LS into a 72 GMC
 

New guy here!!

I've got two trucks, a 1970 Chevy SWB 4x4 that I jus took the factory 350 out (original engine, wrapped it up and put it in the barn) and dropped in the 383HT. This will be my driver while my 72 gets put through the process of rebuilding her.

The 72 is a SWB 4x4, one owner factory air truck that I bought and it need a lot of work. I'm going to take it down to the frame and start from the ground up. I'm thinking of putting an LS into this one and I'm either going to use the 6.0 (easier to find and) or the 6.2 (harder to find and more expensive). I can't imagine I'm the first guy to want to do this swap, I'd love to hear from someone who has done this for any potential issues I may run into. Thanks!!'
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Re: LS into a 72 GMC
 

Check out the LS swap section.

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

Re: LS into a 72 GMC
 

The amount of people that has done this (including myself) are well in the 5 digits :-). There are tons of information on the LS section of this forum. Welcome on board.

Re: LS into a 72 GMC
 

I'm working on an ly6 6.0 swap into my 72 K/20 as we speak. The info is all there. Like everything else with these trucks it just takes time and money. That's a great looking truck!

Re: LS into a 72 GMC
 

Mines at the muffler shop today getting 2-1/2" dual exhaust installed.'72 k10 with and LQ4/TH350 Done all the work myself but up here it's cheaper to get a shop to do the exhaust than order one from Summit...

Many helpful people here on this site..

Re: LS into a 72 GMC
 

I'm doing the same swap using an ls3 out of a 2015 camaro. What transmission are you going with? I'm thinking of going with a 4l80E and adapt it to the np205. Ive read some threads and most people suggest moving the crossmember forward to accommodate the extra length of the transmission. I also have a dirty dingo engine crossmember I bought a few years ago for the swap. I'm still debating on what controller to use. Holley is at the top of my list because it self tunes but is pretty expensive. Below is an excellent thread from another member.

http://67-72chevytrucks.com/vboard/s...d.php?t=421030

Re: LS into a 72 GMC
 

Pretty cool that four of us are doing the same swap. I'm using an ls6/4l80e/np205. To mate the 4l80e to the np205 I used this advanced adapters kit
http://www.advanceadapters.com/produ...h350-or-sm465/
It's a tail shaft swap. What diff gears to you plan on using? What are you other guys using? Do you plan on using lockers?
Right now I'm ready for re assembly. I'm stuck on what headers to use. Can't seem to get a definite answer of what works and what doesn't. I know trail blazer manifolds fit but would rather go with headers. Ive "heard" that Schoenfelds fit but can't confirm nor can they. They're going to ship me a set to try and pay shipping back if they don't. Suburban99 what headers are you using?

Re: LS into a 72 GMC
 

I'm thinking I'll swap out to 373s when I'm done with mine. I don't plan to wheel do nothing crazy. Did you move he engine forward? I know the Adv mount is pretty long. I think 4 inches if im not mistaken? I would look at shorty headers. They may give you more clearance. I may go with a set myself. What are your plans for wiring and accessories? I'm considering Holley for both.

Re: LS into a 72 GMC
 

I am using stock 2500HD manifolds...needed to trim the frame ever so slightly. The exhaust I had made has a couple of incredible bends in it. The guy was a real artist...(and charged like it)..but I am happy with the result. The truck is amazing to drive now that I sorted out my VSS issues..this is the second LS swap I have done ( Sold the first one to pay for the second one). I have done all the work myself except the exhaust.

Re: LS into a 72 GMC
 

I would recommend moving the engine forward as it's very tight in the stock position. I read somewhere the K's engine was further back from the factory...(I could hardly get the HEi distributor cap off mine with the 350 in it)...I needed to adjust my firewall to keep the LS in stock engine position.

Re: LS into a 72 GMC
 

Blazerowner...unless your wanting a lower gear you may want to keep those 3.73s..with your 4l80 od and a decent tire you may needem to keep your cruise rpm range good..I kept my 4.10s w/od and wouldn't even consider changing to higher gears..use one of the rpm calculators to figure your cruise rpm..here's one of many that are online...
http://spicerparts.com/calculators/e...rpm-calculator

Re: LS into a 72 GMC
 

I would swap to 373s as I'm pretty sure it has 307s. That will be last as everything else is so expensive. The ls3 cost me 5k and that was a deal with what I got with it. Only has 2400 miles on it. I'm still debating what to use to run it. I was thinking one of the gm kits but I don't like the fact I would have to take it to a tuner ever time I make changes. What I want though is it to fire up like a new car. No waiting for a fuel pump or anything else. Just turn the key and drive. Is this feasible or am I being optimistic?

Re: LS into a 72 GMC
 

I'm going to run 4.10s or 4.56s. RPMs with the 4.56 in OD is still good. I haven't mocked up engine location yet but figure my set up is around 4 to 5" longer than the 350/th350/205 original set up. Im planning on moving the engine forward half the distance and rear cross member back the same. I already planned on new drive shafts. Probably gonna have to extend the 205 shift linkage a bit.
As for accessories, I bought an entire bolt on set up that was designed for these trucks. I don't remember the companies name. It's all still in the box. They had a booth at the turkey run in Daytona. I really liked the way it looked. I'm gonna install it in about two weeks.
As for ECM, trans controller and harness, I'm still debating that one. I'm half way considering this self learning set up so I can also avoid the whole modification/tuner thing. Thinking about this:
http://fitechefi.com/products/ultima...ction-systems/

Re: LS into a 72 GMC
 

Blazerowner...Mine will crank in under 2 seconds from key turn...

