Propane-powered big block GMC

[72_gmc_suburban]

I'm looking at a 70 GMC, 1-owner C20 truck. Everything seems great with the truck so far. Little/no rust (it has lived in the southwest its whole life) and nearly all the available options for that year. (no tach, no sliding rear window, but everything else) He also has full documentation of the vehicle's history.

The only question mark in my mind is the truck has been converted to run on either propane or gas. I know *zero* about propane-driven vehicles, so am turning to here for help.

The truck has 230k miles on it and, according to the owner, ~80% of that has been on propane. Is this a good thing, a bad thing or pretty much indifferent? Anything special/unique I should look for when I inspect the car tomorrow? Anything to be aware of specific to propane-driven vehicles?

Thanks

[Shyguy]

A lot of farmers here run propane powered engines on the irrigation pumps because propane does not contaminate the engine oil like gasoline does.

[bigdog57]

I wore out two different trucks with it and i just converted my 70 gmc over to it. It's a verry clean burning fuel. I hav also gone cross country on it with no problem getting refills.

[72_gmc_suburban]

Originally Posted by Shyguy

A lot of farmers here run propane powered engines on the irrigation pumps because propane does not contaminate the engine oil like gasoline does.

Yeah, he mentioned going 20k between oil changes, which I thought was odd. I care less about the condition of the drivetrain than I do the body, so I didn't worry about it too much, but sounds like that might be normal?

[72_gmc_suburban]

Originally Posted by bigdog57

I wore out two different trucks with it and i just converted my 70 gmc over to it.

What's involved with "converting" an engine over to run on propane? What has to be changed?

[bigdog57]

Its pretty straight foward. I had the propane people to install on the first two trucks. But they told me that my 70 was to old for them to it. They told me how to do it and sold me the parts that i needed. I already had the tank and regulator vaporizer. They sold me the carb(bolts on top of the regular carb) and the rest of stuff (like hoses and the switch inside the cab to change from gas to propane

[mrein3]

Originally Posted by 72_gmc_suburban

I'm looking at a 70 GMC, 1-owner C20 truck. Everything seems great with the truck so far. Little/no rust (it has lived in the southwest its whole life) and nearly all the available options for that year. (no tach, no sliding rear window, but everything else) He also has full documentation of the vehicle's history.

The only question mark in my mind is the truck has been converted to run on either propane or gas. I know *zero* about propane-driven vehicles, so am turning to here for help.

The truck has 230k miles on it and, according to the owner, ~80% of that has been on propane. Is this a good thing, a bad thing or pretty much indifferent? Anything special/unique I should look for when I inspect the car tomorrow? Anything to be aware of specific to propane-driven vehicles?

Thanks

Far from indifferent. Propane and natural gas converted gas engines run way cleaner than an engine that burns gasoline. Thus the 20k between oil changes like he quoted you.
If its rust free don't let the 230k scare you. That thing is just broken in.

I understand without a computer controlling the timing you have to compromise on which runs better, gas or propane. My understanding is that propane needs more advance than gas.

[VA72C10]

Sounds like a really cool truck...and if you're thinking modern drivetrain I'd say go for it (the truck)! Might be able to sell the engine w/ the propane conversion stuff for some money to recoup your other costs...

[72_gmc_suburban]

Thanks for all the replies. I took a look at the truck today and, while it's definitely not in rough condition, it's also not in fantastic condition, either. He's let it sit the last few years (guy was ~75 years old) and, since he's the original owner, he's way too emotionally invested in the truck to see it for what it's really worth, which is not what he's asking for it.

So, this one ended up being a pass. Appreciate the help from the board, however.

[VA72C10]

Oh well...there's a lot more out there...

Been in that case many times (worth more to the owner than it's really worth in this economy)

[stsalvage]

that's strange i know a lot about it But hardly any one uses it do to how expensive it is to buy here4 on the west coast You know your only have a 20,000 mile engine.I have framers out in AZ and CA that have wells they pump water from for orange tree's I use to go buy and listen to the old men talk about the war women and other things.

They had 3 pumping stations 2 of them have 1 427 side oilier ford big block and the other 2 where chevys one was a 427 chevy and the small well had a 396.

I asked the old man when they sold the property what will happen to the engines He told me the ford engine was sold for 6,000 and the 427 chevy was undecided i asked the guy what about the 396 The old man said they where going to junk it I asked the guy is i could buy it for 50.00 so i got it

My uncial had a 1966 3 ton Bobtail that had a 366 in it It throw a rod 1 month after i bought the 396 My father asked if Tom could have the 396 So he paid me 300.00 for it.

My uncial tom said he was going to rebuild the 396 cause it looked like it was tired and was all greasy the valve covers where leaking the pan was the same.He wanted to go to a 4 bb crab instead of the 2 bb.

He opened that motor up and he was screaming into the phone All i herd was I hit the jack pot later he showed up with the engine token apart.

they took The mick tool to the crank and the block No wear Nothing not even a blemish in the bore the count meter and log book read over 15 years at running at 2500 - 3500 RMP's.

it was a 2 bolt main 9.1 compression He just put new head gasket back in and all seal and new rings Just a full on stock Over haul kit the cam was like brand new it had wear but nothing like a motor that ran for over 250,000 milers or more

[72_gmc_suburban]

Originally Posted by stsalvage

But hardly any one uses it do to how expensive it is to buy here4 on the west coast

Without naming any names, the primary reason he converted to primary (based on what he told me) is that he had some "friendly" propane dealers that would sell him the propane without all the road taxes tacked onto it that they're supposed to charge. He said he could get a gallon of propane for $2 and change out the door, compared to the nearly $4 gasoline is out here.

Still, he had a lot of hacks on the body to make it all work and, combined with everything else, just didn't seem worth it for me to buy it.

[randamospenamos]

I have 460,000 on the original motor (never overhauled) of my 1985 gmc 2500 with a 350 that has always been run on propane. The problem with always running them on propane is that they won't want to run on gas anymore . That doesn't bother me though because I never have any problems with the propane system.
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Oh and as far as the cost of propane it is cheaper and there is no shortage of shady propane dealers I've been known to get mine for 50 cents a gallon.

[waybad]

you can run a higher compression with propane,, ( 104-110 octane)