1968 GMC - Ol' Blue

[MDPotter]

Originally Posted by AlexBC

Holy Crap! You did an incredible job! I wish I had 1/10th the patience you have to do the body work. What a beautiful truck!!!!

Thanks! I'm jealous of your coil rear end and wheels. Leaf springs suck!

[MDPotter]

Originally Posted by rodstored-72

md,
very nice job on the fans and the CFM verification. I purchased my radi/fan setup from summit. supposedly the fans indicate that their CFM is equal to what the factory fans did for my engine. I will also wire mine up to do the same as you indicated - first fan on full until temp/ac comp. kicks on and then kick the 2nd fan on. thanks for the build updates!!

Thanks. It's probably the safest bet. If you can find the wattage on your fans that will tell you about how much CFM they pull.

[TA_C10]

Originally Posted by MDPotter

Hope everyone had a great Easter!

So I knew the fans that came on my radiator were cheap and destined to be replaced soon so I went ahead and did it. I bought this radiator and fans on eBay and the fans were advertised as 1,228 CFM each. Through some research, I found them on Amazon for $20 a piece from a company called UPGR8. I compared them to a Spal fan rated at 1,200 CFM and noticed that the Spal fan pulls double the wattage and that confirmed for me that they are falsely advertised. Interesting that the eBay seller has since revised the details in the item listing to not indicate any fan CFM. So anyway, I bought these Spal fans rated at 1,451 CFM each. Wired them up, worked as they should and definitely moved a lot more air. It took several minutes at 3,000 RPM to get the engine up to high temp for both to kick to full speed. I noticed that running them full speed that the volt meter would drop by about 1 volt (down from 14) and the fans would slow a little bit for a couple seconds, then return to normal. This happened every 10 seconds or so. I'm not sure what's that about, but later that day I stumbled on some info on the internet saying that Spal fans are not supposed to be ran at half speed/half voltage. I wanted to hear it from Spal so I called this morning and sure enough, the tech rep indicated that it would "prematurely" wear out the motors running them in series. So I guess I'll be rewiring my fans so that one fan is on full speed when the engine reaches low temp and then the second fan kicks on at high temp (also A/C high pressure). This is the case for Spal fans, but I don't know about other manuf's. I just assumed that this would be okay since GM does it, but the fans GM uses must be designed for it. So we enlarged the holes in the shroud and I was happy with the fit and quality of these fans.

Also replaced the front shocks due to the increased drop from where I had it originally.

.

[MDPotter]

Fans are rewired. Here's the sequence of operations: when coolant temp reaches 195, fan #1 comes on full speed. When coolant temp reaches 205, fan #2 comes on full speed. When A/C line pressure reaches 254 psi, trinary switch closes and sends ground to fan #2. I did this because I found out my Spal fans are not 2-speed fans and running them in series at 6V instead of 12V will wear them out. This is actually a much simpler wiring schematic so I didn't mind. The resistor and diode are important because the PCM will see a ground through the trinary switch without those components and throw a code. The direction of the diode (basically a check valve) is important too. We put it in backwards the first time and the electricity could not flow through the diode. For the ignition source, I used the electric fan wire from the American Autowire harness. I posted a link to the diagram below for anyone that would like it.



Speartech Fan Relay Wiring W TRINARY SWITCH.pdf

[MDPotter]

Also was able to spray the underside of the bed floor, tubs, tailgate handle, and skirts with epoxy. I sprayed three coats of SPI epoxy and this will be the final coating for these parts. Next weekend I'll shoot Raptor Liner to the topside of the floor.

[clay68c10]

Nice progress, you'll be ready for summer.
How do you like that fuse/relay box? It looks like the same one I bought off Amazon.

[MDPotter]

Originally Posted by clay68c10

Nice progress, you'll be ready for summer.
How do you like that fuse/relay box? It looks like the same one I bought off Amazon.

Thanks! The bed is taking longer than I anticipated, but it should be on the road in June.

The fuse box is good, I'm happy with it. I've used 10ga wire on the connectors; it's not easy, but it can be done. I solder all the connections too. Just make sure you get the seals on the right way (the relay gaskets can be put in upside down). You can slide the gasket over the wires and then make up your connectors, but it's also possible to stretch the gasket around the connectors (easiest if you have another person to stretch it while the other pushes the connector through). I couldn't figure out how to pull the connectors out of the fuse slots without breaking a little plastic tab off, so that's why you see a couple slots between fuses. Once that plastic tab in the housing is broken off, the connector won't stay in.

I looked at the Bussman center as well since it's so cool and commercial-looking, but you end up having to buy like 50 or 100 minimum of the connectors and gaskets and there are different sizes for different size wires so you end up spending like $150 on the center, connectors, and gaskets and only using a few so I decided to go with this one since it comes with all those for a lot cheaper.

[clay68c10]

I thought the same about that Bussman. If the terminals weren’t an issue it would be a solid choice.
Thanks for the heads up. Hopefully I’ll be doing some wiring this summer.

[MDPotter]

I'm starting to see the light at the end of the tunnel on the bed. I sanded the bedsides, the tubs, and the floor with 180 and then sprayed 2 coats of epoxy.

[MDPotter]

The next day, I sprayed two coats of Raptor Liner on the floor. It's hard to get it to look even with such a small pattern on the Raptor gun, but by the end of the day it had flashed off and you could hardly see the lines. The tailgate and front panel are nice and smooth from the factory so I won't need to do anything prior to paint on them.

1st coat:


2nd coat (right after spraying):


After drying about 6 hours:

[cornerstone]

The raptor liner really looks good, and I’d bet after it gets just a little bit of use you won’t be able to see any spray lines. Is raptor liner different that a standard bed liner or just another brand?

