Purchased a 1969 C10 Short Bed - Pleasanton, CA

[Luke87gt]

Tonight I put the kids to sleep, grabbed a beer, and replaced the valve cover gasket on the 250. I also gave the valve cover a degreasing before I bolted it back up.

The rockers look sludgy, let’s see if this 250 will come back to life.

[Luke87gt]

Also, I haven’t had a chance to trace these wires yet but wondering if you guys may know where each is going…

To clarify, there is a wire coming from the battery’s + lead into the pictured bank. Then there’s 3 additional wires coming off of that hot bank. Thanks

By the way, one thing I am not used to at all is how difficult it is to reach the back of the motor on these C10 trucks lol. For example, getting to those back valve cover bolts should qualify me for the next Olympic gymnastics trials

[SRU1436]

Originally Posted by Luke87gt

Also, I haven’t had a chance to trace these wires yet but wondering if you guys may know where each is going…

To clarify, there is a wire coming from the battery’s + lead into the pictured bank. Then there’s 3 additional wires coming off of that hot bank. Thanks

By the way, one thing I am not used to at all is how difficult it is to reach the back of the motor on these C10 trucks lol. For example, getting to those back valve cover bolts should qualify me for the next Olympic gymnastics trials

Attached is the wiring diagram for the truck. You’re talking about the junction block. I am not sure if the straight 6 has an additional wire. This will help you get started. If you trace them it will help you figure where they go.

The engine bays on these trucks are large, sometimes I use a small step ladder to reach the back.

[Luke87gt]

Thank you for that!

It looks like one of the wires runs to the fuse box. The other is labeled “Engine Ham” … what is that?

And then I need to trace the 3rd mystery wire on my 6cyl

[MikeB]

It's quite common to see other stuff wired to the junction block. But from the factory the junction block has a 12 gauge wire coming from the battery, and a second wire going through a 16 gauge fusible link, and then on to the "splice" on the drivers side of the radiator support. At the soldered splice, the battery wire is connected to the alternator output wire and the fuse panel feed wire.

It's been a while, but the mechanical regulator may also be connected to the splice.

If your truck has an ammeter instead of a warning lamp, the wire that runs from the battery junction block to the splice will actually be a resistance wire with tiny fuses on each end. The ammeter is actually just a voltmeter with "zero" in the center, and it responds to current flow and direction (charge/discharge) across the resistance wire. Kind of a strange way to do it, but I guess GM didn't want to run 30-40 amps into the cabin and use an actual ammeter.

[Steeveedee]

^ GM was smart to use a shunt, in my book. I've been under the dash of many a Mopar with scorched wires at the ammeter. Thermal expansion and contraction eventually created a weak connection.

[MikeB]

Speaking of resistance wire: On some GM cars, instead of a ballast resistor on the firewall, the wire from ignition switch to coil is a resistance wire, and it was bundled in with other wires under the dash.

I worked on a 64 GTO that was hard to start, and wouldn't rev like it should. Turns out someone had added an HEI but left the resistance wire in place, so the distributor was getting only around 9 volts. That resistance wire was melted into an under-dash wire bundle, so I replaced it with a 12ga wire. After that, the engine started easy and revved well. But I had aches and pains from lying on my back!

[Luke87gt]

Well it’s been a motivated weekend. I managed to get the 275/60/15 BFGs onto the 15x8 4.0” BS truck rally wheels.

Not on the truck yet but looks to be a big improvement over the wheels the truck arrived with.

[1970cstblazer]

Still has at least one original T3 headlamp bulb!

[Luke87gt]

Originally Posted by 1970cstblazer

Still has at least one original T3 headlamp bulb!

Wow, how can you tell that 😀

[Luke87gt]

I will say that I am not used to the weight of these truck rally wheels.

I’m not sure what each weighs but it’s by far the heaviest wheel I’ve ever handled on a vehicle lol.

Each wheel needed 2-3oz of weight to balance out. With typical lightweight alloy sedan wheels, I typically need 0-0.5oz to balance.

Tire shop didn’t seem concerned and said although more weight is sometimes needed for steel truck wheels, they balanced out fine in the end.

[1970cstblazer]

Originally Posted by Luke87gt

Wow, how can you tell that 😀

The triangle in the middle of the bulb.

[1970cstblazer]

Originally Posted by Luke87gt

I will say that I am not used to the weight of these truck rally wheels.

I’m not sure what each weighs but it’s by far the heaviest wheel I’ve ever handled on a vehicle lol.

Each wheel needed 2-3oz of weight to balance out. With typical lightweight alloy sedan wheels, I typically need 0-0.5oz to balance.

Tire shop didn’t seem concerned and said although more weight is sometimes needed for steel truck wheels, they balanced out fine in the end.

Those wheels were originally solely on 4wd Blazers Suburbans and 1/2 ton trucks, so they had to be stout.

[Luke87gt]

Originally Posted by 1970cstblazer

The triangle in the middle of the bulb.

Ahh, I see that on the lens

[fourspeedwagon]

Originally Posted by Luke87gt

Thank you for that!

It looks like one of the wires runs to the fuse box. The other is labeled “Engine Ham” … what is that?

And then I need to trace the 3rd mystery wire on my 6cyl

My guess is that says “Engine Harn.” short for harness. Not sure on the reason for such frugal use of ink there

[Luke87gt]

Via online search I’m seeing an estimate of ~70lbs for a 15x8 truck rally with 275/60/15 tire. That means 280lbs of wheels! What a handicap!

I love the look of these wheels but might have to rethink these over the long term as I get into improving the handling, braking, and acceleration of the truck.

[Rust_never_sleeps]

Originally Posted by Luke87gt

By the way, one thing I am not used to at all is how difficult it is to reach the back of the motor on these C10 trucks lol. For example, getting to those back valve cover bolts should qualify me for the next Olympic gymnastics trials

I'm 6'5" and I have to use a stool to comfortably doink around with the alternator etc. back there for more than a few minutes
Of course, then I bang my head on the hood a lot
The truck always wins

[MikeB]

Originally Posted by Luke87gt

I will say that I am not used to the weight of these truck rally wheels.

I’m not sure what each weighs but it’s by far the heaviest wheel I’ve ever handled on a vehicle lol.

Yes. Even when I was 20 years younger, they were a b|tch to pick up and put in place. Now I set them on a 2x6 and wobble them on. Even then, it's tough to do.

[Luke87gt]

Originally Posted by MikeB

Yes. Even when I was 20 years younger, they were a b|tch to pick up and put in place. Now I set them on a 2x6 and wobble them on. Even then, it's tough to do.

Thanks for sharing. I’ll probably make my first attempt at actually bolting those wheels up to the truck next weekend and will report back on the fun 😀

[Luke87gt]

Finally got the wheels mounted. Looks much much better than the previous wheels.

15x8 rally 4.0” BS
275-60-15 BFG Radial T/A

I did run into a roadblock in that one of the center cap bolt holes was stripped (didn’t notice that when I was buying the wheels).

I wrapped the center cap bolt in copper wire and that did the trick. Not necessarily a permanent fix (may have to heli-coil) but fine for now.

[68bowtie]

Looks good

[yuccales]

They look great!

[Luke87gt]

Thanks guys, I also thought this was interesting.

The spare tire the truck came with was a “JCPenny” brand tire. I assume it’s original?

[70 shorty]

A JCPenny brand tire would not have been original.

[1970cstblazer]

JCP has been out of the auto business since 1983.