K10 Suburban - 5.3 or 383 with FI?

[Tug87]

Hi All,

Hope you're having a great summer!

Long story short I'm going to be buying a bit of a beater car / truck to put some miles on in the upcoming months.

I have a 71 K10 Suburban that I normally use as a daily driver. It has a very tired 350 and th350 in it currently, as well as a 4" skyjacker lift (will be changing to ORD).

My original plan was to do a 383 with fi and a 700r4, which would make it a fine daily driver.

I'm thinking about picking up a 2003 Avalanche for sale near me with 140k on it to use for a short time then part out keeping the 5.3, trans, wiring, and fuel system.

I feel comfortable doing wither swap but I'm mostly concerned with downtime, costs, and ease of the swap while maintaining the 4wd and np205.

I've found plenty of swaps ranging in budgets, but very few with a K10 suburban. From those who have been there, which do you feel would be the better swap - taking into account downtime, cost, and ease?

Appreciate your input! Thank you!

[cj847]

My vote is LS everything especially if you are going to drive it. The SBC is obviously easier, faster. Definitely go FI.

On the downtime, pitfalls issue:
1) I am assuming the avalance is a 4wd (ie the trans is different).
2) The NP205. I haven't checked to see if there is an affordable adapter for it to the 4L60E. Check Novak and Advance Adapters. I would switch to an NP231 passenger drop (1988-1991 K5 and Suburban).
3) If I had an entire truck (as you do), you have lots of options, for example using the fuel pump out of the truck vs aftermarket.
4) Other than those LS swaps are well documented.

My reasoning - even as old as I am and my lifelong love of the SBC, there is nothing better than having a computer to keep an engine in tune and help diagnose when it's sick.

[Tug87]

Originally Posted by cj847

My vote is LS everything especially if you are going to drive it. The SBC is obviously easier, faster. Definitely go FI.

On the downtime, pitfalls issue:
1) I am assuming the avalance is a 4wd (ie the trans is different).
2) The NP205. I haven't checked to see if there is an affordable adapter for it to the 4L60E. Check Novak and Advance Adapters. I would switch to an NP231 passenger drop (1988-1991 K5 and Suburban).
3) If I had an entire truck (as you do), you have lots of options, for example using the fuel pump out of the truck vs aftermarket.
4) Other than those LS swaps are well documented.

My reasoning - even as old as I am and my lifelong love of the SBC, there is nothing better than having a computer to keep an engine in tune and help diagnose when it's sick.

Thank you for your thoughts!

1. Yes it is
2. Looks like there is and the output shaft needs to be swapped out. Some peoples swaps don't mention this so I'm unsure if it's preference. Kit is around $800
I'm familiar with Jeeps and the NP TC's - seems like the NP231 ranges from $700-1,200
3. That's what I was thinking!

[kwmech]

You do not want the 231 t-case you want the 241c. 231 will not fit the adapters or splines. AND there are 2 different ones, 1989 only has the speedo cable and 90 and 91 have the electronic speedo. 1988 was a mix of 208 and 241, but for parts purposes the 241 pass drop was made for 3 years

[cj847]

kwmech is correct. I slipped up on that one.

[52napco]

I would keep the 205...it's proven and many options for adding VSS
and retaining speedo cable.. adapters are affordable
To use the 4L60..and 5.3 is the way..most people use either
Fitech or Sniper made in China crap to add FI and it's hit or miss if you get one that works

[72-k20-burb]

Go LS.
My friends 70 with FI will never be as reliable for a daily as my 72 LS swap. The time to convert is longer, but you'll be opening the hood less later on.

Honestly his FiTech isn't that much better than my 71 with a properly tuned carb.

Keep the 205. You can find an adapter for anything. I have my original 205 on a 6l90e. You might have to change the output shaft for 4x4. I did and I took a few tries to get the right one.

[52napco]

Originally Posted by 72-k20-burb

Go LS.
My friends 70 with FI will never be as reliable for a daily as my 72 LS swap. The time to convert is longer, but you'll be opening the hood less later on.

Honestly his FiTech isn't that much better than my 71 with a properly tuned carb.

Keep the 205. You can find an adapter for anything. I have my original 205 on a 6l90e. You might have to change the output shaft for 4x4. I did and I took a few tries to get the right one.