Did you add any filler to the bedside that arrived dented? It looks too straight to only have popped out the dent, or are you just very good with a hammer and dolly?

[MDPotter]

Originally Posted by cornerstone

The raptor liner really looks good, and I’d bet after it gets just a little bit of use you won’t be able to see any spray lines. Is raptor liner different that a standard bed liner or just another brand?

Did you add any filler to the bedside that arrived dented? It looks too straight to only have popped out the dent, or are you just very good with a hammer and dolly?

I've only used two different bed liner products. The first one I used, years ago, was a roll on Herculiner and it sucks. It rolls on and is paper thin. This Raptor Liner is a spray product and goes on thicker and I'm really happy with it so far. Raptor Liner seems to have a great reputation and is widely used from what I've seen on here and the SPI forum.

I did apply some filler to the damaged bedside, along with the shaved stake pockets and the inner bedrail edge to cover up spot welds. The picture I took is of the good bedside. I'm far from very good with a hammer and dolly.

[Camaroguy]

Are you planning to top coat the raptor lining with body color or leave it black? Looks good, and you're way ahead of us.

[MDPotter]

Originally Posted by Camaroguy

Are you planning to top coat the raptor lining with body color or leave it black? Looks good, and you're way ahead of us.

I'm just leaving it black. I thought about tinting it, but wanted a little contrast.

[Camaroguy]

Originally Posted by MDPotter

I'm just leaving it black. I thought about tinting it, but wanted a little contrast.

I'll admit, I am not up to speed on this stuff but would be concerned about it fading. I am sure it will look nice either way. Again, good job on the truck.

[1971Stepside]

I'm having this shot on the inside of my rear fenders and front inner fenders to keep the rock dings and stars down. Looks like good stuff.

[67_ShortFleet]

Originally Posted by MDPotter

The front end lighting is done. I bought the halogen upgrade headlights from LMC and I'm pretty pleased with them. They use a modern 9007 lamp and I opted for the blue-coated lamps for whiter light. Working with 4 headlights makes me jealous of you Chevy guys - it's twice the struggle and there's barely enough room in front of the core support for the housing and lamp pigtail so the wires are almost stressed on the inners. Also, I couldn't remember how the spring hooked on the buckets so I fought that for awhile.

But the LED sidemarker lights from SOKY were easy to install and look great too.

I need to figure out how to reset the glass in the channels though. I haven't been able to find much info on this task yet. It seems from the factory they were just pressed in with some rubber without any adhesive. I ordered the "glass setting rubber" from LMC and it's basically just strips of rubber. The passenger glass fell out of the channel during door disassembly so I took the driver side apart and sandblasted and painted the channels while I was at it. If anyone has any tips on this, let me know please.

Attachment 1971844

Attachment 1971845

Attachment 1971851

Attachment 1971852

Nice build, do you have any pictures of how the headlight buckets are supposed to be? They are messed up on my GMC and I 'm having trouble figuring out what the problem is.

[MDPotter]

Originally Posted by 67_ShortFleet

Nice build, do you have any pictures of how the headlight buckets are supposed to be? They are messed up on my GMC and I 'm having trouble figuring out what the problem is.

You mean how the buckets attach to the core support? I can take a few pictures of the buckets, springs, and adjusters if that's what you're looking for. Install was kind of a pain.

[67_ShortFleet]

Originally Posted by MDPotter

You mean how the buckets attach to the core support? I can take a few pictures of the buckets, springs, and adjusters if that's what you're looking for. Install was kind of a pain.

Yes, that is exactly what i'm looking for!

[Jolin]

MDpotter was there much effort need to get those headlight to fit? Did you upgrade the harness? thanks

[MDPotter]

Originally Posted by Jolin

MDpotter was there much effort need to get those headlight to fit? Did you upgrade the harness? thanks

They were pretty easy to install. I didn't do the headlight relay upgrade - I'm running the factory setup. The plugs on these headlights are a little large and connectors/wiring on the the inner (high beams) headlights are pushed up against the core support. Not ideal, but seem to be okay. There isn't a hole behind the high and low beam buckets in my core support, but it would be better to drill a hole behind the high beams in the core support for clearance on those connectors. Other than that, they fit the buckets and trim rings just fine and the wiring was easy.

A tip: run your wires the way you want them to run and have them sticking out through the buckets and then install the connectors. If you don't, you'll find out that the connector won't fit between the bucket and the core support.

[Jolin]

Thanks, My build is real similar to your. A little darker blue LQ4 4L80E, Coil springs, the same Tanks tank (hopefully I will not have any leaks my bed is on). I am in the process of wiring, I may be bugging you some more. thanks for your help.

[MDPotter]

Originally Posted by Jolin

Thanks, My build is real similar to your. A little darker blue LQ4 4L80E, Coil springs, the same Tanks tank (hopefully I will not have any leaks my bed is on). I am in the process of wiring, I may be bugging you some more. thanks for your help.

I'm here to help, so ask away.

On the fuel system - I would recommend Earls Vapor Guard hose and fittings. Also use Rectorseal 5 on the pipe thread fittings. AN fittings seal great, but pipe thread not so much. I ended up using Rectorseal 5 on a couple pipe thread fittings on my brake lines to fix a leak. So pressure up your fuel system before you put the bed on, check for leaks, and use a Wix filter instead of the generic filters.

[MDPotter]

Originally Posted by 67_ShortFleet

Yes, that is exactly what i'm looking for!

Here are a few pictures for you.

[Jolin]

thank you those help a bunch