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• Junk_head abstract "A junk head is a form of piston engine cylinder head, where the head is formed by a dummy piston mounted inside the top of the cylinder. In most other engine designs, the cylinder head is mounted on top of the cylinder block. That form has also been termed a "poultice head".It is obviously essential for any piston engine to seal the joint between block and head. This is usually done by means of a head gasket, a flat gasket on the surface of the block. In early engines, the high pressures and high temperatures made this a difficult trial for the materials of the day and gasket failures were common. The junk head requires no head gasket and is sealed by piston rings inside the cylinder bore, as for the power piston.An alternative solution was the monobloc engine, where the block and head were formed as one piece. This solved the sealing problem, but complicated manufacture and maintenance. Particularly when routine maintenance still required frequent head removal for de-coking, on a monobloc engine this required the removal of the pistons from the crankshaft end beneath. Cooling is difficult with a junk head, with either air or water. Water ports must be connected to the removable head and there is little space available within the cylinder diameter. If the engine uses the common form of overhead poppet valves, these would also be difficult to fit inside the limited space. Air cooling is also difficult, as the shape of the head is deeply re-entrant and it is difficult to arrange airflow to the deep well around the spark plug or injector. Bristol developed a two-part head to address this problem, with copper conducting fins.".
• Junk_head thumbnail Knight_sleeve-valve_engine,_sectioned_head,_inlet_stroke_(Autocar_Handbook,_Ninth_edition).jpg?width=300.
• Junk_head wikiPageID "25537172".
• Junk_head wikiPageRevisionID "483174563".
• Junk_head hasPhotoCollection Junk_head.
• Junk_head subject Category:Engine_technology.
• Junk_head subject Category:Sleeve_valve_engines.
• Junk_head type Artifact100021939.
• Junk_head type Device103183080.
• Junk_head type Engine103287733.
• Junk_head type Instrumentality103575240.
• Junk_head type Machine103699975.
• Junk_head type Motor103789946.
• Junk_head type Object100002684.
• Junk_head type PhysicalEntity100001930.
• Junk_head type SleeveValveEngines.
• Junk_head type Whole100003553.
• Junk_head comment "A junk head is a form of piston engine cylinder head, where the head is formed by a dummy piston mounted inside the top of the cylinder. In most other engine designs, the cylinder head is mounted on top of the cylinder block. That form has also been termed a "poultice head".It is obviously essential for any piston engine to seal the joint between block and head. This is usually done by means of a head gasket, a flat gasket on the surface of the block.".
• Junk_head label "Junk head".
• Junk_head sameAs m.09rskqy.
• Junk_head sameAs Q17098352.
• Junk_head sameAs Q17098352.
• Junk_head sameAs Junk_head.
• Junk_head wasDerivedFrom Junk_head?oldid=483174563.
• Junk_head depiction Knight_sleeve-valve_engine,_sectioned_head,_inlet_stroke_(Autocar_Handbook,_Ninth_edition).jpg.
• Junk_head isPrimaryTopicOf Junk_head.