Very good advice....100% correct

[Yerboogieman]

I refreshed the original 350 in my K10. Nothing too crazy, top end, cam, oil pump, etc. Bottom end was gone through not long ago and some junk refurb heads slapped on. Now that it breathes, I put the carb on it to get it moving, got it on the dyno and tuned it. I swapped in a 700R4 that was built to the hilt with an Advance Adapters spacer. I calculated I think 9:1 compression with the heads and pistons so it will run great on regular 87 octane. Pulls a decent combined 13mpg. I plan on doing fuel injection in the future because carbs are just a controlled fuel leak in my opinion, but for now it is very street friendly.

Advance adapters makes a ton of stuff to adapt to the NP205, like the spacer I used for my 700R4. You can remove the speedo housing from the 205, drill out the speedo cable hole, thread it, and replace the speedo gear with a reluctor ring. They make kits for that. A quick search shows OffroadDesign has a speedo housing kit that is already drilled, threaded and ready to go.

An LS is cool, but I would prefer one in a street car over a truck where weight isn't a big issue. A fully dressed 5.3 iron block is around 100lbs lighter than a fully dressed Gen1 SBC. The reason I kept the 350 in mine was it was numbers matching, 4 bolt main, and aftermarket parts and bolt ons are CHEAP. I spent around $1000 for cam, heads, roller rockers, used intake, used carb, and all the refresh parts. I'm not concerned with numbers matching, just thought it was cool.

I plan to LS swap my BMW E39 when the M54 wears out, except M54s never die.

Basically, if your 383 is already set, healthy and just needs FI and modernized parts, I'd go with that. If it's worn out and probably needs to be blueprinted, I'd swap in the 5.3. Either way, you're gonna need to do an electric fuel pump, maybe lines, and wiring.

[hevy_chevy67]

My 2 cents: go LS.

I did my first LS swap this past winter on my 2wd Suburban. If I could go back and re-do how I did my 69 C10 that's how I would have done it. I also have a Sniper EFI on the shelf for my K10 but now I'm selling that and going to LS swap it this winter as well. Going to be some extra cost to mate the 4l60e to the NP 205 and with the 4x4 front crossmember, but worth it in my opinion. The FI injection is nice, but man you can't beat the drivability and reliability of that LS. I love it in my Burb.

[kwmech]

FWIW I have a square bodied 'Burb. When I can afford it I will be building a 383 for it. I have to keep it simple as in Calif we have smog laws we have to adhere to. Going to the 383 makes the visual inspection a no brainer as...well... you can't see the inside, will look like a stock engine

[Tug87]

Coming back to this as that thing called life got in the way... Damnit!

So it's time to start piling everything together to swap out the tired 350.

I'm back to almost daily driving the 71 burb so I was thinking about staging the swap. Essentially swapping the LS in with adaptors to the Th350 then when I have more time taking care of the trans in another block of time.

I feel this would boil the engine part of the swap down to radiator, fuel lines, engine mount adaptors, trans adaptors, and wiring.

Thoughts on this approach? Thank you!

[Bigdav160]

Doesn't the LS swap into a K require a replacement crossmember?

[Tug87]

Yes I was planning on getting these DirtyDingo

[kev2809]

tbh I would do the entire swap with trans now.im not sure what wiring harness your going with, I redid the stock one that came from the Tahoe I bought..and it wasn't hard at all. I bought my 2002 Tahoe 4x4 wrecked for the same purpose, but I couldn't gut it at 125k miles so I fixed it and it's my daily now lol. luckily I found the Tahoe a year or 2 later.

nothing beats turning that key and it cranks right up even after sitting for weeks

[northburb]

Originally Posted by Tug87

Yes I was planning on getting these DirtyDingo

Wished they had this when I did my conversion years ago... I had to fab my own mounts...

[iriereggaeman]

Hey Tug87! I'm starting the same process to swap out my tired SBC350 for an LS, and came along this thread. I have '72 K10 Suburban. Any progress or photos?

I live in Central FL, and would like a knowledgeable mechanic with LS-swap experience to do mine as I simply don't want it to drag on for months, and make a bunch of 1st-timer mistakes.

Thanks,
-G

[HO455]

Have you checked out this section of the forum?

http://67-72chevytrucks.com/vboard/f...play.php?f=206

[iriereggaeman]

Thanks HO455! I have perused that section a bit. I'm hoping to find someone in the Central FL area who can do the LS swap for me...I don't quite have the mechanical chops, or time and space, to pull this off myself.

[HO455]

You might start a "Looking to Find." thread in the Pickup or the General Discussion section asking for leads to a vendor that could do the swap. Lots more eyes looking in those sections.
Good luck.