1973 - 1979 F-100 & Larger F-Series TrucksDiscuss the Dentsides Ford Truck
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Actually the vacuum source is internal to the carb. If you have a holley 4160 carb, there is a tube comming off the passenger side secondary barrel. That tube should have a line or tube going down to the exhaust manifold. That is the fresh air intake. There should be another tube that runs from the manifold up to the choke. The choke housing has a passage that connects to manifold vacuum. When running the vacuum pulls filtered, heated air from over the secondary, through the manifold to heat it and up to the choke housing.
Mine is a later model but on my 84, there is a tube made of flexible material that runs from the manifold on the passenger side to a valve in the air cleaner. The purpose of the tube is to bring warm air from the manifold to help with starting the vehicle under cold conditions. I have always called it a preheater hose but I don't know if this is the proper term. I found one at Advance Auto Parts back near the air filter, oil filter, PCV valve section of the store. Especially in the south, a lot of auto parts clerks have no idea of what the tube or hose is called nor what it is used for as it isn't all that necessary in our climate.
You can get these at most autoparts stores, and is carried in the HELP section.
You may have to order one though. Carbed vehicles are getting rarer...
Universal Choke tube kit, for hoking up the choke stove in the manifold to the carb. Motormite, Part number 76850.
Originally Posted by Centroplex
Mine is a later model but on my 84, there is a tube made of flexible material that runs from the manifold on the passenger side to a valve in the air cleaner. The purpose of the tube is to bring warm air from the manifold to help with starting the vehicle under cold conditions.
This is the Heat Riser system and is different to the Choke Stove system.
The Factory choke should already be Electric assist, but it needs both the choke tube and the power from the altenator stator to function properly.
Also without the choke tube attached, the carb will be sucking up unfiltered cold air, which can cause problems, and carb icing as well as cooling off the choke so it closes even with the engine hot.
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