Propane Conversion - 1977 Jeep Cherokee Chief - AMC 360
Here are photos of the propane installation on my 1977 Jeep Cherokee Chief. It has a AMC 360, T-18 4 spd, Dana 20, Dana 44's front and rear. This project was finished January 2006, and runs great. It started right up! There were a few things I learned from a guy who did a lot of conversions: 1) Advance the timing 10 degrees and remove the vacuum advance hose. 2) Run cooler spark plugs because propane runs hotter. 3) Propane is actually 101 octane, and will run like the devil if the engine is set up properly, but will show a 10% power loss on a regular gas motor without the timing advanced, the cooler plugs, and higher compression.
Here is the brand new IMPCO 425 Carb, sitting on an aftermarket 4bbl throttle plate. It is a 394 cfm ...next size up is a IMPCO 450 (500cfm) for a more performance engine. Since I drive mostly at high alitudes 3000-8000ft, I went with the leaner 425 (394cfm) carb. The 450 has a completely open top, instead of a capped air intake. This "carb" is known in the propane world as the "MIXER"
Here is the "VAPORIZER". It is an IMPCO Model "E" and is rebuilt. The small circular pod on the right, mounted on side of the larger pod is the auto shut off/on. The LIQUID propane line comes straight from the tank to this pod, (woven black line on the right) and it has a valve that senses engine vacuum (1/4" hose from the carb) When there is vacuum, it opens the valve and allows fuel to travel into the "vaporizer", when there is not, it shuts off.
The vaporizer is the larger of the two pods, and has some baffles inside that allow the LPG to expand and turn into a gas. There are water hoses running from the heating lines to this unit and back again to the heating, in order to keep it warm and contantly evaporating.
Here is the large 1" hose running from the vaporizer to the carb. The carb is a small square unit that sits on a holley throttle plate and linkage. You can buy the throttle plate new from SUMMIT for $89.
Here's the line running under the back deck where the spare tire should be. I ran it through the frame and AWAY from the shock mount to avoid any pinching or cutting in the case of a broken shock or mount. The high pressure line can be had for $80 from a company called "Oxnard Hose" in Oxnard, CA. They are nice guys. Whereever you get it, it should be capable of 300psi at least. Forklift supply places also have this hose.
This is the rear as the hose runs from the spare tire area, over the frame, and into the hole for the gasoline vent lines, and into the rear of the cab.