Considerations for Next LS Swap
Thread Starter
Burning Brakes
Joined: Apr 2017
Posts: 877
Likes: 80
From: Frederick MD
Considerations for Next LS Swap
Good Afternoon All,
My '73 LS3 swap is on the road almost legally and I really like the way the engine runs and the six speed is nice for cruising on the highway. As I wrap up the project I am looking onto the next one, perhaps putting an LS in the NOM '75 coupe driver I have owned for a few years. It is an automatic and runs ok, but I will probably be itching for another project soon so I am considering another LS swap, I welcome any feedback on my thoughts below.
Scott
My '73 LS3 swap is on the road almost legally and I really like the way the engine runs and the six speed is nice for cruising on the highway. As I wrap up the project I am looking onto the next one, perhaps putting an LS in the NOM '75 coupe driver I have owned for a few years. It is an automatic and runs ok, but I will probably be itching for another project soon so I am considering another LS swap, I welcome any feedback on my thoughts below.
- Engine
- A corvette LS1 would be ideal, use the stock accessories.
- The LS3 I got was from a 2014 Camaro and I had to swap out for the CTS-V accessories, not a big deal, but that low alternator scares me if I ever have to replace it, will probably have to lift the motor, I prefer the alternator up high like the LS1
- The LS3 is realistically more motor than I need (but fun!), an LS1 will suffice.
- A corvette LS1 would be ideal, use the stock accessories.
- Transmission
- The car has the TH-400, which I know mates to an LS fairly easily. Should I do a rebuild on it, have somebody rebuild it (can you find anybody to do that nowadays) buy a rebuilt one, or consider a newer auto transmission as part of the swap?
- What is involved with a 4L60 swap? I will not be lifting the body for this so if is complicated and requires a lot of rework on that cross member I will probably keep the TH400.
- The car has the TH-400, which I know mates to an LS fairly easily. Should I do a rebuild on it, have somebody rebuild it (can you find anybody to do that nowadays) buy a rebuilt one, or consider a newer auto transmission as part of the swap?
- Rear End
- The rear end needs rebuilt, I think it is a 3.08, would not change that
- Steering
- I really like the borgeson conversion in the '73, will plan on doing that as well
- Tank
- I used the stock tank and installed an external pump and that works well, but I think for this I would buy the whole tanks setup ready to go for FI.
- Radiator
- I used the 90-02 f-body radiator in the '73 and so far it runs right where it should for temp so I would plan on the same thing.
Scott
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
- Engine
- A corvette LS1 would be ideal, use the stock accessories.
- The LS3 I got was from a 2014 Camaro and I had to swap out for the CTS-V accessories, not a big deal, but that low alternator scares me if I ever have to replace it, will probably have to lift the motor, I prefer the alternator up high like the LS1
- The LS3 is realistically more motor than I need (but fun!), an LS1 will suffice.
- A corvette LS1 would be ideal, use the stock accessories.
available.
- Transmission
- The car has the TH-400, which I know mates to an LS fairly easily. Should I do a rebuild on it, have somebody rebuild it (can you find anybody to do that nowadays) buy a rebuilt one, or consider a newer auto transmission as part of the swap?
- What is involved with a 4L60 swap? I will not be lifting the body for this so if is complicated and requires a lot of rework on that cross member I will probably keep the TH400.
- The car has the TH-400, which I know mates to an LS fairly easily. Should I do a rebuild on it, have somebody rebuild it (can you find anybody to do that nowadays) buy a rebuilt one, or consider a newer auto transmission as part of the swap?
- Tank
- I used the stock tank and installed an external pump and that works well, but I think for this I would buy the whole tanks setup ready to go for FI
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
Unless your 400 is broken just leave it be? with a 3.08 no need for OD really
Some use the truck accessory systems, alt sits up plenty high. Ac doesnt that may be an issue or not .
Doesnt Holley sell a setup?
If you stroked a 6.0 to a 408 it would pull that gear all day long
Some use the truck accessory systems, alt sits up plenty high. Ac doesnt that may be an issue or not .
Doesnt Holley sell a setup?
