1970 C-10 / 1998 Yukon hybrid

[bodydropped68]

Originally Posted by notchbackgta

should be 5/16"-18

that would be the size to attach the cowl panel to the body

[colgad]

Great build, I have a friend wanting to do this. This will be a great guide.

[mechanicalman]

Originally Posted by carsonmx114

Hey guys, I'm new to the forum. I've been searching C-10 stuff for weeks and I kept landing on this forum. I thought I'd share some pics from my C-10 project I just started. My plan is to put a rat rod style C-10 body on a 4X4 Yukon frame retaining all the factory options except the air bags. I'm thinking I'll go with 20" wheels but I'm waiting on that until I get the body situated on the frame so I can get the offset correct. I'm planning on using the floorpan and firewall from the Yukon since the mounts will bolt right onto the frame. Also the steering column and HVAC components will bolt right in, I hope...

Sub'd. Welcome to the forum, I'm going to be riding your coat-tails on this one. I've got a 68 cab and a 92 C1500 that I want to splice together. I'm all eyes and ears on this one!

[mechanicalman]

Originally Posted by carsonmx114

Hey guys, I'm new to the forum. I've been searching C-10 stuff for weeks and I kept landing on this forum. I thought I'd share some pics from my C-10 project I just started. My plan is to put a rat rod style C-10 body on a 4X4 Yukon frame retaining all the factory options except the air bags. I'm thinking I'll go with 20" wheels but I'm waiting on that until I get the body situated on the frame so I can get the offset correct. I'm planning on using the floorpan and firewall from the Yukon since the mounts will bolt right onto the frame. Also the steering column and HVAC components will bolt right in, I hope...

Are you going with a short bed, conventional or an inch and a half longer?

Are you going to alter the wheelbase?

[bodydropped68]

Originally Posted by colgad

Great build, I have a friend wanting to do this. This will be a great guide.

X2

[bodydropped68]

Originally Posted by mechanicalman

Are you going with a short bed, conventional or an inch and a half longer?

Are you going to alter the wheelbase?

here you go from the OP
If the numbers I found are correct the wheelbase is 2.5 inches longer than the C-10 SWB. My body is a LWB so I was already planning to shorten my bed anyway

[notchbackgta]

Originally Posted by bodydropped68

that would be the size to attach the cowl panel to the body

Oops, I wasn't thinking. Thanks

[bodydropped68]

No problem your project is looking good. A friend just wrecked his 99 tahoe and that has my son thinking about the same conversion for his 72 I told him lets do it.

[carsonmx114]

Thanks guys for your comments and input. I got the pedal / column bracket welded in. I hung the brake pedal and slid the seat in to check the seating position. It feels fine and the extra leg room is nice. I hope to make some brackets to mount down the front clip this weekend and bolt the backs of the fenders to the cab to get everything lined up.

[markmdz]

I'm amazed at how quickly your projects come together.

[mechanicalman]

Originally Posted by carsonmx114

Thanks guys for your comments and input. I got the pedal / column bracket welded in. I hung the brake pedal and slid the seat in to check the seating position. It feels fine and the extra leg room is nice. I hope to make some brackets to mount down the front clip this weekend and bolt the backs of the fenders to the cab to get everything lined up.

Wow. I was wondering about that legroom, you have made an improved product and with the perimeter frame gas tank, you now have cab room galore.

I'm still trying to figure some things out. I do not intend to use the wiring harness on my 92 and intend to retain the stock 72 gauges. I intend to use a TPI computer/harness, probably a painless harness as the stock harness is so COMPLICATED. We'll see on that if I'm willing to buy a new harness then there is nothing to lose if I hack up the old Camaro harness. I figure I will need a speed sensor at the trans. Right now I'm running an MEFI3 adapted into the stock harness and an adaptor in the engine bay for the ramjet style fuel injection. It would be nice to keep the 92 tank (has the high press FI pump) and the rear spare tire/wind-up, then the cab tank goes buh-bye and I have a safer tank that in cab OR rear mount and get to keep my spare tire out of sight. And the 700R4 is nice with the 3.73 gears. I would have to live with the leaf springs. I assume you have coil springs in the rear.

I want to see how you do the core support; I want to retain the 72 core support if possible.

