1973 GMC K2500 Camper Special

[Jason S]

Here are some photos of my '73 GMC K2500 Camper Special.

Prior to propane install.

[thirsty]

Great looking truck. That color is awsome for a truck like that.

[Jason S]

Thanks Thirsty.  That is the factory color, I think it's called Green Gold Metallic.

The bed is a later mode that went on after i slid off an icy road coming back from a hunting trip. While i kind of miss the flush mount fuel filler caps, I don't miss the fuel streaks that seemed to be a regular occurrence.

Here are some more photos after the propane install.

[zieg85]

Great looking ride, love the stock stance, hubcaps.  The newer style front bumper doesn't look to bad either.  What is it that is sticking out used for?

[Jason S]

Photos under the hood with propane.  The engine is filthy right now, but she ran fine all summer with 115 degrees outside temps while blowing cold air in the cab.

The first photo is looking at the passenger side of the engine compartment showing the Impco Model gas regulator with an electric fuel lock-off valve. There is a vacuum operated lock-off that could be used in lieu of the electric lock-off.  The lock-off is simply a valve that is normally closed unless electricity (or vacuum) is applied. So if I have the switch in the cab flipped to gasoline, it will open the lock-off on the gasoline line to the carburetor and the propane lock-off will remain closed (and vice-versa). 


The second photo shows the Impco 300 propane carburetor, air cleaner and adapter sitting on top of the Quadrajet carburetor.  When operating on propane, there is a cable actuated air valve that closes off air from passing through straight to the gasoline carb. When in propane mode the engine vacuum passes through the propane carb and pulls the propane gas from the regulator  (through the black tube) to the propane carb where it is mixed with air, which then passes through the Q-jet into the intake manifold. 


The third photo pretty much shows the whole underhood propane setup, with the regulator on the passenger inner fender and the mixer/carb on top of the Q-jet.


The fourth photo is a closeup of the Impco Model E propane regulator. The Model E is supposed to be cable of supplying a sufficient amount propane gas at least a 454 cid engine. Smaller displacement engines (like most 6 cylinders) would use a smaller regulator.

[Jason S]

Thanks Zieg. 

It's sitting on an older Rancho 4" lift, I think it's just about the right height for me.

The bumpers, front and rear, are CUCV.  The black pieces sticking out are where the clevis' attach.  I have a Pierce 9,000 lb worm drive winch that I mounted in a special cradle that will bolt up to the front clevis attachments and lower frame.  I'll probably wind up building a dedicated winch bumper sometime, but right now I can remove/install the 250 lb behemoth if I want. 

Here are some photos of the dash cluster and the Spicer lockouts.





The NP203 has a part time conversion and had some Warn lockouts when I bought it way back when. I had wanted Spicer hubs for a long time. About 10 years ago I called Spicer and ordered their current hubs, Powertrain, but they were essentially the same as the Warn hubs.  I found a decent set of Spicer Hub-Lok external lockouts about 6 years ago and swapped them for the later style.

[zieg85]

Nice stock touches, tach, stock radio...very nice.  I had those type of hubs on my 72 K20, never had any problems with them.

[thirsty]

[Jason S]

Thanks Zieg and Oilzum.

 As far as the Spicer hubs go, I guess I'm going to have a post about them.  I'm looking for some parts, specifically O-rings, that may or may not still be available.

[VileZambonie]

This

[bake74]

     That really is a nice looking truck.  Don't worry, only a select few will know that the bed is of a later model from the gas caps.

[Engineer]

I approve.

[JohnnyCanuck]

Nice, how much is propane down there?

[Macj1983]

What's the draw of going to propane? Versatility ? In a newbie to most of this stuff

[Jason S]

Thank you, Vile, Bake, Engineer & JohnnyCanuck.

Currently propane is $2.65/gallon as a motor fuel with alternative fuel tax decal. In Oklahoma, if using an alternative fuel (other than gasoline) you are required to pay road taxes or purchase a tax decal yearly (that goes in the lower right of the windshield).  Yes, I drive an alternative fueled vehicle.

I like the propane because my engine has to have at least 89 octane ($3.35/gallon now).  I can drive the '73 GMC to work and pay a little less in fuel than I would to drive my 2005 Chevy and save the miles on the newer truck.

In my experience thus far, propane on an older truck:  it is essentially a "poor man" fuel injection when it comes to start up. I will get it fire up by the third crank in the morning (summer or fall) and then can literally drive away; oil is golden colored at oil change; it's about 115 octane so you'll never have pinging;  it burns very clean; no flooding; never a bad batch of fuel and so on.

The downside:  It has about 85% of the energy content of gasoline, so not as much getup and go; I have to go to a propane supplier to buy fuel; I gave up about 2' of bed for my tank; there is a certain amount of oil in propane and that oil will accumulate in the regulator and propane carb, requiring cleaning; and a few other drawbacks.

This truck is dual fuel right now and the ignition is set for gasoline (timing and plug gaps).  Compression on the 350 is about 9.1: 1, the compression ratio could be increased if this was a dedicated propane truck. However, at present I can run gasoline or propane.  Plus, with the setup I have, I figure that if both 20 gasoline tanks were full and the 100 gallon propane tank was full (i.e., about 80 gallons) , then I could drive over 1000 miles without having to fuel up...