If you stroked a 6.0 to a 408 it would pull that gear all day long
Last edited by cv67; Sep 10, 2020 at 10:14 PM.
Melting Slicks
Joined: Apr 2001
Posts: 2,030
Likes: 363
From: Lubbock Texas
I just replaced my TH400 with a 4L60E. Fairly easy bolt in swap. Will need new cross member and new driveshaft. If you go with the electronic version, you'll need to find a place to mount the controller and run the wiring. I swapped it in by myself using my Quickjack and a Harbor Freight transmission jack. Silver Sport Transmissions sells an A41 kit that comes with everything you need for the swap including cross member, driveshaft, shifter conversion, etc. If you'd rather put the kit together yourself, Shiftworks sells some of the components you'll need.
Just went down this road and I very much prefer the OD with my 3.08s. Engine no longer turns over 3,000 RPMs at highway speed. It just cruises right along at around 2100.
DC
Thread Starter
Burning Brakes
Joined: Apr 2017
Posts: 877
Likes: 80
From: Frederick MD
I just replaced my TH400 with a 4L60E. Fairly easy bolt in swap. Will need new cross member and new driveshaft. If you go with the electronic version, you'll need to find a place to mount the controller and run the wiring. I swapped it in by myself using my Quickjack and a Harbor Freight transmission jack. Silver Sport Transmissions sells an A41 kit that comes with everything you need for the swap including cross member, driveshaft, shifter conversion, etc. If you'd rather put the kit together yourself, Shiftworks sells some of the components you'll need.
Just went down this road and I very much prefer the OD with my 3.08s. Engine no longer turns over 3,000 RPMs at highway speed. It just cruises right along at around 2100.
DC
Just went down this road and I very much prefer the OD with my 3.08s. Engine no longer turns over 3,000 RPMs at highway speed. It just cruises right along at around 2100.
DC
Thread Starter
Burning Brakes
Joined: Apr 2017
Posts: 877
Likes: 80
From: Frederick MD
I have bought stuff from Lee C Parts ( https://leecparts.com/ ) he is only about 90 minutes from me, he has a corvette LS1 and two corvette LS2s available, including one with 55k for 4.5k. The more I think about it I should probably go right to the LS3 again, it is a known quantity for me.
Scott
Scott
Thread Starter
Burning Brakes
Joined: Apr 2017
Posts: 877
Likes: 80
From: Frederick MD
I have 6.8k burning a hole in my pocket, thinking about getting this, the same thing I put in the '73 but with the automatic transmission.
https://leecparts.com/collections/ls...liftout-tested
Any idea how tough it would be to get that in? I have a request in to Silver Sport to see if they have a crossmember/driveshaft/whatever else kit for this.
Scott
https://leecparts.com/collections/ls...liftout-tested
Any idea how tough it would be to get that in? I have a request in to Silver Sport to see if they have a crossmember/driveshaft/whatever else kit for this.
Scott
Melting Slicks
Joined: Apr 2001
Posts: 2,030
Likes: 363
From: Lubbock Texas
I briefly researched the 80 series transmissions before settling on the 4L60E. Various comments on the forum said the 80 series were too big and would require hacking the tunnel. However, I found a couple of comments from guys who actually installed the 4L80E. They said it was a tight fit but no tunnel modifications were required. Not sure how the 6L80E compares in size to the 4.
DC
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Melting Slicks
Joined: Sep 2010
Posts: 3,284
Likes: 688
Another engine to consider is a L92 out a pickup. They have the good heads. Put in a small cam, better valve springs and push rods.
Add the LS3 intake and injectors. I've done a couple of these and its an easy 425 hp at the rear wheels.
I would go 4L60E and regear to 3.70's. And then since I like spending other peoples money a nice quality 2800-3000 stall converter from either Yank or Circle.
Instructor
Joined: Apr 2006
Posts: 123
Likes: 103
From: Abingdon Maryland
I did the L99 6L80 in a 73 Coupe, removed the VVT and DOD to make it an LS3. If you go this route I can send you pictures of how I modified the cross member and other things to do the swap.