I found pictures of where a guy did the same thing kinda only he kept the early model cab intact. However, it was a 4WD so he was able to raise things the proper amount and made custom cab brackets. I'm not sure by my initial measurements if I can do that with a 2WD, in particular in the gas tank area.

Also, I see these later model frames (like my 92) have a "slip joint" assembly the factory used to simplify the production line near the front of the frame. IMO that would make shortening the frame much more feasible as my driveshaft yoke actually hangs out the back of the trans 2.5" giving me about 1.5 inches I could shorten it, that gets me close. I'm hoping to use the 92 stepside bed with modified rear wheel openings but not sure I may have to get another bed.

Now that you have modified the firewall, is there anything you would do different? Are you going to lose the stock 72 glove box area, or are you going to modify it?

[carsonmx114]

So you have a Camaro TPI engine in a 92' chassis? That looks impressive. Does your 72' Have A/C? I don't think I'd buy a high dollar wiring harness. I made my stand alone harness from the factory Corvette harness when I built my 911. I just laid the harness out and using a pinout diagram I started pulling out the wires I wasn't gonna need. I ended up with a handfull of wires. Switched, constant power, ground, fans, fuel pump, tach. Not a bad deal at all. Much easier than you might think.

I think the hardest part of my build will be the cowl / air box intake area. I've settled in on using the floor of the Yukon box to fill in the gap between the Yukon firewall and the C-10 air box. My new firewall will have a bumpout on the passenger side to house the fresh air intake and hold the coolant overflow tank. I'm planning on using the Yukon wiper setup so I can get the interval wipers and get the wiper setup out from under the dash.

[mechanicalman]

Originally Posted by carsonmx114

So you have a Camaro TPI engine in a 92' chassis? That looks impressive. Does your 72' Have A/C? I don't think I'd buy a high dollar wiring harness. I made my stand alone harness from the factory Corvette harness when I built my 911. I just laid the harness out and using a pinout diagram I started pulling out the wires I wasn't gonna need. I ended up with a handfull of wires. Switched, constant power, ground, fans, fuel pump, tach. Not a bad deal at all. Much easier than you might think.

I think the hardest part of my build will be the cowl / air box intake area. I've settled in on using the floor of the Yukon box to fill in the gap between the Yukon firewall and the C-10 air box. My new firewall will have a bumpout on the passenger side to house the fresh air intake and hold the coolant overflow tank. I'm planning on using the Yukon wiper setup so I can get the interval wipers and get the wiper setup out from under the dash.

Sorry for the mis-communication. It's not a Camaro engine, it's a 350HO 330HP crate engine with a Mercruiser (what Ramjet 350 is based on without the GM Performance logo) MEFI3 upgraded to 02 and IAT feedback. It's not well calibrated (I have to dilute fuel with E-85) and it does not control EGR or TCC. The MEFI3 is wired to an adaptor that plugs directly into the 92 C1500 harness and the TBI wires have been spliced into 8 injectors that batch-fire. Ceramic coated tri-y headers have an EGR built in and I'm using external plumbing to the plenum.

I have an 86 TPI computer, harness, MAF and all the sensors; I want to use it to control it so I will have EGR, TCC, and canister purge then I can run just plain gas. I have the equipment to burn the TPI chips (used to have an 88 formula TPI 350), and I'm too cheap to buy the set-up to calibrate the MEFI3; it won't control everything I want anyway. I've been too lazy to install it because I want to do it when I do the cab change. I think I have room for the MAF next to the air cleaner, so the MAP will just be a dummy after that on the intake. Obviously I want to keep the fuel pump system intact as it's already converted to PFI pressure.

I got all the pin-out diagrams on the TPI system and I recently picked up a Packard wiring repair kit with all the connectors and crimper, so I'm more ready to dive into it. I plan on only using the wires I need to keep the computer happy and the FI and use the stock 72 C10 harness for everything else except I'll need to power the rear only anti-lock brakes. I may try to use the steering column so as to use the cruise control, intermittent wipers. I got some planning to do and then a lot of work.

The body on the 92 is all beat up from the Great Arizona Hail Storm of 2010, paint peeled, blow-out damage on the bedside, busted windshield and brittle, busted all to heck plastic dash.

