My 1980 Sierra LWB build

[C15_Sierra]

Hi, I'm new to the forums and this'll be my thread to document my build. I bought my 1980 GMC Sierra C15 LWB for $900 last month, and my plan is to restore mostly to factory-spec with a few little tweaks. For $900, I got a running truck with a good but tired motor and nice running tranny (useful for moving it around), and it passed inspection last week with flying colors.

The history behind the truck, that I know of is as follows: I know of 2 previous owners, the guy I bought it from purchased it in 1988. It's been in Killeen, TX most of its life, and it shows - all the metal is solid. It was driven by an old man, and had done less than 50K in 23 years. There are a few dents here and there, but nothing I can take care of. It was originally a 6-cylinder/3 speed manual truck that was converted to a 305/TH350 from a '79 Camaro back in the '80s. Still has manual brakes. Truck has 193K on it, but the engine only has 93K on it and hasn't been rebuilt. Transmission might have at some point, it looks newer than the engine Runs like a tired 305, but it starts even after sitting so its good enough to use in a pinch, and the tranny shifts smooth.

The Vision: Not a drag/sport truck, but something that has a little power off the line. Not a work truck, but something that can tow or haul a load every once in a while. Not a restoration, but looks clean inside and out. Streetable factor is high

Plan:

EXTERIOR
-Remove camper top (DONE)
-Knock out/fill in dents
-Respray exterior to factory color (Dark Carmine Red)
-Add chrome front bumper OR paint-match and respray front bumper
-Rear roll pan and add hitch
-Replace windshield
-Replace weatherstripping (DONE)
-Replace right vent window (glass was busted; DONE)
-Replace/repair binding door hinges (DONE - shot with PB blaster, freed up pass. door and drivers door is now 90% free)

INTERIOR
-Re-upholster stock bench w/ Red Cloth (have upholstery and spare '80 K10 bench)
-New dash cap (DONE)
-Found a urethane GMC steering wheel from a newer pickup (OBS maybe), might see how it looks once the interior shapes up
-New carpet/sound deadening
-New audio system - radio, 4 cab speakers - might refurb old radio to include an AUX jack
-New door panels (Not installed yet)
-Sunpro Tachometer (DONE)

CHASSIS/SUSPENSION
-Spray with rust converter/paint chassis black (Part Done)
-Urethane control arm/leaf spring/cab mount bushings (Part installed)
-Shocks work good for now, but repaint for now
-New 5-lug rallys, have original '84 GMC metal center caps
-255/60-15 tires

ENGINE/TRANSMISSION
-Yank the 305 out (DONE)
-Install 5.3 Vortec with 4L60E (DONE)
-3.73 Posi Rear (original = 2.73 non-posi) - not sure if I'm rebuilding my original 12-bolt or trying to source a 5-lug 3.73 posi

Pics from when I first bought it













My boss from work is helping me out with this truck (I'm doing all the work at his shop) and as soon as he's done painting his '84 GMC, mine will be next. Until then I'm going through the truck and determining what I'll need to buy/fix so that I'm not stuck waiting around for parts. I've got my work cut out for me, but I have some fab skills and am able to quickly pick up what I don't have previous experience in.

Any comments/suggestions/feedback would be appreciated. I'll also be using this thread to bounce ideas/questions off you guys to get opinions/answers about the truck. Thanks for reading!

[C15_Sierra]

As of 4/10:

-I've cleaned up the interior and taken the dash apart
-I sprayed the cluster housing with chrome touch up. Don't know the effectiveness yet as I've been mostly working on the truck in the daytime. I also replaced the speedometer and fuel gauge as I broke the needles on both of them while taking out the cluster (they were really brittle). My friend has the cluster from his '84 GMC that he's not using but can't find it (DOH!) - when he does that might go in because my small gauges are all busted (again, brittle needles/careless handling).
-Took out the stock rubber flooring and old sound dampening.
-Removed the bumpers and hubcaps. New tires on the rallys hopefully by next week

Question:
-Does anyone make the seal between the vent window frame/glass. LMC has it diagrammed but theres not part # associated with it. Thanks

[C15_Sierra]

I need some opinions on my motor swap. I want to get rid of the 305 and put something in that has power, reliability, and a good sound. Since I'm emissions-exempt, anything goes. I want to run full-length headers, and a true dual exhaust, dumping just after rear wheels.