Re: LS into a 72 GMC
 

Nice that's what I want, turn the key and run. The reason I want to move the engine forward is I don't want to modify the drive lines nor the location of the 205 shifter. In the link I attached above I believe he used a stock 4l80e 4wd adapter which he mentions is shorter than the advance adapter setup. The Lomax case bolts directly to it which I thought was pretty nice. The Case isn't cheap though which I'm debating as my 205 is fairly fresh. As far as the Fitech, I already have an intake and throttle body and I don't believe their ECU controls DBW. They do have a kit that is just wiring for about 1k with trans control. Its not killing it for me considering the price of the holley terminator kit, but I would like to have DBW and don't want to buy another throttle body. I also haven't been able to find real world feedback on their products. Is it made in the USA? the intake looks a lot like overseas intakes I've seen on ebay.
Attached a pic of the LS3.

Re: LS into a 72 GMC
 

I didn't know about that Lo Max np205 upgrade kit with the adapter. Pretty cool but way to late for me. I've already got the advanced adapters tail shaft and housing on the back of the 4L80e. I would have definitely considered it if I had known about it. I'll know more when I mock it all up. I don't think moding the 205 shifter will be a problem.
As for the Fitech product, I think that intake and other hardware is made in china. I've seen what appears to be the same intake all over the internet lately with different company names on it but its place of origin is china. And it IS only DBC and not wire. I'm about a month out from needing my electrical components so Im going to sit back and watch because I have heard zero feedback as well. The only other "self learning " set ups that I know of are the Holley that you mentioned and I just learned that FAST has one as well. Both are pricey but have good reputations and tech support. Im definitely going self learn ecm because I think it will do what I need it to. Its a big heavy 4x4. Im not trying to shave hundredths off an 1/8 mile track time.
Nice looking motor!

Re: LS into a 72 GMC
 

I'm not worried about shaving track time either, more so drive-ability. Any idea what the length is on the stock th350 to np205 adapter compared to the adv adapter you used? Seems like it would be the same. I'm looking for a 4l80e used that's in good shape. Did you go with a 4wd version? The lomax is $2800 assembled, ouch. I don't wheel nearly enough to justify the cost. The kit might be the best way to go for the money.

Re: LS into a 72 GMC
 

Wow! I didn't know it was that expensive. Glad I went the route I did. Can't remember on the length of the stock adapter between the th350 and the np205. I wanna say it was the same. With that advanced adapters kit you'd want a 2wd 4l80e. Preferably 94 or newer. If you got an older one you'd have to switch out the internal wiring harness. Not a big deal really.
Here's what their site says:
Quote: "Transfer Case

The adapter assembly fits 1971-79 GM NP205 with a figure 8 front bolt pattern, and is designed to replace the 10 or 27 spline male inputs. If the GM NP205 is equipped with a 32 spline female input, the new 32 spline input that is included in the kit will not be needed. Call our tech line for more info.

Transmission

The adapter kit is designed for exclusive use with the GM 2WD 4L80E. The 2WD 4L80E must have a 6-1/2” slip yoke output shaft. A GM 2WD 4L80E output shaft speed sensor must be used"

Re: LS into a 72 GMC
 

Yeah they are pretty pricey. I'm considering the adapter more so. There's this option as well.
http://offroaddesign.com/catalog/Tra...seAdapters.htm

Re: LS into a 72 GMC
 

Well now, that looks just too cheap and easy to not do it. It would be nice if they had installation instructions on their website so you could see exactly what you were getting into. Sounds like you could use the 2wd or 4wd 4l80 if im reading it right.

Re: LS into a 72 GMC
 

I was thinking it did look viable but the issue may be the input on the 205. The Adv adapters comes with this. Did you have to change yours out? Mine is the orig np205 that was behind the th350 and I assume it probably isn't the 32 tooth input. I would like to see some instructions as well, I may have to call them and see what they say.

Re: LS into a 72 GMC
 

Yes the input on the 205 was changed out. I had a local trans shop rebuild the 205 and install the input. It was way above my skill level to do it. It required machining for the larger bearing of the 32 spline input. Here is a link to the advanced adapters instructions.
http://www.advanceadapters.com/downloads/500410.pdf
Its good info and should help understanding exactly what's required.
It doesn't appear that the other kit comes with the input. Could be the reason for the huge price difference.

Re: LS into a 72 GMC
 

I'll have to call and see what they say about the input. Seems like it would need to be changed out.

Re: LS into a 72 GMC
 

It is cool that there are several of us doing a similar swap. For me I'm going run a 6l90 with my 205 with the aa kit. I plan to keep my 4:11s and run 33s. That ls3 looks really nice. I'm going to run the ls3 intake on my ly6. Im planning to leave the 205 in the stock location as well so I don't have to mess with drive shaft mods.

Re: LS into a 72 GMC
 

When are you doing the 6 speed swap?