That's interesting, how / where did you mount the tank on the back of the van ?
It was a saddle tank of a big truck so it would not fit under my van. A new tank was darned expensive that was skinny and long to go under the van. I made frame rail extensions and put a permanent platform on the back 2' out. It also had trailer hitch and I pulled car trailer and camper with no issue. The bumper was also moved out.
I put the dual fuel set up on so you basically sat a propane carb on top of your carb. I had to raise the engine cover, dog house up to clear. So I had 35 gallons of propane and 21 gallons of gasoline. We drove to Montana several times non stop out and back to go hunting. The van would get 21 mpg on flat road. I built it in the race shop I worked in stock cam just TRW forged pistons and all TRW valve components. I think the coldest it was in was 30 deg. below zero. I pulled camper to Disney World with it and trailer across the U.S. several times. The 240 and 300 Ford 6 cylinders were bullet proof. Some of the local racers ran on circle track and kept up with V-8. You could cut Boss 351 heads apart and weld two together and spacing of cylinders were right so you had canted valve head. Drag racers did that. Ford also made SVO blocks for a while that were much stronger for drag racing. Use to have the fastest 1/4 mile for any inline 6 ever. It has 7 main bearings not 3 like the 144, 170, 200 and 250 Ford 6 cyl..
I stopped at an emissions check they had at a parts store one day and I had taken all the smog pump and air injectors off the 240 six in the van. It passed the current standards for the 1980's on propane so I switched over to gasoline and due to the inside of the engine being so clean it also passed on gasoline.
I seem to recall that propane was 105 octane. I also shaved the head 1/16" to up compression some. If it was cold weather you better shut it off running gasoline when real cold the propane will not vaporize enough to get the engine started. They do have heaters for that and mine did have one but used hot water from the engine so until warm it did not vaporize except when warm outside.
I had a 500 gallon tank at home and when on the road could usually find at truck stops. Your motor oil lasted much longer stayed clean. If I were going to get a new vehicle would be CNG for sure. In China all the taxis and city buses ran on CNG much cleaner. Of course any pics I ever had of the van are in a shoe box or on slides somewhere. I just crushed the van last year it got hit in the rear and ruined it. I drove it crashed until I bought SVO. The van had 467,000 miles on it. Ford dealer was going to send Ford pics when I hit 500,000 but got crashed.
Back in the 70's there was a plymouth or dodge 440 six pack drag car that ran on propane, called the Propane X I think. In years gone by when you passed a refinery and you saw the huge flame in the sky they were burning the waste gas from the refining process called propane, they could not store it as fast as they made it. They actually put the smell in it has no smell when pure.
I am drawing a blank on the brand but the carb is somewhere in the barn. Ordered it at the local gas supplier. You still had to pay road tax on the propane when they delivered it to my home. Was cheaper than gasoline for a while and of course they caught on and raised the price.