The two options I'm considering:

Built 350 or 383: I want to run a fuel injection setup on this motor, so I'd prefer to swap in a Vortec 350/383. My boss runs a 383 w/ Vortec heads in his 1970 C10 and I love everything about that motor: the sound, power, and since it has a TBI setup, it starts up and runs great. The cost would be greater to swap and build just the motor than a stock LS swap (see below), but I wouldn't run into the exhaust and AC compressor clearance issues that seem to plague most LS swaps. Plus its the classic SBC, and that should count for something, right? I could use my TH350 for the time being, and swap to a 700R4 at a later date (friend of a friend owns a transmission shop and can hook me up)

Vortec 5.3/4L60E: I priced out a 5.3/4L60E from LKQ at $1400, and will see if I can get a little lower than that. Looks promising with 300 hp out of the gate, but I'd have to reprogram the computer (not a big deal), buy new motor mounts (again no biggie), and fab a new transmission crossmember. The biggest worries are the AC compressor and exhaust clearances, since my friend is running into those issues on his '84 GMC LS1 swap. I'd like to keep my factory AC so there would be some conversion issues with the LS swap that I wouldn't run into with a SBC swap. I also don't like that I'd have to run a electric-to-mechanical speedo conversion box to keep my mechanical speedo, but hey theres no free lunch . I do like that its a modern drivetrain in a classic wrapper, and again since I'm looking for high streetability, that works well w/ my vision. Theres an '04 Silverado at work with over 230K that runs well and gets over 20 MPG on the highway, so I know my money would be well spent with an LS swap.

What do you guys think/do you have any insight into how I should approach my decision?

[C15_Sierra]

Thought it over and decided not to settle on a 350 and that a 383 would be a PITA to build right. My boss' 1970 C10 has $8k in motor work alone and I dont have the time or cash to really do it right. I want fuel injection, so a 5.3/4L60E is really a no brainer for my power and driveability requirements. The search is on for a 5.3/4L60E combo, which shouldn't be that hard to find. Any recommendations on motor mounts/placement? Ideally I would like to run full-length headers but am aware of potential clearance issues. Also, is there a motor placement where the A/C compressor has clearance in the stock location? I know there are relocation brackets available, but am looking at other options

Sorry for the severe lack of pics, it got dark as we were taking the bed off, and was too dark for my camera phone. Will take some today though

[C15_Sierra]

She's looking more like a project truck these days. I took off the bed and powerwashed the rear of the frame. Underneath the dirt revealed a clean 31-year-old chassis with no rust. Typical for a Texas truck I guess, but I'm a CT native so seeing a chassis that looks this clean after 31 years (and 193K miles) is an awesome sight!

[Pop's C-10]

nice plans

[bharrison1]

Cool project!!

[Gordonr1973]

Look here for all the swap information:

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

And look here for examples of other builds:

http://67-72chevytrucks.com/vboard/s...d.php?t=457939

Read up on these and you should be able to start planning which way you might like to go...good luck! :-)

[C15_Sierra]

Thanks Gordon! I've actually gone thru a lot of these threads (lurked for a little bit before getting the truck and right after) and decided to go with my original plan of an LS swap (was tempted to build up a classic SBC but ultimately decided against). I feel pretty capable of making everything work, and I think I've got a good list of what needs to get done!

In other news, I painted the rear part of the frame in Eastwood Satin Chassis Black. Turned out nice. My bushings came yesterday so I'll probably tackle the rear leaf and shackle bushings next before putting the bed back on. While I had the bed off, I tested its burnout capability - passed. Thought maybe I had a half shot of having a posi, I don't. I also checked out the gearing...2.73! So the gears had to have been changed out at some point. And no wonder I couldn't spin the tires with the bed on! Maybe my 305 isn't as tired as I thought it was, but at least it'll settle down and cruise on the highway even with the TH350. Not that I'm planning on keeping it around much longer haha...anyway, pics for now...

[C15_Sierra]

I used this weekend to start prepping for the motor swap as my plans have changed a little.

Since my last update, I've been busy:
-Ordered Swaptech adjustable motor plate adapters
-Disassembled the front end - radiator/condenser, front grill, what was left of my battery tray (and added the need for a new RF inner fender), etc.
-Drained all the fluids. Didn't even take it for one last run, I won't miss this motor
-Disconnected the driveshaft
-Undid the exhaust, transmission mounts, what little wiring there was to the engine
-Put a deposit down on my 5.3 and 4L60E. I will be pulling the wiring harness from the truck (an '00 Silverado) before the yard pulls the motor out in the next couple days

Here she is, getting ready to say goodbye to the 305...

[Pop's C-10]

That frame looks good

[C15_Sierra]

Thanks Pop.

