66 GMC Long to Short LS Swap

[LostMy65]

Originally Posted by Duncan K

]

Drilled out all the spot welds and removed the dash from my chevy donor cab to swap into my GMC. Also cut out the area above the windshield to be used as a patch panel for my cab.

[IMG][IMG][IMG]

All this rust repair is starting to get discouraging so I am going to take a break from it for a while and work on some mechanical stuff. Going to rebuild the rear end with a posi carrier, new ring and pinion, and all new bearings. Adding a rear disk brake kit from CPP.

Do you prefer the look of the chevy dash over the gmc?
.
I feel you on getting burned out on certain tasks. You're doing beautiful work.

[Duncan K]

Originally Posted by LostMy65

Do you prefer the look of the chevy dash over the gmc?
.
I feel you on getting burned out on certain tasks. You're doing beautiful work.

More so the Chevy gauges, but this was the easiest way to make the swap

[Duncan K]

Moving along with the rear end rebuild. Made myself a drift out of some parts that were laying around, knocked out the old axle bearings and replaced them.



Installed a rear disk brake kit from CPP. Everything fit pretty well except the brake pads on one side. They are too thick to fit over the rotor, will have to machine off a bit of the pad to fit.



New pinion gear installed, had to fab up a tool to hold the yoke so i could torque the nut.



Got the new posi carrier and 3:73 gears installed and set the back lash



Got the driveline angles sorted out. Needed to raise the trans up an inch and a half to match the pinion angle at 5 degrees. Had a new one piece drive shaft built, had to modify the cross member to provide clearance. Still have to finish welding it up



Waiting on a radiator that I ordered months ago from RnD. Took 6 weeks to ship, and now UPS has lost it.

[The Rocknrod]

That's some great work your doing, you got talent.

[Notch1988]

Sorry about the rad. Why so long for RnD to ship?

[Duncan K]

Originally Posted by Notch1988

Sorry about the rad. Why so long for RnD to ship?

Busy I guess, was told it would be around 3 weeks, ended up being 6. Who knows how long it will be now?

[88Stanger]

Love the build! I am starting my "66 build this weekend. I just completed my full rebuild LS motor "69 C10, now "66 with 383 stroker and M20 4-Speed. Thanks for all the updates! I appreciate your work and helps me with mine.

[Duncan K]

Not a whole lot of progress in the last few months. I finished welding up the hoop over the drive shaft. Also chopped an inch and a half out of the trans crossmember to get my angle right.

I've been hoping to get the motor fired up so I started to tackle the last little loose ends, battery, air intake, plugged off the extra return port on the power steering pump(hydroboost), got all the fluids filled. I built a temporary pod for a power switch, push button start, a fuse block and an oil pressure gauge. Powered everything up, pushed the start button, it cranked but not even a sputter. Hooked up a scanner and it was throwing a code because my ECT wasn't hooked up. The harness from the donor is very strange and doesn't match with any pin out or wiring diagram that I could find. I couldn't figure out how or where the ECT sensor wiring got to the ECU (have a whole other thread on this). Decided this harness and ECU had to get replaced. Only one I could find locally was drive by wire so I had to get the pedal, tac module, and a DBW throttle body to match it.

Round 2 on the harness rework.



I paid a guy to reflash the first ECU, but after reading a great thread by Gregski in the LS Swap section I decided to take the plunge and buy HPTuners and reflash this one myself. I made a trip to the junk yard and picked up a OBD2 port and some ECU plugs to make a bench harness so I could make changes to the ECU out of the truck. Plugged in and fired up HPTuners, did the simple stuff like removing Vats and all the emissions stuff.



Installed the new harness and ECU, pushed the button, still cranks and no start. Did some trouble shooting, injectors getting signal, but no spark. Ended up finding a ground for the coils that I forgot to hook up. Grounded that to the block, now I have spark but still doesn't even sputter. Checked for fuel, have pressure before the regulator but not a drop on the other side. Stopped by a few parts places today but couldn't find a replacement. Getting one from a friend so fingers crossed I'll be firing it up tomorrow!! I figured that if the regulator is plugged solid I should probably clean the injectors. They are getting a bath in my ultrasonic cleaner and some seafoam.



After almost 5 months I finally got my radiator from RnD. Took 6 weeks to ship, then UPS lost it, then found it but the fan was damaged, shipped it back to RnD to be replaced and took over a month to finish the claim so it could be shipped out again. FedEx had it at my door a week later! Long wait but its a very good looking product.

[Duncan K]

Turns out I had my fuel lines reversed, switched them around a it fired right up! Idles better than I thought it would without tuning.

https://youtu.be/o16voQxiL0I

[SCOTI]

Sounds good.

[sstock]

Spent a lot of time going through your build thread. Congrats of bringing this truck back to life, many would of walked right by it.
Sir you have mad skills.

Steve

[Duncan K]

Back to rust repair on the cab. Finished the driver side cab corner.