My 72 C10 is factory A/C, however I would like to somehow use the A/C unit from the 92 but not sure it's possible. For sure I'll keep the R4 compressor, and if it ever fails it gets a Sanden. I may have to use more of the 92 wiring than I was thinking, shoot probably most of it. I may just re-route some of the wires and just rob the connectors I need from the 86 harness.

If you have any more pictures of the firewall work I'd love to see them. I think I will for sure have to do something similar.

[mechanicalman]

BTW, that orange GMC is just a rendering of what I want my 92 stepside bed to look like with rounded fender openings to match the front.

[mechanicalman]

I assume the cab had to mount that far behind the Yukon firewall in order for the front fenders to center on the Yukon chassis?

[garmar]

Wow, what an ambitious project. You appear more than up to the task. I'll be watching this one.

[carsonmx114]

Garmar, Thanks for the compliment. I'll feel a lot better when I get this cowl business sealed up!

Mechanicalman, You should check me but I believe the later model cab is just longer. I feel like the support under the floor behind my seat will be the same support that is at the back of your cab (92' cab). I sawed the floor out of the C-10, set it on the frame with the front clip and centered the wheels in the wheel wells. I then measured from the center of the rear mounting holes on the frame to inside wall of the back of the cab. I measured that distance back from the mounting holes on the floor, taped off a straight line and sawed the back of the floor off square. I then set the cab back on the frame with the Yukon floorpan bolted on, set the height and tacked it in place.
As for your engine, and I ask this out of ignorance because you obviously know a lot more about EFI stuff than I do, why couldn't you get a 2000 or so computer and set it up to run standalone on your existing components? I had a guy convert my LS1 to speed density a few months ago and it's awesome! I have no MAF sensor at all now. 4" air filter into a 4" tube with a IAT sensor in it into a 4" elbow then straight into a 4" throttle body. That way you could get away from the batch injection and the MAF sensor too.

[carsonmx114]

Hey guys, I've been working on the firewall situation in my truck some. This latest round of global warming kept me in the house last week. It's not as fun to work with a kerosene jet heater roaring in the background. I lifted the cab back off yesterday to finish welding the floor pan in and finish out the cowl. I plan on painting the firewall before I set in back on too. After that I should be ready to start bolting parts back on!

[mechanicalman]

Originally Posted by carsonmx114

As for your engine, and I ask this out of ignorance because you obviously know a lot more about EFI stuff than I do, why couldn't you get a 2000 or so computer and set it up to run standalone on your existing components? I had a guy convert my LS1 to speed density a few months ago and it's awesome! I have no MAF sensor at all now. 4" air filter into a 4" tube with a IAT sensor in it into a 4" elbow then straight into a 4" throttle body. That way you could get away from the batch injection and the MAF sensor too.

I don't see any ingnorance, not sure I know more about EFI LOL.

I would love to get rid of the batch injection, not worried about losing MAF especially if I had the big MAF that comes with later model injection. I can understand on the Porsche the need for that however. BTW, that thing is AWESOME.

I never considered an LS1 computer due to the older style ignition on my engine, and never considered an L31 computer due to the "spider" injection, but you have me thinking maybe it could be set up to run on my existing components. Could you send me a PM and refer me to your guy so I could make an inquiry?

Thanks

[flashed]

This global warming crap you speak of sucks big time ,its causing me to spend too much time at work but the overtime will help me to be able to play with my 1 ton soon I hope .In the meantime I just watch what you and everyone else here is up to.

[carsonmx114]

I got my filler panel over the firewall finished and welded in over the weekend. I hope to get the firewall sanded today and ready for paint. Then I'll be ready to go back on with the cab and start re-installing the wiring. I'll post some more pics after I get it trimmed and set back on the frame.

[72mike]

So what happened, how's it coming along?

[carsonmx114]

I haven't gotten much more done on my project lately. When I drove the Yukon home it was missing 1st gear and slipping in 3rd so I knew I had transmission issues going in. I pulled the trans and took it for a rebuild. It seems that it's so jacked up inside that it's not a viable rebuild. So I'm in the market for a 4L60E. I didn't want to bolt the cab back on until the trans was back in because it's not everyday you can remove and install a trans from the top and it's SO much easier.

[72mike]

It's been months, would like to see where this project sits...