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Discussion Starter #1
I've posted before about repairing/replacing the trans in my 85 Conquista, and how I decided to go ahead and do the engine as well.

After looking at various options including some version of a crate engine and other used engines available to me, I think I have another possibility, and it's sitting under the carport to my barn.

It's a 2000 Sierra with 150K on the clock, I bought it new and it was my daily driver until a few months ago when I got a new vehicle. Has a 5.3L FI engine, 3 speed OD AT. Runs well now, but if/when I do the transplant I would rebuild both.

Additionally, it also has ABS, bucket seats, power windows/locks/seats/mirro rs, etc., all of which I (eventually) wished to have in the Conquista.

The first questions I have are:

1. Does this sound like a good donor drivetrain? Any glaring downside?

2. What would be the average cost of rebuilding the engine and trans?

3. Is it not too much of a chore to make the power accessories work in the Conquista? I probably wouldn't be doing the work myself, so would a seasoned builder have no real hurdles with the swap?

I'm sure I'll think of a lot more questions, but this is where I'll start.

Many thanks for any input.
 

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The 5.3 is a good swap, but not without it's issues. You'll need special motor mounts and headers( F-body LS1 stock manifolds will work). Hood clearance is an issue, but can be solved (New accessory mounts; or cut the hood supports; or cowl hood; or you can also convert the intake to an LS-1 type intake, but this approach is expensive). . You'll need electric fuel pump and electric fan. All the 5.3 accessories can be used. You'll need to have AC hoses made to fit. Driveshaft length will likely need adjustment. You may be able to make the donor engine harness work, but be prepared to have it modified, or buy a replacement that will fit the Elky ($$). Speedo adapter, trans cross member also come to mind. When I was going through my planning, I think I budgeted $2000 for parts, not counting the engine and trans. And that was with me doing the work.

If you need to have the 5.3 rebuilt, and add in all the new unique items you will need, you will likely have much more invested than if you just dropped in a 350 crate motor. On the flip side, the 5.3 will give good HP ( cam change for even more power when you get it rebuilt), and will probably give a little better gas mileage due to the FI. You will also have a conversation starter!

There are build threads all over the net for this swap. Here's a couple of links for your review;

http://www.chevytalk.org/fusionbb/showtopic.php?tid/193929/pid//cto_session_id/19f5502e432fb58ae670ebb4601b91e6/

http://www.montecarloss.com/community/ubbthreads.php?ubb=showflat&Number=823398&page=1
 

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Now, I have a question about the 5.3. Why are the motor mounts different than a 5? The 5.3 SHOULD be just a different internal system to decrease the CI. The basic block should be about the same. :dontknow:

The SIERRA transmission SHOULD be a 4L60E, and very close to the size of a 700r4. But then, you don't have a 700 installed. If I remember correctly a 200 4r. Most people would stick with the 200. Also, I don't see why taking the intake/FI from the 5.3 wouldn't work on a 350. The FI should be a TPI system, as that's what I had on a '99 Silverado 5.3. Doing the plumbing/installing of the ABS is most likely going to be very daunting. There doesn't appear to be the room under the Elky that the Sierra has. There are two units to the ABS, and, iffin' I wuz you, I'd get the control unit reworked prior to installing on the Elky. I did on the Silverado when the control flopped. About $150 or so with ALL new important items replaced that are much better than GM's.
 

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Now, I have a question about the 5.3. Why are the motor mounts different than a 5? The 5.3 SHOULD be just a different internal system to decrease the CI. The basic block should be about the same. :dontknow:

GM changed the location of the mounting on the LS series engines. Many companies make an adapter to make them work in older applications.

Also, I don't see why taking the intake/FI from the 5.3 wouldn't work on a 350. The FI should be a TPI system, as that's what I had on a '99 Silverado 5.3.
The heads have a different intake shape, and the bolt holes are a different pattern. Also, the newer engines use a reluctor wheel to fire the plugs / injectors instead of a distributor.
Also, I forgot to mention that the oil pan needs to be changed as well ( 5.3 pan will not clear the cross member). Many folks use a Caddy CTS-V pan. Again, the folks that make the swap parts will have the pans as well
 

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Lucky, if you check back in the ls section, I,ve listed links & books & general advice in several spots on others threads. Ls1tech .com is a great site to search, there are g-body specific threads in the hybrids section. The 5.3 truck engine is the cheapest attainable of the worthy ls series.
You could rebuild what you already own, but if the truck is in decent sellable condition, I think you might be money ahead to sell the truck & source a later model drivetrain from a wrecked vehicle with lower miles. Just something to think about here. If you were rebuilding your own engine to something non stock & installing yourself, I might not have said that, but part of the beauty of a late model swap is to not have to rebuild it & make it fit.
As far as an abs swap, that is NOT for the faint of heart. I,d advise to spend the money on g-body aftermarket upgrades.
 

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Discussion Starter #6
Thanks darbysan, that's some really deep info, most of it lost on me right now but I'll read and reread it again and again, maybe enough of it will sink in. I know next to nothing about engines, so I don't know what an LS1 engine is or what it was originally built for. Thanks again.
 

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Discussion Starter #7
Lucky, if you check back in the ls section, I,ve listed links & books & general advice in several spots on others threads. Ls1tech .com is a great site to search, there are g-body specific threads in the hybrids section. The 5.3 truck engine is the cheapest attainable of the worthy ls series.
You could rebuild what you already own, but if the truck is in decent sellable condition, I think you might be money ahead to sell the truck & source a later model drivetrain from a wrecked vehicle with lower miles. Just something to think about here. If you were rebuilding your own engine to something non stock & installing yourself, I might not have said that, but part of the beauty of a late model swap is to not have to rebuild it & make it fit.
As far as an abs swap, that is NOT for the faint of heart. I,d advise to spend the money on g-body aftermarket upgrades.
Thanks jlcustomz, that engine info filled in a few gaps. from what little I've seen of it, the LS1tech site has a wealth of knowledge, I look forward to searching it in depth.

The truck is in great shape, I've maintained it well, very decent ride. I was actually considering letting my brother have it, he is always in need of a good pick up in his line of work. So that's still on the table if I don't use the engine/trans.

The ABS is not a must-do but would have been nice; if it's a PITA I'll drop that off the list.

Thanks again, please post any other thoughts if they come to mind.
 
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