Got the motor and transmission out tonight. Didn't get pics because it was so dark by the time everything came out. Picking up the new engine and transmission tomorrow. Motor plate adapters are on their way, should be here on Thursday. If everything goes well I should have the motor and trans installed so that I can start wiring and measuring the driveshaft. Movin' right along!

[C15_Sierra]

Finally picked up my 5.3 and 4L60E today Touched up the frame and engine bay the other day. Now I'm getting started on prepping the motor to get bolted to the frame and sort out clearance issues and get measurements for my driveshaft. Look for some questions as I'm new to LS motors

Look ma, no engine!


Goodbye, 305!


Old and busted


New hotness




4L60E transmission

[lucjensen38]

Actually 2.73 gears are common in 1/2 tons. My 1978 GMC sierra c15 has that gear set. But it also had a 350/th350 with air and power windows. Top-o-line back then. I dropped a 700R4 from an 86 burban and a 292 from a 1980 GMC c25 camper special. It goes like hell. I can burn the tires either but compared to the th400 and 4.10s in that 80 ill take the 2.73's. My truck someday will be kinda like what your doing to yours, no show chrome valve covers or mirror paint, but super clean streeter that everyone will notice just for the looks alone. It would be an injustice to make mine a show queen, its spent the last. 32 years as a farm truck hauling the diesel tank to fill the tractors and hauling grain carts to town and feed to the animals and seed to the planter. Almost everything works, save for the gas gauge. The + wire is on the tank but broke off at the cab somewhere and I can't find it yet. Anyone know where I could look for that?
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[C15_Sierra]

Wow, lots to update in this thread, kinda got off track a little bit from the first few months (spent almost every day on this truck after I bought it) because life got in the way a little

Since the last update, I've switched locales - I made the x-country trek from Texas back to my native Connecticut, I took a new job with a new company as an engineer (was a management trainee before at my old job). Brought the truck with me (which is an interesting story in and of itself, but this is a build thread). It sat for almost 2 months at my parents' place (no garage space for it there) which is about 75 miles from where I was living, so not much work got done. After buying a house (now I'm REALLY broke) I moved it up into my tiny garage - I've got about 1-2" clearance in the back and 3-4" clearance up front - it's a tight fit!

No pics right now - I haven't been documenting very well lol...plus Photobucket is disabled at work, so no uploading until I get home - but here's what I've accomplished in the last month or so:

-Bought a set of long-tube Schoenfeld headers from Summit Racing that clear the frame. They're intended for 88-98 LS swap trucks, but seem to fit 73-87's fine as well. I had to remove the AC box and in the process, I broke that (oops!). On the first trial it fit, but I will re-fit once I fix some tranny issues (see below) and mount the starter.

-Bought a new '87 LWB tank ($100 shipped from 1A Auto, which is close by in MA so it arrived next day ), which I painted with Eastwood tank-tone paint. Bought new straps from 1A as well and painted those with the same paint to keep them from rusting. Repainted my original tank brackets with Eastwood chassis black

-Bought a new '87 sender from RockAuto, along with an ACDelco EP241 (Corvette/F-body pump) from eBay

-Finished painting the frame (or what I could reach w/ the cab still on)

-Separated the '00 Silverado wiring harness from the motor - de-loomed and cleaned it, and it's now sitting in my basement with Alldata pinouts (thanks to a tech at work who used to work at a dealership) anxiously awaiting a meeting with my dykes

-In the process of dropping my transmission...when I installed it on the motor I didn't check to see if the converter was properly seated (it came from the yard with the converter already installed) - newbie mistake - and as a result I have no clearance btwn it and the flexplate. Didn't find this out until I had to install the torque converter bolts. Oh well. Once I get the tranny dropped, I will inspect/repair if necessary and clean it (still has some OEM dirt lol)

Next steps to be completed in the near future:

-Complete the header fit, strip them of the cheap shipping paint and paint with VHT

-Complete the fuel system - I plan on running 3/8" Summit Racing fuel injection hose w/ their push lock AN fittings. Already bought Russell fuel rail adapters with AN fittings

-Re-flash the computer to delete emissions/anti-theft

**After Transmission is re-installed**

-Install transmission cooler lines - not sure yet if I want to re-use the stock quick-disconnects or convert to threaded fittings

-Shorten the driveshaft

-Install B&M Truck MegaShifter

-Install the headers/exhaust (going with Flowmaster 40-series mufflers, H-pipe, 2.5" true duals with either a before-axle dump, or a '67 Camaro-style fender peek behind the rear wheels



Still a lot more to do until I'm completely satisfied, but the goal for right now is just to get 'er running so I can at least move it in and out of the garage. This thread is worthless without pics, so I'll try to get some up later today or tomorrow

[83 Silverado]

Cool build, I'm doing a 4.8/4l60e swap in my 83, can you post up some pic's of how the headers fit.