Moved on to the firewall/kick panel. This part is really tricky but I learned a lot from doing the passenger side so hopefully this side goes quicker

[Duncan K]

Cut, fit, weld, grind, repeat!! Slow and steady

[Captainfab]

Coming along nicely

[SCOTI]

Originally Posted by Captainfab

Coming along nicely

x2.

[Duncan K]

Got tired of sheet metal and rust. Decided to start on the exhaust. Ordered some stainless v bands, straight pipe, a few bends, and some Magnaflow mufflers. I plasma cut two holes in the cross member and welded in a couple support rings. Right after I cut the holes I found out that one header comes out closer to the frame rail so I would have to jog the pipe over to keep them parallel. Made a bunch of pie cuts to make the jog. Got everything tacked and started welding. I have never welded stainless before. Started with the v band which went ok, but once I moved on to the pie cuts not so good. Doesn't seem like i am getting very good gas coverage, welds are dark and have a crusty film on them. All the pieces were cleaned with acetone. Tried running a bigger #10 cup, upped the gas flow, nothing helped. I am not back purging so I wonder if impurities are being pulled in from the inside of the pipe?



Started on the "H" pipe, had to angle it to clear the driveshaft. I found a cool pipe notch template online which a printed, cut out and slipped around the pipe. Cut it out with a grinder and cut off wheel. Fit up was perfect.



Going to do some home work on welding stainless before I weld any more. Thinking about getting one of those monster size Furick Fupa cups with the diffuser and see if that helps.

[SkinnyG]

Looks a little hot. Try speeding up a bit. You kinda get the heat sweet and then boogie so you don't overheat the stainless.

Are you back-gassing, or Solar Flux?

[Duncan K]

Originally Posted by SkinnyG

Looks a little hot. Try speeding up a bit. You kinda get the heat sweet and then boogie so you don't overheat the stainless.

Are you back-gassing, or Solar Flux?

Yeah, I cooked it pretty bad at the beginning. Got my heat and travel speed dialed in a bit better on the last joints I did. Still not shiny and clean though.

No back purge, never heard of Solar Flux

[SkinnyG]

You need to protect the back of the weld. Back purge is good if you have the apparatus for it (a "T" and second regulator works well).

I've done Solar Flux B which is a powder you mix with Methanol and paint the backside - it prevents "sugaring" (looks like barnacles) and polluting the weld.

[tinydb84]

You are running too hot or too slow. With thin stainless tube I weld from 1 o'clock to 11 o'clock (I am right handed). When you run 3 to 12 it is welding up hill and building heat.

Definitely want to back purge the weld. That will help. I bought a second tank and another regulator. It was a tiny bit more expensive but now I never run out of gas on a weekend (the dual flow regulators are expensive!).

I run a #7 cup most of the time. Get a thin filler rod. You cool the puddle by adding more rod and it will absorb more heat.

[Duncan K]

Skinny, Tiny, thanks for the input!

Welds are getting a little better, but they are still not shiny. I had a cheap Chinese gas lens that wasn't sealing to the torch and was letting air mix with the argon. Changed that out for a CK lens and things improved right away.

I have a second Argon tank so I ordered another flow meter so I can back purge. Also have a Furick Fupa 12 cup coming.

[Duncan K]

I finished welding the h pipe section and moved on to the back section. Got the mufflers mounted where I wanted them. Tried a few different pie cuts and bends to get clearance from the trailing arms. Everything is tacked up ready for finish welding once my flow meter and Furick Cup arrives. The slip fit on the Magnaflow mufflers is really crappy. The diameter of the inlets on the mufflers are too big so the fit is really sloppy. I cranked the clamps down but the mufflers still wobble. The gap is probably too big to weld up so I'm not sure how I am going to solve this



Still need to make a few hangers. Not sure if I am going to just dump the exhaust out past the axle or take it all the way out the back

[tinydb84]

Good stuff! They make tail pipe expander tools though I don't know if they would work on stainless.

Can you post a pic of the fit of the tube in the muffler? You might be able to use a larger rod and walk the cup back and forth over the gap with the rod in between. Then do a pulsed cover pass to make it look nice.

[made2drag]

This build is awesome, cant wait to see more....

[Duncan K]

Back to work on the cab. Finished up the driver side floor, fit the rocker, all is great. Hung the door to make sure all the gaps were good and.............CRAP! Door doesn't fit in the opening. Looks like the front part of the floor is about 5/8 of an inch too high. Not sure what happened, there wasn't much left to measure off, everything was completely rotted out. had to cut the pillar, kick panel and across the floor, and then bend the floor down 5/8". Nothing like hacking up stuff you just finished replacing. I hung the door and what was left of the original fender to confirm fitment of the door this time. ended up having to push the rear pillar back a little as well to get the gaps right.



Pushing the floor down changed the angle of the firewall so I had to remove a piece of the kick panel to make it work. Took a lot of work to fix this mistake. Added the 5/8" to the pillar, kick panel and firewall and welded everything up, .....again!



Got the rockers welded in on both side, and patched a hole in the cowl.



This was a really frustrating mistake to make but I am moving forward again and I learned what not to do for next time.