I studied the operation of the Commander and understood what it would do, so I never did get the richer valve. Don't see any need for it. Yeah, I do run a lot of short trips ( 2-7 miles).

As for torching things, I do have stainless valves (int and exh) and hardened seats all around. I backed off the "rich" until the engine started to get lazy again and then just slightly tweaked richer. I don't have as much power, but now it runs what I consider "normal" in the low and mid range, instead of needing incredible amounts of advance to run.

Now I understand why some people claimed that propane destroyed their valves real fast. Someone set the carb for "max power"

I picked up the Commander from a surplus parts site online, it cost me $175 including all parts except the instructions!

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'81 W150 on Propane... Oversize valves, Oregon Camshaft cam, 10:5 static CR, Distributorless ignition, megajolt timing controller, PowerTrax lockers.

Speaking of all this... the engine cold starts very easily, but it's summer now. I don't prime it or anything, just crank and at about 4 to 6 seconds it fires and runs. I figure it takes that long for the engine vacuum to open the lockout and vapor to get to the carb (vapor hose is quite long - about 20 in). I can start and drive away in a few seconds after the oil pressure comes up and there's no hesitation or misfire or bog or anything.

That's "normal"?

I've seen lots of forklifts and stuff that stumble and stall and otherwise run badly when cold. Also, my tailpipe has a very slight dusting of "something" on it that's vaguely gray/tan in color. Normal?

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'81 W150 on Propane... Oversize valves, Oregon Camshaft cam, 10:5 static CR, Distributorless ignition, megajolt timing controller, PowerTrax lockers.

Is there anything you needed or wanted to know specifically, about how the MJ works or sets up?

I just found my kit is lacking (or has been lost) the fuel control valve. Any suggestions on what to use instead?

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'81 W150 on Propane... Oversize valves, Oregon Camshaft cam, 10:5 static CR, Distributorless ignition, megajolt timing controller, PowerTrax lockers.

I would definitely do headers- since you have a "dry" intake manifold, the exhaust is still transfering heat & raising the incoming air temps, making the eng more detonation prone.

A block-off plate between manifolds doesn't do much. My first MPFI /6 setup used the stock exh manifold with a block-off; it pinged like crazy & scorched the paint on the intake.

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63 Valiant Wagon
225 - 4 bbl

Yes, that's normal but you're thinking in terms of liquid fuels. The propane system is fail-safe in that fuel flow stops when the engine stops. First, the vacuum-lockoff (VFF-30) only allows fuel to flow when it senses mixer vacuum. Second, the converter supplies fuel at a negative pressure (ie, -1.5" WC) so that it only flows out of the mixer when there is venturi vacuum present. When the VFF-30 shuts off, there is still fuel present in the converter and it shouldn't dissipate in a properly functioning system.

When you shut a hot engine off, the propane vapor in the vapor line (hose that connects the converter to the mixer) is at around 185°F. As the fuel cools, the vapor contracts and its pressure decreases to a greater vacuum. When you try to start a cold engine, the converter must then build the pressure back up to -1.5" WC and this is why you have extra cranking time in the morning. Ideally, the vapor line should be as short as possible for this reason. It doesn't hurt to use cold start enrichment and there are 2 ways to do this. The first is the Start Assist Valve (PN SV), which is an electric valve that opens when the starter motor is engaged. The second is the Vacuum Power Valve (PN VPV), which is a vacuum-operated valve that opens with low manifold vacuum.
The only reason that an engine would stall would be if the liquid fuel is getting into the vapor line. Propane expands 270 times going from liquid to vapor so it doesn't take much to cause the fuel mixture to become over-rich. My guess is that those lift trucks are poorly maintained and the heat exchangers are not able to vaporize enough fuel with cold coolant.
There are no additives in LPG other the constituent gases (propane, propylene, ethane, butane, etc) and the odorant (ethyl mercaptan). My guess is that the dusting in your tailpipe is from the ash in the engine oil or the old deposits in the combustion chamber.
It would be great to see a write-up about this system for our Articles area. The beauty of the MJ ignition system is that dual ignition maps could be optimally set up for each fuel with a dual fuel system. This would be way better than the old dual curve ignition system.
The fuel control valve might be available as a separate item. See Commander Installation Instructions. I would also connect the atmospheric vent of the fuel control valve to the balance port on the mixer, especially if you're going to use the standard gas valve.

This was in my original plans, but so far, I have not been able to do this. First, the "real" headers are far too expensive, and second, I am highly concerned about durability, as this rig will see lots of rough road and some off road use.

I can't even afford Dutra's duals, really. I have looked at Mr Twister's power pipes, but have concerns about the thickness of the materials and eventual breaking due to stress transferred by the exhaust and rough roads.