[foamypirate]

Awesome build! Sounds a lot like what I am doing with my truck right now...except you are making faster progress than I am, haha.

Looking forward to seeing this when it's complete, should be good!

[C15_Sierra]

Originally Posted by 83 Silverado

Cool build, I'm doing a 4.8/4l60e swap in my 83, can you post up some pic's of how the headers fit.

I only test fitted the headers to check frame clearance and I didn't have the starter mounted - I was checking to see if they would clear so that I would gauge if it was worth putting the time into prepping/painting them. I had to remove my evaporator box to get the pass. side to go in. But it should fit - dunno if they changed the engine bay configuration for the '83.

With Summit they have a pretty good return policy (in case they didn't fit), and I didn't find any other affordable long tubes for LS swap trucks, so I took a gamble. Once I get past this tranny issue and bolt it back up along with the starter, I'll do another test fit before I go to town on stripping/painting them.

I'll be sure to get pics when I do the test fit - like I said I haven't been documenting well, and would like to change that.

Originally Posted by foamypirate

Awesome build! Sounds a lot like what I am doing with my truck right now...except you are making faster progress than I am, haha.

Looking forward to seeing this when it's complete, should be good!

Thanks, like I said before I had the truck cleaned, partially painted, and motor swapped in about a couple months time, and then stopped for a while because of my job/living situation. But during that time, I had to drive from my job in Austin, up to my friend's house in Liberty Hill, and then back to my place in South Austin every day that I worked on it (during the week that is), so there was a substantial time investment that I needed to take a break from.

But I'm getting back to it, and I'm motivated to at least get the engine running in the next month before it gets unbearably cold in my garage (and mice, etc. are more enticed to make their homes in the truck). Curious to see what other snags arise when I actually get the parts turning

Good luck on your build!

[C15_Sierra]

This week's been "wiring" week at my house - wiring money and wiring the truck. I spent a good chunk of change on some exhaust parts (ball flanges for the collector and 2.5" Flowmaster 40s), interior parts (new dash pad, upholstery), and other miscellaneous parts.

At the same time I found a guy parting out an '80 K10, so I snagged a power brake booster, a pretty mint seat, dash panel, ront reflectors, and a floor-shift column with keys in great condition (truck sat for 15 years). Funny thing is, all of these parts differ in the parts they are replacing...my truck is a factory A/C truck, the bezel I bought is for a non-AC truck (but I can fix that)...the seat I bought is non-folding (mine is folding, might be possible to swap foam)...power booster is going in place of manual M/C...the reflectors are chrome rimmed (that's the reason I bought them) and the ones on my truck are just plain. So I have some mix-n-match'n to do!

I'll take a break from wiring this afternoon to mock up my headers and collector flanges to see if I can weld them together off the truck, I'm heading up north for the weekend so I would like to bring them with to weld (I have access to a welder up there) if I can fit them on later! I'll also be getting my PCM back early next week, so I should have the harness ready to be installed next week as well. While daunting, taking apart the harness has actually been pretty fun so far!

And of course, this thread is worthless without pics


K10 bench seat


K10 dash bezel


K10 Chrome reflectors


K10 Floor-shift column


Harness rewiring


Workbench #2


Just "some" of my parts stash

[C15_Sierra]

I'm making some headway on my wiring...I got all the necessary pins out of the ECM harness, as well as the fuse box, in order to wire up the engine for standalone operation - I wanted to keep the engine function separate from the rest of the truck. Had all the info I needed thanks to LT1Swap.com and I even had Brendan (the site owner) flash the PCM for me (on its way!). Once that arrives I'll install the harness and re-loom it.

I have a friend coming this week to help me drop the tranny (finally) so that we can re-seat the torque converter and re-install.

I've also been going crazy trying to find an electric speedo cluster from a 90-91 Burb/Blazer - I figured my speedo-only approach wasn't the best since my original cluster isn't in the best shape to begin with, and with a Burb cluster, I not only have the correct wiring, etc. that I've been seeking for some time, but I also have the MIL indicator that I thought would be a neat touch (a CEL in a 1980?? lol )

I had fun opening all my boxes of parts that came in at the end of last week (Christmas come early??) but sadly I lost my camera so I don't have pics. Only disappointment is that I ordered red door panels and got RED door panels lol...Fire Engine Red not Carmine Red. Maybe the Burgundy ones were a closer match, I don't know, I'll have to install them to see how they go with the interior.

