new ls3.





shown here is the clearance between the wiper arm area and the classic auto air evap unit.


And wouldn't you know it.....the c3 corvette condenser lines fit on another c3. The opening is a little different then what they show on the 76 C3 instructions but works. Much more professional looking compared to the "universal" kit I was sent.

 
#40 ·
I sure wish you weren't having issues with the Classic Air system. :thud:
For what it's worth, I only went with the cabin section of the HVAC system as I had already pretty much prepped the engine compartment with Sanden compressor and an upgraded condenser, as well as the PCM having control of the HVAC system, something I insisted upon, and this was an area I was on my own with, but fortunately, I love a good challenge, and have no regrets implementing this technology into the build.
All my refrigeration lines from the firewall out are "one-off", from the location of the receiver drier to the trinary switch location in the high side line. matter of fact, everything here deviates from anything Classic Air offers, as with just about everything on my car. It's so "one off" I feel for anyone behind me to have to dig in...:surprised
While your at it and already dug in with both feet, spend a little time researching the advantages of allowing your PCM to handle the AC control. You get a lot of control with stuff like throttle positioning, temp and pressure control and even voltage monitoring so if there is a charging problem, the PCM can sense the voltage drop and prevent rapid battery loss by preventing the AC from operating.
Most simply bypass these functions and pull the control wires from the PCM, probably only for fear of the unknown, but it's worth implementing into the build IMHO.
In closing, I tend to search for a silver lining to every dark cloud, and what I see here any way you shake with your time, bruised knuckles, ect. is a comfort solution you'd have NEVER had with a factory C3 air conditioner setup. Period.
You've already done pretty much what I have done, and the time you spent in the insulation department in your cabin will pay you back EVERY time you get behind the wheel on a hot summer day. No doubt about it.
I now am able to take my car out on days where it's too hot to drop the top and would have stayed home because of a sub par AC system. Sweating my butt off on a hot Oklahoma day in a C3 Corvette is now a thing of the past!:cheers:
 
#41 ·
Great thread there guy!

Part of the problem with both Classic and Vintage is that they have not come up with the correct setup for a 78-82 console. I have a 75 restomod project that I want to change over the interior dash to the later model version. The glove box change is the problem. I have not bought my air system yet until I see which company gets it right first.

BTW.....as far as using photobucket for pics.....I find that using the Manage Attachments feature already available here is much easier to use. You just load the pic from there. So simple a caveman could do it. Check it out.

Txs again for sharing. I have 2 projects that I was going to go old school 383 stroker SBC with but really tempted to go LS with one of them.

Good luck with your project

Dennis (Bman)
 
#42 ·
I agree, after going through most of this caa setup it doesn't seem like it'd take much to make some fittings/adapters for the factory defrost and center vents and the rest should be very similar to the other c3 setups. I would mind helping them out in the fitment area of things if they were to give me discount on the setup, but too late for that I guess.

:cheers:
 
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