Idle Cut-off Valve

Hello, ’67 Beetle community. We’ve been receiving a lot of emails about this topic. This is an older article from our good friend, Jay Salser. Give it a read if you have not already. As always, a huge thank you to Jay for all he does for 1967beetle.com.

If your Deluxe 1967 Beetle has a 30 Pict-1, VW 105-1 carburetor, you will have noticed, as in photograph #1, a little “canister” protruding from the passenger’s side, right at the generator. If you have not noticed this “canister” maybe yours has been replaced by a simple brass jet.

Volkswagen called this “canister” the Pilot Jet Valve. Today, it is called variously, although most people call it the Cut-off Valve or Idle Cut-off Valve.

Volkswagen carburetors have a brass jet which is called the Idle Jet. When the car is not in motion, for instance, the accelerator pedal is not being pushed. But we want the engine to continue to run so that when we are ready to start moving, the engine will be ready for that operation. The idle drilling draws gas, using vacuum, to keep the carburetor feeding some gasoline/air mixture to the engine—enough to keep it running at low rpms for us. The brass jet usually is marked g55 for many Beetle carburetors over the years.

The cars of yester-year sometimes had a tendency to “diesel”—that is, to continue running after the key was turned off. The Volkswagen was no different. Probably most of us have experienced this problem at one time or another. A VW mechanic tells me that dieseling could be due to a leaky gasket or a high fuel level or pressure. Such conditions would cause fuel to continue to feed through the idle port and cause the engine to run—usually very jerkily—ka-Chug-a–ka-Chug-a….

From September, 1964, Volkswagen issued a kit with a “Valve” (no name given for it although we know that popularly mechanics must have given this “Valve” a name). At Chassis 115-083-659 (Engine # 8 888 105), Volkswagen issued a complete installation kit containing the Valve (VW Part # 113-127-405) and relevant hoses, a bracket, a nipple and fasteners. You can understand how the kit fit the Fuel Pump-Carburetor scheme by viewing Photo #2. Installation was simple and quick.

I opine that the kit probably was retro-fitted onto cars when owners complained about dieseling.

Two kits were available so that the Valve could be retro-fitted to Fuel Pumps with the threaded inlet or installed on the later Fuel Pumps which had the tube inlet.

Gasoline passed through a straight-through tube which was soldered to the bottom of the Valve. The gasoline passed straight to the Fuel Pump inlet. The outlet tube of the Fuel Pump was connected to the near inlet on the top of the Valve by a looped, short piece of fuel hose. The far outlet tube of the Valve was connected to the Carburetor Fuel Bowl inlet tube by a longer length of braided hose. The pressure generated by the Fuel Pump was sufficient to keep gasoline passing through the Valve. However, as soon as the key was turned to the off position and the engine stopped and the Fuel Pump ceased pumping, gasoline flow immediately stopped—eliminating dieseling.

I consulted David Brown, a former Parts Manager for Volkswagen and a now-retired VW mechanic. He laughingly told me that he ignored dieseling on his VWs by turning off the key and, while leaving the car in gear and one foot on the brake, “snuffing the engine” by releasing the clutch. He said, “Of course Volkswagen wasn’t going to tell car owners to do that!” We had a little laugh together over that one!

For 1966 models, Volkswagen simplified the anti-dieseling remedy by combining the g55 Brass Idle Jet and an Electro-Magnetic fixture into one unit. Note the comparison of the Brass Jet and the Electro-Magnetic Valve in photo #3. This move eliminated the Valve at the Fuel Pump.

The Brass Jet of the Pilot Jet Valve is removable, revealing the Plunger of the Electro-Magnetic unit as illustrated in photo #4. Note that the Brass Idle Jet is identical to the removable Jet of the Pilot Jet Valve with the exception of the threaded portion which attaches it to the Electro-Magnetic portion of the Valve.

The Pilot Jet Valve (Idle Cut-off Valve) was connected to a pigtail on the wire which powered the Choke Heater. This was a very ingenious solution which removed possible leakage at the various hose connections of the former Valve at the Fuel Pump, as well as the weight hanging on the hose at that point. Knowing Volkswagen’s sense of economy, I can imagine that there was a cost savings, as well.

When the key was turned to the ON position, the Electro-Magnet snapped open the Valve’s Plunger and allowed gasoline to pass through the Idle Jet. Turn off the key and the Electro-Magnetic Valve released its Plunger and immediately cut gas to the idle drillings.

For 1966, this Electro-Magnetic Valve was, of course, 6 Volt.

For 1967 with the advent of the 12 Volt System, the Pilot Jet Valve was transformed into a 12 volt unit.

Some of you may find that you do not have the Idle Cut-off Electro-Magnetic Valve. Instead, you may have the g55 Brass Jet. This will work fine if all else is copacetic (i.e. no air or gas leaks, etc.). It will eliminate the pigtail wire to the Valve. And you likely will have no dieseling.

Acknowledgements:

• To my Favorite and Very Patient Photographer, Wife NevaTo David Brown, of Pennsylvania, who fields my constant barrage of questions.
• Ref: Bentley’s Workshop Manual, Volkswagen 1200, 1961-1965, Section K, K-2 page 12, Electro-Magnetic Pilot Jet Valve information; and Section K, K-3, page 2a, information concerning the Anti-Dieseling Valve Kit at the Fuel Pump.