I may get a header fit in this week too with the ball flanges (ran out of time last week before I went north for the weekend) so stay tuned....

[C15_Sierra]

10/25 Update -

Been busy, getting wiring loomed and installed. Haven't decided on a final mounting scheme for the ECU/fuse box - anyone have any ideas.

Pulled the transmission last week, then got swamped at work and went away for the weekend...thus, I didn't get to pulling the pan and the pump until last night. Those of you who don't know...back when I installed the transmission (in Texas!) I didn't seat the torque converter all the way, which broke the pump when I bolted it to the bellhousing. Figures that I finally get to it when I don't have a resident transmission expert at my fingertips (well, he helped me diagnose it over the phone lol, but can't fix it for me). Oh well, you live and you learn. So once I get the pump rebuilt, I will change the filter and reinstall. Not a big deal when your project has slowed to a crawl like mine...

I think I finally have all the parts assembled for the fuel system (will know this afternoon whether I ordered the right fittings for the fuel filter) so I can start work on mounting the tank and getting lines run

On the exhaust front, I am more and more doubtful that I can weld up the flanges off the truck. I may just install the headers and get the exhaust welded up when it's on the truck. The Schoenfeld 88-98 LS swap headers I bought are a tight fit - the motor is tilted back right now because of transmission work and the driver side header is interfering the control arm bolt. When I test fit them a couple months ago, they seemed to fit (didn't bolt them up) so I am confident that once tilted up, I'll have enough clearance.

Found a 91 Suburban cluster 2 weeks ago, and re-pinned my instrument cluster harness to match. Got some extra switched ignition and constant 12v wires (harness was pinned for a clock) so I can wire up an extra accessory port

Here's my running checklist:

-Finish wiring - MAF sensor/connector, O2 sensors/connectors, SBC sender adapters (not required, but nice when the engine's dry)

-Install intake/MAF, mount ECU/fuse box

-Cooling system - steam vent tube, install radiator, cooling/heating lines

-Transmission - Rebuild pump, install transmission/crossmember, run cooler lines, shorten driveshaft, install shifter

-Exhaust - install headers, flanges, get a shop to weld up some 2.5" piping and install Flowmaster 40 series mufflers

-Fuel - install tank, filter, run lines

Hopefully this won't be another 60 hr week at work, and I'm not going anywhere this weekend so I will be able to knock a chunk of this out. Stay tuned!

[C15_Sierra]

I owe this thread some pics...

Roll back to July...this is what it looked like the morning after it arrived at its new home...


As it sits now...






Looking back, it's taken me 7 months so far. Granted, a lot has happened (new job, house, 2000 mile move, hurricane, winter storm)

My buddy back in Texas has been talking smack about how I haven't gotten it running in 7 months...now that he's swapping an LS327 into a Cressida he just bought, I wanna get my engine at least running before he fires up that Cressida for the first time. Not a tall order, but would be embarassing if I didn't. So now I'm lighting a fire under my behind to get cranking before the winter months slow me down.

This past week, I pulled the steering column to swap in the floor shift column - found that the intermediate shaft from the column-shift column was splined, the floor shift column was notched. Swapped intermediate shafts with a K20 that I helped pull the motor on.


I also started work on the fuel system. I used an ACDelco GF652 filter (OEM for a '00 Silverado). I had ordered Russell fuel line and fittings, but couldn't get them to work (would get the fittings only about 2/3 way on, even with the fitting press I use at work for this type application), so I ordered some Jegs Pushloc (supposed to be easier to work with)...will be here next week

[C15_Sierra]

More assorted pics...

Column that came out of the truck


Column that's going in (from 1980 K10)


Rally's waiting on tires and some Eastwood Argent Silver paint (along w/ one of the old fuel lines I pulled)


Matching rally spare, got it from a friend


My 4L60E's bellhousing and converter. Getting the tranny back w/ new pump from a guy at work (does work on the side, expert in GM trannies)


'91 Burb cluster going in, 184k miles, only 9k off from the truck (has 193k)


New side markers with chrome trim - small detail but I like them much better, and they match the tails that are on it.


B&M shifter that's going in, and the eBay intake


Broken 4L60E pump pieces

[C15_Sierra]

'86 K20 that I pulled parts from


Motor that I helped pull...350 4bbl, looked to be a TH350C (had square pan, electrical connections)...odd in a 3/4 ton

[C15_Sierra]

B&M shifter mounted in the cab, along with my floor shift steering column


eBay intake assembled