I became interested in alternative fuels when I was in university and like them even more now. I first converted a 78 New Yorker back in the late 1980s. When that car rusted out, I used the propane components to convert my current winter car (77 Pontiac). I still have that propane-440 and have plans to use it in another project.

Conversions are fairly straightforward and a straight (propane-only) conversion on a slant would be a lot like Tom Jennings' 1963 Rambler conversion. Open-loop Impco-style systems are the easiest and cheapest to do but can be the least fuel efficient. MegaSquirt-based injection systems are possible and have the potential for greater fuel economy and power. I expect to see more of them in the future.

A word of caution to anyone attempting a propane conversion: Please have your system inspected by a licensed automotive propane mechanic before you put any fuel into it.

Frank--

Thanks for the tips. I've looked at the Rambler site--it's a good model for the slant six conversion, I think. Are you using Impco? Do you use the feedback computer set up?

Joe

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Joe Hoppe

71 D100 225 Super Six 727 AT on 2008 Crown Vic CopCar frame

64 Valiant Wagon 225 904 AT 3:23 8.75"

I have the following on my car:

• Impco 425 mixer with a Quadrajet throttle body
• lean gas valve in the mixer
• Impco Model E converter
• Impco VFF30 Vacuum FueLock

I don't have a feedback ECU but I should. Due to the way my heater hoses run, my fuel economy drops off a bit in the winter due to reduced water flow to the converter. I'm trying to figure out the best way of using MegaSquirt (with a wideband O2 sensor) for control.

ughh i hate having to work on impco systems though easy as hell to install. Most systems i have to work on are for injected cars though. i've been playing around with the vapour injection systems from landi renzo which aren't to bad (for now) eliminates backfiring these systems and i think from what i've heard through the grapevine that Ford are developing a *liquid* injection system. With emissions laws out here now,most newer models from last year can now only have these vapour injection installed to them

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This should probably be on a new thread.

The Impco propane equipment works very well on older engines that were designed to use gasoline carburetors. Newer vehicles with intake manifolds designed to convey only air to the cylinders (ie port EFI) are prone to backfires when converted with Impco mixers. Backfires with Impco systems on older carbureted engines are due to poor maintenance or improperly configured ignition systems. The higher voltage requirement of LPG only reveals weaknesses in the ignition system.

Just as these "dry" EFI manifolds would work poorly if a carburetor were used in place of the throttle body, these manifolds don't work properly with propane mixers either. The backfiring problem occurs due to "Fuel Transport Delay." The only conversion that works properly on modern EFI engines (and meets very strict EPA requirements for alternative fuels) is port propane injection. The beauty of propane injection is that dual fuel systems don't require engine-specific adapters and all emission controls remain in place.