Yes, the intake gets VERY hot while driving. The power increase when you drive into cool air (60 vs 90) is quite impressive. I'd like to plumb the air intake into in front of the radiator and put the air filter there. I'm concerned about durability, though, of gauze type filters while right behind the grille.

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'81 W150 on Propane... Oversize valves, Oregon Camshaft cam, 10:5 static CR, Distributorless ignition, megajolt timing controller, PowerTrax lockers.

I'll consider writing an article on the MJLJ after a bit. I'm not fully comfortable yet in thinking I know just how it works.

As for the stuff in the tailpipe, nothing appeared until I first ran it "rich". In fact, I think I had it quite rich, and perhaps it's a faint trace of soot from that.

I asked about the valve, because the Impco catalog lists it as "NSS", but then lists a "FCV-7" kit, which appears to be made of unobtainium. I know that many cars use vacuum modulating solenoids, I was just hoping someone knew of something cheap to use as a replacement.

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'81 W150 on Propane... Oversize valves, Oregon Camshaft cam, 10:5 static CR, Distributorless ignition, megajolt timing controller, PowerTrax lockers.

Just to put this into prospective I just bought my winter Propane. $2.09 a Gallon.
Frank

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Scrapple: Because a mind is a terrible thing to waste.
73 Duster - Race Car
66 Dart Wagon - DD
178" FED
82 D150
All Slant powered

I'll try to track down a replacement FCV for you.

Also, you can set up a propane system to take full advantage of ram air by connecting the balance port of the mixer to the vent port of the converter. This would also compensate for flow restrictions from a plugged up air filter.
Some places allow you to lock into a 1 year supply contract for motor fuel, which means means you buy the minimum volume quantity break (usually 1000 gallons) at a fixed price. You can lock-in your price in during the summer when the propane market is low.

I do this Every Year
Frank

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Scrapple: Because a mind is a terrible thing to waste.
73 Duster - Race Car
66 Dart Wagon - DD
178" FED
82 D150
All Slant powered

To follow-up on the fuel control valve, my installation manual lists PN AV1-15115-4 which is not available. However, the very similar AV1-15115-1 is available and can be used in place of the AV1-15115-4. AV1-15115-1 includes a bag of fittings, but if you have everything else, the included fittings will probably not be useful to you.

It would take about 1 week for me to order one in and probably about a week to get it out to you. Send me a PM if you want me to get it for you.

66aCUDA: $2.09/gallon is good price. On an energy basis, that costs the equivalent of $2.79/GGE.

I filled the tank a few days back at 1.99/gal.

So far, 300 miles and the gauge has moved from 3/4 (where it is when the bleeder spits liquid) to 1/2. I'm hoping for a target of 15 to 18 mpg normal driving. I think I have a decent chance of achieving it.

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'81 W150 on Propane... Oversize valves, Oregon Camshaft cam, 10:5 static CR, Distributorless ignition, megajolt timing controller, PowerTrax lockers.

What would be your guess as to base timing (mechanical) for 1700 and 2300 ?

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'81 W150 on Propane... Oversize valves, Oregon Camshaft cam, 10:5 static CR, Distributorless ignition, megajolt timing controller, PowerTrax lockers.

That depends upon what you're going to use as your all-in RPM. If you use 14° initial (@ 600 RPM) and 14° centrifugal, I calculate:

For 2500 RPM all-in: 22.1 @ 1700 & 26.5 @ 2300
For 2600 RPM all-in: 21.7 @ 1700 & 25.9 @ 2300
For 2700 RPM all-in: 21.3 @ 1700 & 25.3 @ 2300
For 2800 RPM all-in: 21.0 @ 1700 & 24.8 @ 2300
For 2900 RPM all-in: 20.7 @ 1700 & 24.3 @ 2300
For 3000 RPM all-in: 20.4 @ 1700 & 23.9 @ 2300

As for your fuel economy, I think regular gasoline is selling for about $3.73/gallon out your way today. If you get 15-18 mpg on propane, it's costing you as if you're getting about 28 to 33 mpg on gasoline. Not bad.

I finally was able to get my hands on another timing light and verified the precise timing settings again, in case I had some error. Anyway, I found the engine was STILL "lazy" and losing power on the top end without lots more advance, so I cranked the load setting a little more toward the rich and finally, it will go all the way to 3600 without falling on its face or needing a ton of advance ahead of where you and I predicted it would need to be.

It now feels responsive all through the rpm range, like it should.

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'81 W150 on Propane... Oversize valves, Oregon Camshaft cam, 10:5 static CR, Distributorless ignition, megajolt timing controller, PowerTrax lockers.